Abstract
A phosphor is specified. The phosphor has the general molecular formula:
(MA).sub.a(MB).sub.b(MC).sub.c(MD).sub.d(TA).sub.e(TB).sub.f(TC).sub.g(TD).sub.h(TE).sub.i(TF).sub.j(XA).sub.k(XB).sub.l(XC).sub.m(XD).sub.n:E.
In this case, MA is selected from a group of monovalent metals, MB is selected from a group of divalent metals, MC is selected from a group of trivalent metals, MD is selected from a group of tetravalent metals, TA is selected from a group of monovalent metals, TB is selected from a group of divalent metals, TC is selected from a group of trivalent metals, TD is selected from a group of tetravalent metals, TE is selected from a group of pentavalent elements, TF is selected from a group of hexavalent elements, XA is selected from a group of elements which comprises halogens, XB is selected from a group of elements which comprises O, S and combinations thereof, -E=Eu, Ce, Yb and/or Mn, XC=N and XD=C. The following furthermore hold true: a+b+c+d=t; e+f+g+h+i+j=u; k+l+m+n=v; a+2b+3c+4d+e+2f+3g+4h+5i+6j−k−2l−3m−4n=w; 0.8≤t≤1; 3.5≤u≤4; 3.5≤v≤4; (−0.2)≤w≤0.2 and 0≤m<0.875 v and/or v≥1>0.125 v.
Claims
1. A phosphor having the general molecular formula
(MA).sub.1(TA).sub.3(TD).sub.1(XB).sub.4E, herein MA is selected from a group of monovalent metals which comprises Li, Na, K, Rb, Cs and combinations thereof, TA=Li, TD=Si, XB=O and E is selected from a group which comprises Eu, Ce, Yb, Mn and combinations thereof.
2. The phosphor as claimed in claim 1, wherein the phosphor has a crystal structure in which TA and TD are surrounded by XB and the resultant structural units are linked via common corners and edges to form a three-dimensional spatial network having cavities or channels and MA is arranged in the cavities or channels.
3. The phosphor as claimed in claim 1, wherein the phosphor has the following general molecular formula:
(Na.sub.rK.sub.1−r).sub.1(TA).sub.3(TD).sub.1(XB).sub.4:E, wherein 0≤r≤1.
4. The phosphor as claimed in claim 3, wherein the phosphor crystallizes in the space group I4.sub.1/a, I4/m or P-1.
5. The phosphor as claimed in claim 3, wherein 0.05<r≤0.2.
6. The phosphor as claimed in claim 3, wherein 0.4<r≤1.
7. The phosphor as claimed in claim 1, wherein the phosphor has the following general molecular formula: (Rb.sub.r′Li.sub.1−r′).sub.1(TA).sub.3(TD).sub.1(XB).sub.4:E, wherein 0≤r′≤1.
8. The phosphor as claimed in claim 7, wherein 0.25≤r′≤0.75.
9. The phosphor as claimed in claim 1, wherein the phosphor has the following general molecular formula: (K.sub.1−r″−r′″Na.sub.r″Li.sub.r′″).sub.1(TA).sub.3(TD).sub.1(XB).sub.4:E, wherein 0<r″<0.5 and 0<r′″<0.5.
10. The phosphor as claimed in claim 9, wherein the phosphor crystallizes in the space group I4/m or C2/m.
11. The phosphor as claimed in claim 1, wherein the phosphor has the following general molecular formula: (Rb.sub.r*Na.sub.1−r*).sub.1(TA).sub.3(TD).sub.1(XB).sub.4:E, wherein 0<r* <1.
12. The phosphor as claimed in claim 11, wherein the phosphor crystallizes in the space group I4/m or C2/m.
13. The phosphor as claimed in claim 1, wherein the phosphor has the following general molecular formula: (Cs,Na,K,Li).sub.1(TA).sub.3(TD).sub.1(XB).sub.4:E.
14. The phosphor as claimed in claim 1, wherein the phosphor has the following general molecular formula: (Cs,Na,Rb,Li).sub.1(TA).sub.3(TD).sub.1(XB).sub.4:E.
15. The phosphor as claimed in claim 1, wherein the phosphor has the following general molecular formula: (Cs,Na,K).sub.1(TA).sub.3(TD).sub.1(XB).sub.4:E.
16. The phosphor as claimed in claim 1, wherein the phosphor has the following general molecular formula: (Rb,Na,K).sub.1(TA).sub.3(TD).sub.1(XB).sub.4:E.
17. A method for producing a phosphor as claimed in claim 1 comprising the following method steps: A) mixing starting materials of the phosphor, B) heating the mixture obtained under A) to a temperature T1 of between 500 and 1400° C., C) annealing the mixture at a temperature T1 of 500 to 1400° C. for 0.5 minute to ten hours.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) In the drawings, like reference characters generally refer to the same parts throughout the different views. The drawings are not necessarily to scale, emphasis instead generally being placed upon illustrating the principles of the disclosed embodiments. In the following description, various embodiments described with reference to the following drawings, in which:
(2) FIGS. 1A, 1B, 1C, 1D, 1E, 1F show a selection of possible electroneutral molecular formulae of substitution experiments.
(3) FIGS. 2, 13, 23, 38, 63, 68, 74, 82, 83, 92, 93, 102, 103, 105, 112, 118B, 129, 131, 133, 135, 152B, 154, 161, 163 show emission spectra of exemplary embodiments of the phosphor according to the present disclosure.
(4) FIGS. 3, 14, 24, 39, 64, 84, 94, 104, 130, 132, 134, 136 show the Kubelka-Munk functions for exemplary embodiments of the phosphor according to the present disclosure.
(5) FIGS. 4, 43, 66, 70, 76, 86, 96, 121, 123 show a comparison of optical properties of an exemplary embodiment of the phosphor according to the present disclosure with comparative examples.
(6) FIGS. 5, 6, 44, 67, 69, 75, 85, 95, 122 show a comparison of emission spectra of an exemplary embodiment with comparative examples.
(7) FIG. 7 shows a comparison of the Kubelka-Munk function of an exemplary embodiment with comparative examples.
(8) FIGS. 8, 18, 25, 71, 77, 78, 88, 97, 107, 114, 137, 138, 139, 140, 160, 171, 172, 173 show excerpts from the crystal structure for exemplary embodiments of the phosphor according to the present disclosure.
(9) FIGS. 9, 19, 40, 65, 111, 118A, 177 show X-ray diffraction powder diffractograms using copper K.sub.α1 radiation or molybdenum K.sub.α1 radiation.
(10) FIGS. 10, 20, 26, 89, 98, 141, 142, 143, 144 show Rietveld refinements of X-ray powder diffractograms of exemplary embodiments of the phosphor according to the present disclosure.
(11) FIGS. 11, 12, 21, 22, 27, 28, 72, 73, 79, 80, 81, 90, 91, 99, 100, 108, 109, 110, 115, 116, 117, 126, 127, 128, 145-151, 152A, 158, 159, 174, 175, 176 show characteristic properties of exemplary embodiments of the phosphor according to the present disclosure.
(12) FIGS. 15, 16, 124 show comparisons of emission spectra of a conversion LED with an exemplary embodiment of the phosphor according to the present disclosure with comparative examples.
(13) FIGS. 17, 125, 164, 167 show a comparison of optical properties of a conversion LED with an exemplary embodiment of the phosphor according to the present disclosure with comparative examples.
(14) FIG. 29 shows a comparison of emission spectra of an exemplary embodiment with comparative examples and the sensitivity curve for melatonin production.
(15) FIG. 30 shows the overlap of emission spectra of various phosphors and various blue-emitting LEDs with the sensitivity curve for melatonin production.
(16) FIGS. 31, 120, 165 show color loci of various phosphors in the CIE standard diagram (1931).
(17) FIGS. 32, 33, 34 show comparisons of the color purity at different dominant wavelengths of the primary radiation of an exemplary embodiment with comparative examples.
(18) FIGS. 35, 36, 37, 166, 168 show simulated LED spectra at various excitation wavelengths.
(19) FIG. 41 shows the reflection positions and the relative intensity of the reflections of the X-ray diffraction powder diffractogram of an exemplary embodiment of the phosphor according to the present disclosure.
(20) FIGS. 42, 87, 101 show the thermal quenching behavior of an exemplary embodiment of the phosphor according to the present disclosure in comparison with the conventional phosphor.
(21) FIG. 45 shows the coverage of the color space rec2020 by different combinations of green and red phosphor.
(22) FIGS. 46 to 53 show graphical representations of the coverage of the color space rec2020 by different combinations of green and red phosphor.
(23) FIGS. 54A, 54B and 54C show the coverage of various standard color spaces and color loci of filtered spectra of different combinations of green and red phosphor.
(24) FIGS. 55 to 58 show the spanned color spaces of filtered spectra with different combinations of green and red phosphor upon excitation with a primary radiation λdom=448 nm.
(25) FIGS. 59 to 62 show the simulated emission spectra of conversion LEDs with different combinations of green and red phosphor.
(26) FIGS. 106, 113, 119, 153, 155, 162 show optical properties of exemplary embodiments.
(27) FIGS. 156 and 157 show the dependence of the peak wavelength on the cell volume of a unit cell.
(28) FIGS. 169 and 170 show spanned color spaces of the filtered overall radiation of various conversion LEDs.
DETAILED DESCRIPTION
(29) In the following description, numerous specific details are given to provide a thorough understanding of embodiments. The embodiments may be practiced without one or several specific details, or with other methods, components, materials, etc. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring aspects of the embodiments.
(30) Reference throughout this specification to “one embodiment” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, the appearances of the phrases “in one embodiment” or “in an embodiment” in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.
(31) FIGS. 1A, 1B, 1C, 1D, 1E and 1F show tables with possible electroneutral phosphors which are achievable by substitution experiments, analogously to the general molecular formula (MA).sub.a(MB).sub.b(MC).sub.c(MD).sub.d(TA).sub.e(TB).sub.f(TC).sub.g(TD).sub.h(TE).sub.i(TF).sub.j(XA).sub.k(XB).sub.l(XC).sub.m(XD).sub.n. The substitutions shown are merely by way of example, other substitutions are likewise possible. The activator E is illustrated in each case only in the general formula and not in the concrete embodiments, but is nevertheless also present in the concrete embodiments.
(32) FIG. 2 illustrates the emission spectrum of the first exemplary embodiment AB1 of the phosphor according to the present disclosure having the molecular formula NaLi.sub.3SiO.sub.4. The wavelength in nanometers is plotted on the x-axis and the emission intensity in percent is plotted on the y-axis. For measuring the emission spectrum, the phosphor according to the present disclosure was excited with primary radiation having a wavelength of 400 nm. The phosphor has a full width at half maximum of 32 nm or 1477 cm.sup.−1 and a dominant wavelength of 473 nm; the peak wavelength is approximately 469 nm.
(33) FIG. 3 shows a normalized Kubelka-Munk function (K/S), plotted against the wavelength λ in nm, for the first exemplary embodiment (AB1) of the phosphor according to the present disclosure. In this case, K/S was calculated as follows:
(34) K/S=(1−R.sub.inf).sup.2/2R.sub.inf, wherein R.sub.inf corresponds to the diffuse reflection of the phosphor.
(35) It is evident from FIG. 3 that the maximum of K/S for the first exemplary embodiment (AB1) of the phosphor according to the present disclosure is approximately 360 nm. High K/S values mean a high absorption in this range. The phosphor can be efficiently excited with a primary radiation starting from approximately 300 nm to 430 nm or 440 nm.
(36) FIG. 4 shows a comparison of the full width at half maximum (FWHM), the peak wavelength (λ.sub.peak), the dominant wavelength (λ.sub.dom) and the luminous efficiency (LER) between a first comparative example (VB1: BaMgAl.sub.10O.sub.17:Eu), a second comparative example (VB2: Sr.sub.5(PO.sub.4).sub.3Cl:Eu), a third comparative example (VB3: BaMgAl.sub.10O.sub.17:Eu) and the first exemplary embodiment of the phosphor according to the present disclosure NaLi.sub.3SiO.sub.4:Eu (AB1). VB1 and VB3 differ in the concentration of Eu. All phosphors emit radiation in the blue range of the electromagnetic spectrum. The peak wavelength of the phosphor according to the present disclosure NaLi.sub.3SiO.sub.4:Eu is of somewhat longer wavelength in comparison with the comparative examples. As evident, the phosphor according to the present disclosure NaLi.sub.3SiO.sub.4:Eu has a significantly smaller full width at half maximum and/or a higher luminous efficiency (LER) than the comparison examples. The shift in the peak wavelength to a longer wavelength and the smaller full width at half maximum result in an increase in the overlap with the eye sensitivity curve. Consequently, the phosphor according to the present disclosure has a very high luminous efficiency that is higher in comparison with the comparative examples.
(37) FIGS. 5 and 6 show the emission spectra of VB1, VB2, VB3 and AB1, as described in FIG. 4. In FIG. 5, the wavelength in nanometers is plotted on the x-axis and the emission intensity in percent is plotted on the y-axis. In FIG. 6, the wave number in cm.sup.−1 is plotted on the x-axis and the emission intensity in percent is plotted on the y-axis. The significantly smaller full width at half maximum of the phosphor according to the present disclosure NaLi.sub.3SiO.sub.4:Eu in comparison with VB1 and VB3 (BaMgAl.sub.10O.sub.17:Eu) becomes evident here. In contrast to AB1, moreover, BaMgAl.sub.10O.sub.17:Eu phosphors exhibit a low absorption starting from a wavelength of 350 nm (cf. FIG. 7). Together with the relatively large full width at half maximum, that results in a relatively poor color purity of the phosphors VB1 and VB3. Although the known phosphor VB2 exhibits a small full width at half maximum, it has the disadvantage that it contains chlorine. Many applications are subject to strict conditions as far as the chlorine content is concerned, and so the application of this phosphor is limited if only for this reason. The risk of the release of corrosive HCl during its production is also disadvantageous, which increases the costs for the synthesis equipment and the maintenance measures thereof.
(38) FIG. 7 shows a normalized Kubelka-Munk function (K/S), plotted against the wavelength λ in nm, for various phosphors VB1, VB2, VB3 and AB1, as defined in FIG. 4. The curve with the reference signs VB1, VB2 and VB3 represents K/S for known phosphors; the curve with the reference sign AB1 represents K/S for the first exemplary embodiment of the phosphor according to the present disclosure. It is evident that the phosphor according to the present disclosure AB1 has a higher absorption at longer wavelengths, in particular in the range starting from 360 nm, in comparison with the comparative examples VB1, VB2 and VB3. This is particularly advantageous since an efficient excitation of the phosphor according to the present disclosure with a primary radiation having a peak wavelength in the UV range to blue range of the electromagnetic spectrum, in particular in the range of between 300 nm and 460 nm, advantageously between 300 nm and 430 nm or 440 nm, is possible. Therefore, the phosphor according to the present disclosure is able to be employed particularly well in combination with semiconductor chips which have a primary radiation in the range of between 300 nm and 430 nm or 440 nm.
(39) FIG. 8 shows the tetragonal crystal structure of the phosphor NaLi.sub.3SiO.sub.4:Eu in a schematic illustration. The hatched circles represent the Na atoms. The crystal structure corresponds to the crystal structure of NaLi.sub.3SiO.sub.4, as described in B. Nowitzki, R. Hoppe, Neues über Oxide vom Typ A[(TO).sub.n]: NaLi.sub.3SiO.sub.4, NaLi.sub.3GeO.sub.4, NaLi.sub.3TiO.sub.4, [New findings concerning oxides of the type A[(TO).sub.n]: NaLi.sub.3SiO.sub.4, NaLi.sub.3GeO.sub.4, NaLi.sub.3TiO.sub.4] Revue de Chimie minérale, 1986, 23, 217-230. The crystal structure is isotypic with respect to that of CaLiAl.sub.3N.sub.4:Eu, described in P. Pust, A. S. Wochnik, E. Baumann, P. J. Schmidt, D. Wiechert, C. Scheu, W. Schnick, Ca[LiAl.sub.3N.sub.4]:Eu.sup.2+—A Narrow-Band Red-Emitting Nitridolithoaluminate, Chemistry of Materials 2014 26, 3544-3549.
(40) Two X-ray diffraction powder diffractograms using copper K.sub.α1 radiation are indicated in FIG. 9. The diffraction angles in ° 2θ values are indicated on the x-axis, and the intensity is indicated on the y-axis. The X-ray diffraction powder diffractogram provided with the reference sign I shows that of the first exemplary embodiment AB1 of the phosphor according to the present disclosure NaLi.sub.3SiO.sub.4:Eu. The X-ray diffraction powder diffractogram provided with the reference sign II shows the X-ray diffraction powder diffractogram for NaLi.sub.3SiO.sub.4 simulated from the crystal structure of NaLi.sub.3SiO.sub.4 (B. Nowitzki, R. Hoppe, Neues über Oxide vom Typ A[(TO).sub.n]: NaLi.sub.3SiO.sub.4, NaLi.sub.3GeO.sub.4, NaLi.sub.3TiO.sub.4, Revue de Chimie minérale, 1986, 23, 217-230). From the correspondence of the reflections it is evident that the phosphor according to the present disclosure NaLi.sub.3SiO.sub.4:Eu crystallizes in the same crystal structure as NaLi.sub.3SiO.sub.4.
(41) A crystallographic evaluation is found in FIG. 10. FIG. 10 shows a Rietveld refinement of the X-ray powder diffractogram of the first exemplary embodiment AB1, that is to say for NaLi.sub.3SiO.sub.4:Eu. For the Rietveld refinement, the atomic parameters for NaLi.sub.3SiO.sub.4 (table 7 in B. Nowitzki, R. Hoppe, Revue de Chimie minérale, 1986, 23, 217-230) were used to show that the crystal structure of NaLi.sub.3SiO.sub.4:Eu corresponds to that of NaLi.sub.3SiO.sub.4. The upper diagram here illustrates the superimposition of the measured reflections with the calculated reflections for NaLi.sub.3SiO.sub.4. The lower diagram illustrates the differences between the measured and calculated reflections.
(42) FIG. 11 shows crystallographic data of NaLi.sub.3SiO.sub.4.
(43) FIG. 12 shows atomic positions in the structure of NaLi.sub.3SiO.sub.4.
(44) FIG. 13 illustrates the emission spectrum of the second exemplary embodiment AB2 of the phosphor according to the present disclosure having the molecular formula KLi.sub.3SiO.sub.4:Eu.sup.2+. The wavelength in nanometers is plotted on the x-axis and the emission intensity in percent is plotted on the y-axis. For measuring the emission spectrum, the phosphor according to the present disclosure was excited with primary radiation having a wavelength of 400 nm. The phosphor exhibits a broadband emission from approximately 430 nm to approximately 780 nm and thus emits white radiation or the emitted radiation produces a white luminous impression. The color locus of the phosphor is advantageously near that of the Planckian radiator at 2700 K. The color locus is at the following coordinates CIE-x=0.449 and CIE-y=0.397 in the CIE standard chromaticity diagram from 1931. The color temperature (CCT) is 2742 K, the luminous efficiency is 290 lm/W, the CRI (color rendering index) is 81, and the color rendering index R9 is 21. A conversion LED comprising the phosphor according to the present disclosure KLi.sub.3SiO.sub.4:Eu.sup.2+ is thus suitable in particular for general lighting.
(45) FIG. 14 shows a normalized Kubelka-Munk function (K/S), plotted against the wavelength λ in nm, for the second exemplary embodiment (AB2) of the phosphor according to the present disclosure.
(46) It is evident from FIG. 14 that the maximum of K/S for the second exemplary embodiment (AB2) of the phosphor according to the present disclosure is approximately 340 nm. The phosphor can be efficiently excited with a primary radiation starting from approximately 300 nm to 430 nm or 440 nm.
(47) FIGS. 15 and 16 show simulated emission spectra of various conversion LEDs which emit white radiation. The primary radiation source used is an InGaN-based semiconductor layer sequence which emits a primary radiation having a peak wavelength of 410 nm (FIG. 15) or having a peak wavelength of 390 nm (FIG. 16). The construction of the conversion LEDs is shown in FIG. 17. As evident, the conversion LEDs according to the present disclosure (LED 1 and LED 2) using only one phosphor, the KLi.sub.3SiO.sub.4:Eu.sup.2+ according to the present disclosure, exhibit similar emission spectra to the comparative examples VLED2 and VLED1 each comprising a green and a red phosphor. The phosphor according to the present disclosure thus advantageously makes it possible to provide a conversion LED which emits warm-white light having a color temperature of less than 3500 K, advantageously less than 3000 K, and for this purpose requires only one phosphor, unlike known white-emitting conversion LEDs that require at least one green and one red phosphor in combination with a blue primary radiation.
(48) FIG. 17 compares various properties of conversion LEDs comprising the phosphor according to the present disclosure KLi.sub.3SiO.sub.4:Eu.sup.2+ (LED1, LED2) and the comparative examples (VLED1 and VLED2). In this case, λ.sub.prim stands for the wavelength of the primary radiation. The first and second phosphors are indicated in the third and fourth columns. CIE-x and CIE-y indicate the color coordinates x and y of the radiation in the CIE standard chromaticity diagram from 1931. CCT/K indicates the correlated color temperature of the overall radiation in kelvins. R9 stands for a color rendering index known to the person skilled in the art (saturated red). LER stands for the luminous efficiency (“luminous efficacy”) in lumens per watt. As evident, the conversion LEDs comprising the phosphor according to the present disclosure KLi.sub.3SiO.sub.4:Eu.sup.2+ as sole phosphor have similar optical properties to conventional conversion LEDs based on two phosphors. In this case, however, the disadvantages arising from the use of two or more phosphors are eliminated. Firstly, the resulting spectrum is greatly dependent on the used ratio of the phosphors. As a result of batch fluctuations in phosphor production, frequent adaptations of the concentration of the phosphors are necessary as a result, which makes the production of the conversion LEDs very complicated. The phosphors additionally exhibit different emission properties depending on temperature, the radiance of the primary radiation and the excitation wavelength and additionally exhibit a different degradation behavior, that is to say a different stability with regard to temperature, radiation, moisture or gas influences. The production of phosphor mixtures may also be difficult if the phosphors differ greatly in their physical properties such as, for example, density, grain size and in the sedimentation behavior. With the use of two phosphors, all these effects lead to fluctuating color locus distributions and color shifts under changing operating conditions, for example current and/or temperature, in the products. In order conventionally to obtain a high color rendering index, advantageously with low color temperature, in particular less than 3500 K or less than 3000 K, red-emitting phosphors are required. However, all known red-emitting phosphors can only be synthesized by means of complex production methods and are therefore very much more expensive than known green and yellow phosphors. By contrast, the phosphor according to the present disclosure KLi.sub.3SiO.sub.4:Eu.sup.2+ can be produced cost-effectively since the starting materials are commercially available, stable and moreover very inexpensive. Moreover, the synthesis does not require an inert gas atmosphere and therefore proves to be comparatively simple.
(49) The use of the phosphor according to the present disclosure in a white-emitting conversion LED has numerous advantages. It is possible to use a primary radiation which is not perceived or is only scarcely perceived by the human eye (300 nm to 430 nm or 440 nm). Fluctuations of the primary radiations thus do not adversely affect the overall radiation properties. No color adaptation is required since the emission spectrum is constant. The conversion LEDs can be produced with a high throughput since color adaptation or complex chip binning is not required. No color shifts or other negative effects on the emission spectrum as a result of selective degradation of only one phosphor or changes in the primary radiation caused by temperature or forward current fluctuations occur. Furthermore, the conversion LED does not have an inherent color, but rather exhibits a white appearance in the switched-off state. Therefore, the phosphor is also suitable for “remote phosphor” arrangements in which a yellow or orange appearance in the switched-off state is not desired. A partial conversion of the primary radiation can also be carried out depending on the application. Since it is possible to excite the phosphor with a primary radiation in the range of 300 nm to 430 nm or 440 nm, a contribution of the primary radiation, advantageously in the short-wave blue range of the electromagnetic spectrum, to the overall radiation has the effect that objects illuminated thereby appear whiter, more radiant and therefore more attractive. By way of example, optical brightening agents in textiles can be excited thereby.
(50) FIG. 18 shows a triclinic crystal structure of the phosphor KLi.sub.3SiO.sub.4:Eu in a schematic illustration. The hatched circles represent the K atoms. The crystal structure corresponds to the crystal structure of KLi.sub.3SiO.sub.4, as described in K. Werthmann, R. Hoppe, Über Oxide des neuen Formeltyps A[(T.sub.4O.sub.4)]: Zur Kenntnis von KLi.sub.3GeO.sub.4, KLi.sub.3SiO.sub.4 und KLi.sub.3TiO.sub.4 [Regarding oxides of the new formula type A[(T.sub.4O.sub.4)]: Zur Kenntnis von KLi.sub.3GeO.sub.4, KLi.sub.3SiO.sub.4 and KLi.sub.3TiO.sub.4], Z. Anorg. Allg. Chem., 1984, 509, 7-22. The crystal structure is isotypic with respect to that of SrLiAl.sub.3N.sub.4:Eu, described in P. Pust, V. Weiler, C. Hecht, A. Tücks, A. S. Wochnik, A.-K. Henß, D. Wiechert, C. Scheu, P. J. Schmidt, W. Schnick, Narrow-Band Red-Emitting Sr[LiAl.sub.3N.sub.4]:Eu.sup.2+ as a Next-Generation LED-Phosphor Material Nat. Mater. 2014 13, 891-896.
(51) Two X-ray diffraction powder diffractograms using copper K.sub.α1 radiation are indicated in FIG. 19. The diffraction angles in ° 2θ values are indicated on the x-axis and the intensity is indicated on the y-axis. The X-ray diffraction powder diffractogram provided with the reference sign III shows that of the second exemplary embodiment of the phosphor according to the present disclosure KLi.sub.3SiO.sub.4:Eu. The X-ray diffraction powder diffractogram provided with the reference sign IV shows the X-ray diffraction powder diffractogram for KLi.sub.3SiO.sub.4 simulated from the crystal structure of KLi.sub.3SiO.sub.4. From the correspondence of the reflections it is evident that the phosphor according to the present disclosure KLi.sub.3SiO.sub.4:Eu crystallizes in the same crystal structure as KLi.sub.3SiO.sub.4.
(52) A crystallographic evaluation is found in FIG. 20. FIG. 20 shows a Rietveld refinement of the X-ray powder diffractogram of the second exemplary embodiment AB2, that is to say KLi.sub.3SiO.sub.4:Eu. For the Rietveld refinement, the atomic parameters for KLi.sub.3SiO.sub.4 (K. Werthmann, R. Hoppe, Uber Oxide des neuen Formeltyps A[(T4O4)]: Zur Kenntnis von KLi3GeO4, KLi.sub.3SiO.sub.4 und KLi3TiO4, Z. Anorg. Allg. Chem., 1984, 509, 7-22) are used to show that the crystal structure of KLi.sub.3SiO.sub.4:Eu corresponds to that of KLi.sub.3SiO.sub.4. In this case, the upper diagram illustrates the superimposition of the measured reflections with the calculated reflections for KLi.sub.3SiO.sub.4. The lower diagram illustrates the differences between the measured and calculated reflections. A peak of an unknown secondary phase has been marked with an asterisk.
(53) FIG. 21 shows crystallographic data of KLi.sub.3SiO.sub.4.
(54) FIG. 22 shows atomic positions in the structure of KLi.sub.3SiO.sub.4.
(55) FIG. 23 illustrates the emission spectrum of the third exemplary embodiment AB3 of the phosphor according to the present disclosure having the molecular formula (Na.sub.0.5K.sub.0.5)Li.sub.3SiO.sub.4:Eu.sup.2+. The wavelength in nanometers is plotted on the x-axis and the emission intensity in percent is plotted on the y-axis. For measuring the emission spectrum, the phosphor according to the present disclosure was excited with primary radiation having a wavelength of 400 nm. The phosphor has a full width at half maximum of less than 20 nm and a peak wavelength of 486 nm. With this small full width at half maximum, this phosphor belongs to the most narrowband Eu.sup.2+-doped phosphors known. The peak wavelength is in the blue-green spectral range of the electromagnetic spectrum, which spectral range can also be referred to as cyan-colored. Only a small number of phosphors having a peak wavelength in this range have been known hitherto and none of these phosphors has such a small full width at half maximum. With a peak wavelength of 486 nm and the small full width at half maximum, the phosphor has a good overlap with the eye sensitivity curve. The conversion of the UV or blue primary radiation into a secondary radiation having a somewhat longer wavelength in the blue range of the electromagnetic spectrum (peak wavelength of 486 nm), increases the efficiency of the conversion LED. The peak wavelength of the secondary radiation is closer to the eye sensitivity maximum at 555 nm in comparison with the primary radiation, whereby the emitted radiation has a higher overlap with the eye sensitivity curve and is thus perceived as brighter. Similar optical properties are also obtained with AB9, AB14, AB15 and AB16.
(56) FIG. 24 shows a normalized Kubelka-Munk function (K/S), plotted against the wavelength λ in nm, for the third exemplary embodiment (AB3) of the phosphor according to the present disclosure.
(57) It is evident from FIG. 24 that the maximum of K/S for the third exemplary embodiment (AB3) of the phosphor according to the present disclosure is between 350 nm and 420 nm. Up to 500 nm, K/S is significantly above the value zero. The phosphor (Na.sub.0.5K.sub.0.5)Li.sub.3SiO.sub.4:Eu.sup.2+ can be efficiently excited with a primary radiation starting from approximately 340 nm.
(58) FIG. 25 shows the tetragonal crystal structure of the phosphor (Na.sub.0.5K.sub.0.5)Li.sub.3SiO.sub.4:Eu.sup.2+ in a schematic illustration. The hatched circles represent the Na atoms; the circles enclosing white areas represent the K atoms. The crystal structure was determined from X-ray powder diffractogram data. The crystal structure of CsKNa.sub.2Li.sub.12Si.sub.4O.sub.16 with Cs being substituted by K was used as the starting point.
(59) A crystallographic evaluation is found in FIG. 26. FIG. 26 shows a Rietveld refinement of the X-ray powder diffractogram of the third exemplary embodiment AB3, that is to say (Na.sub.0.5K.sub.0.5)Li.sub.3SiO.sub.4:Eu.sup.2+. The parameters and atomic coordinates of all non-Li atoms were freely refined. In this case, the upper diagram illustrates the superimposition of the measured reflections with the calculated reflections for CsKNa.sub.2Li.sub.12Si.sub.4O.sub.16. The lower diagram illustrates the differences between the measured and calculated reflections. The phosphor (Na.sub.0.5K.sub.0.5)Li.sub.3SiO.sub.4:Eu.sup.2+ is structurally isotypic with respect to the compounds CsKNa.sub.2Li.sub.8{Li[SiO.sub.4]}.sub.4, RbNa.sub.3Li.sub.8{Li[SiO.sub.4]}.sub.4, CsNa.sub.3Li.sub.8{Li[GeO.sub.4]}.sub.4 and RbNa.sub.3Li.sub.8{Li[TiO.sub.4]}.sub.4. The structure is also similar to that of the first exemplary embodiment NaLi.sub.3SiO.sub.4:Eu and the second exemplary embodiment KLi.sub.3SiO.sub.4:Eu of the phosphor according to the present disclosure, but has a complicated arrangement of the alkali metals.
(60) FIG. 27 shows crystallographic data of (Na.sub.0.5K.sub.0.5)Li.sub.3SiO.sub.4.
(61) FIG. 28 shows atomic positions in the structure of (Na.sub.0.5K.sub.0.5)Li.sub.3SiO.sub.4.
(62) FIG. 29 shows the emission spectra of the third exemplary embodiment of the phosphor according to the present disclosure AB3 and three comparative examples ClS, OS and G, wherein ClS stands for Ca.sub.8Mg(SiO.sub.4).sub.4Cl.sub.2:Eu, OS stands for (Sr,Ba).sub.2SiO.sub.4:Eu and G stands for Lu.sub.3(Al,Ga).sub.5O.sub.12:Ce. All the phosphors emit in the blue to blue-green range of the electromagnetic spectrum. AB3, as evident, has the smallest full width at half maximum and the peak wavelength is shifted to shorter wavelengths in comparison with the comparative examples. Therefore, the phosphor according to the present disclosure is suitable for example for an application in signal lights such as blue lights of, for example, police vehicles, ambulances, emergency doctor vehicles or fire department vehicles, the dominant wavelength of which is advantageously in a range of between 465 nm and 480 nm. The use of the comparative examples is less well suited thereto since the peak wavelengths thereof are above 510 nm, whereas the phosphor according to the present disclosure has a peak wavelength of 486 nm. On account of similar optical properties, AB9, AB14, AB15 and AB16 are also suitable for an application in signal lights.
(63) The curve designated by smel shows the sensitivity curve for melatonin production, that is to say with what wavelengths melatonin production in the body can best be suppressed (“human response function for melanopic effects”; Lucas et al., Trends in Neurosciences January 2014 Vol. 37 No. 1). As evident, the emission spectrum of AB3 exhibits a high overlap with smel, and so this radiation can be effectively used for suppressing the formation of melatonin. Such irradiation can lead to an increased vigilance or ability to concentrate.
(64) FIG. 30 shows the overlap of emission spectra of various phosphors (AB3, CIS, OS and G, as described under FIG. 29) and various blue-emitting LEDs (unconverted) with the sensitivity curve for melatonin production. The LEDs are light-emitting diodes having InGaN-based semiconductor chips. The LEDs Ipeak430 nm (peak wavelength of 430 nm) and Ipeak435 nm (peak wavelength of 435 nm) are not usually commercially available in large numbers, but are very efficient. The LEDs Ipeak440 nm (peak wavelength of 440 nm), Ipeak445 nm (peak wavelength of 445 nm), Ipeak450 nm (peak wavelength of 450 nm) and Ipeak455 nm (peak wavelength of 455 nm) are commercially available, inexpensive and efficient. The LEDs Ipeak460 nm (peak wavelength of 460 nm), Ipeak465 nm (peak wavelength of 465 nm) and Ipeak470 nm (peak wavelength of 470 nm) have only low efficiency and are not usually commercially available. InGaN-based semiconductor chips can in principle emit a radiation having a peak wavelength of up to 500 nm, although the efficiency decreases as the wavelength increases, for which reason they are produced in large numbers usually only up to a peak wavelength of up to approximately 460 nm. As a result, the areas of application for InGaN-based semiconductor chips in light-emitting diodes (without phosphor) are limited. As evident, the emission of the phosphor according to the present disclosure AB3 exhibits a greater overlap with the sensitivity curve for melatonin production than the phosphors ClS, OS and G and also than the InGaN-based LEDs. Melatonin production can thus be efficiently suppressed with the phosphor according to the present disclosure. On account of similar optical properties, AB9, AB14, AB15 and AB16 are also suitable for suppressing melatonin production.
(65) FIG. 31 shows the CIE standard diagram (1931), wherein the CIE-x portion of the primary color red is plotted on the x-axis and the CIE-y portion of the primary color green is plotted on the y-axis. The color loci of various phosphors (AB3, ClS, OS and G, as described under FIG. 29) are depicted in the CIE standard diagram. The black quadrilaterals represent color loci of various blue and blue-green InGaN semiconductor chips having peak wavelengths of between 430 nm and 492 nm and dominant wavelengths of between 436 nm and 493 nm. The black dot marks the white point Ew having the coordinates CIE-x=1/3 and CIE-y=1/3. The black lines linking the color loci of a blue indium gallium nitride semiconductor chip (λpeak=445 nm; λ.sub.dom=449 nm) with the color loci of the phosphors represent the conversion lines of conversion LEDs that are constructed from the indium gallium nitride semiconductor chip and corresponding phosphors. The area identified by EVL shows the typical blue color space for products for application in the field of signal lights for police vehicles, for example. The open circles mark color loci having 100% color purity for selected dominant wavelengths at 468 nm, 476 nm and 487 nm. The dashed line represents color loci having dominant wavelengths at 487 nm with varying color purity. Color loci on this dashed line which lie nearer to the open circle 487 exhibit higher color purities than color loci that lie nearer to the white point E. The advantageous effects of the new phosphor AB3 become clear from this figure: the conversion line (KL) of a typical blue LED to the color locus of the phosphor according to the present disclosure AB3 intersects the EVL color space in the center, whereas the conversion lines of the same blue LED comprising the phosphors OS, ClS and G exhibit only a small overlap with the EVL color space. It is thus advantageously possible to obtain a plurality of color spaces within the EVL color space by using the phosphor AB3 by comparison with the conventional phosphors. Moreover, the conversion line K intersects the dashed line for the dominant wavelength 487 nm at the point I1, which has a higher color purity in comparison with the intersection points of the conversion lines of the known phosphors. The same improvement in the color purity using the phosphor according to the present disclosure AB3 is also manifested for other target dominant wavelengths, in particular within the EVL color space. The corresponding lines are not shown, for the sake of clarity. A high color purity results in a more saturated color impression. The phosphor according to the present disclosure thus makes it possible to obtain additional color loci which have not been able to be achieved hitherto. The phosphor according to the present disclosure (Na.sub.0.5K.sub.0.5)Li.sub.3SiO.sub.4:Eu.sup.2+ is therefore particularly suitable for conversion LEDs which emit a blue radiation with high color saturation. These conversion LEDs are suitable for use in blue lights or else for “color on demand” applications. On account of similar optical properties, AB9, AB14, AB15 and AB16 are also suitable for conversion LEDs which emit a blue radiation with high color saturation.
(66) FIGS. 32, 33 and 34 show a comparison of the achievable color purities of different conversion LEDs at various target dominant wavelengths and wavelengths of the primary radiation. In order to carry out the simulation experiments, a blue semiconductor chip was combined with the different phosphors AB3, ClS, OS and G. Semiconductor chips based on InGaN and having a high efficiency were used in this case. The content of phosphor was varied for each experiment in order to attain the target dominant wavelength; the color purity was subsequently determined from the resulting spectra. The results show that for all chosen target dominant wavelengths and all chosen wavelengths of the primary radiation, the conversion LEDs comprising the phosphor AB3 and also comprising AB9, AB14, AB15 and AB16 (not shown) exhibit a significantly higher color purity than the comparative examples.
(67) FIGS. 35, 36 and 37 shows the simulated emission spectra of the conversion LEDs corresponding to FIGS. 32, 33 and 34. In this case, FIG. 35 shows the emission spectra of a conversion LED having a primary radiation of 430 nm and of a conversion LED having a primary radiation of 455 nm in each case comprising the phosphor AB3 at a target dominant wavelength of 468 nm. FIG. 36 shows the emission spectra of a conversion LED having a primary radiation of 430 nm and of a conversion LED having a primary radiation of 455 nm in each case comprising the phosphor AB3 at a target dominant wavelength of 487 nm. FIG. 37 shows the emission spectra of a conversion LED having a primary radiation of 430 nm and of a conversion LED having a primary radiation of 455 nm in each case comprising the phosphor AB3 at a target dominant wavelength of 476 nm.
(68) FIG. 38 illustrates the emission spectrum of the fourth exemplary embodiment AB4 of the phosphor according to the present disclosure having the molecular formula (Na.sub.0.25K.sub.0.75)Li.sub.3SiO.sub.4:Eu.sup.2+. The wavelength in nm is plotted on the x-axis and the emission intensity in % is plotted on the y-axis. For measuring the emission spectrum, the phosphor according to the present disclosure was excited with a primary radiation having a wavelength of 400 nm. The phosphor has a full width at half maximum of less than 50 nm, a peak wavelength of 529 nm, a dominant wavelength of 541 nm and a color locus in the CIE color space having the coordinates CIE-x: 0.255 and CIE-y: 0.680. The narrow full width at half maximum of the phosphor leads to a saturated green emission of the phosphor.
(69) FIG. 39 shows a normalized Kubelka-Munk function (K/S), plotted against the wavelength λ in nm, for the fourth exemplary embodiment (AB4) of the phosphor according to the present disclosure. The phosphor according to the present disclosure can be efficiently excited with a primary radiation in the range of between 330 nm and 500 nm, advantageously 340 nm to 460 nm, particularly advantageously 350 nm to 450 nm. As a result, the phosphor is suitable in particular for backlighting applications, using a semiconductor chip with a primary radiation in the near UV range or blue range of the electromagnetic spectrum.
(70) FIG. 40 shows the X-ray powder diffractogram of the fourth exemplary embodiment AB4. The intensity is indicated on the y-axis and the ° 2θ values are indicated on the x-axis. The reflection positions and the relative intensity in % of the reflection positions of the X-ray powder diffractogram are indicated in FIG. 41.
(71) In FIG. 42, the emission intensity in % is plotted against the temperature in ° C. As evident, the exemplary embodiment AB4 of the phosphor according to the present disclosure exhibits a high thermal stability. FIG. 42 shows the thermal quenching behavior of the phosphor according to the present disclosure AB4 in comparison with a conventional phosphor OS2, a green orthosilicate of the formula (Sr,Ba).sub.2SiO.sub.4:Eu. The phosphors were excited with a blue primary radiation having a wavelength of 460 nm at various temperatures from 25 to 225° C. and their emission intensity was recorded in the process. It is clearly evident that the phosphor AB4 according to the present disclosure has a significantly smaller loss of emission intensity at typical temperatures that prevail in a conversion LED, in particular temperatures above 140° C. The phosphor can thus advantageously be used even at higher operating temperatures in conversion LEDs.
(72) FIG. 43 shows various optical properties of the fourth exemplary embodiment of the phosphor according to the present disclosure AB4 in comparison with conventional phosphors G2 and OS2. In this case, OS2 stands for a phosphor of the formula (Sr,Ba).sub.2SiO.sub.4:Eu and G2 stands for a phosphor of the formula Lu.sub.3(Al,Ga).sub.5O.sub.12:Ce. All three phosphors exhibit a similar dominant wavelength. In this case, however, the phosphor AB4 according to the present disclosure exhibits a significantly higher luminous efficiency (LER) and a significantly higher color purity. This leads to an improved color saturation, as a result of which it is possible to achieve a higher color space coverage, and to an improved overall efficiency. The reason for the improved properties is the small full width at half maximum of the fourth exemplary embodiment AB4 having the formula (Na.sub.0.25K.sub.0.75)Li.sub.3SiO.sub.4:Eu.sup.2+ of the phosphor according to the present disclosure in comparison with the conventional phosphors. On account of a similar position of the peak wavelengths and values of the full width at half maximum, the exemplary embodiments AB5, AB7, AB13 and AB8 likewise exhibit improved properties. The high luminous efficiency increases the efficiency of green conversion LEDs having partial or full conversion in comparison with green conversion LEDs comprising known green phosphors having a comparable dominant and/or peak wavelength.
(73) FIG. 44 shows a comparison of the emission spectra of the fourth exemplary embodiment AB4 of the phosphor according to the present disclosure in comparison with the conventional phosphors G2 and OS2 described under FIG. 43.
(74) FIG. 45 shows the coverage of the color space rec2020 (xy) in the CIE color space system and rec2020 (u′v′) in the CIE LUV color space system (1976) by different combinations of a green phosphor and a red phosphor in conjunction with a blue primary radiation of varying dominant wavelength. In this case AB4 stands for the fourth exemplary embodiment (Na.sub.0.25K.sub.0.75)Li.sub.3SiO.sub.4:Eu.sup.2+ of the phosphor according to the present disclosure and AB5 stands for the fifth exemplary embodiment (Rb.sub.0.5Li.sub.0.5)Li.sub.3SiO.sub.4 of the phosphor according to the present disclosure, and BS stands for a conventional green-emitting beta-SiAlON:Eu phosphor. The proportions of blue, green and red radiation were adapted such that the white color locus for typical backlighting applications (CIE-x=0.278 and CIE-y=0.255) was obtained. Typical color filter curves were applied to the resulting spectrum and the resulting color loci for blue, green and red were calculated. The overlap of the resulting color space with the standard color spaces was then calculated and compared. In all cases it is evident that the spectra obtained with the exemplary embodiments AB4 and AB5 of the phosphor according to the present disclosure result in a greater coverage of the respective color space. Like AB4 and AB5, AB7, AB13 and AB8 also have a high coverage of the respective color space on account of the similar peak wavelength and full width at half maximum (FIGS. 76, 129, 86) in combination with the red phosphors indicated in FIG. 45. A greater bandwidth of colors can thus be rendered with the phosphors according to the present disclosure. Thus, by way of example, a display device, such as a display, having a conversion LED comprising the phosphor according to the present disclosure can render a significantly increased number of colors by comparison with what has been possible hitherto with conventional phosphors.
(75) FIGS. 46 to 53 show a graphical representation of the results of the color space coverage as described in FIG. 45 for a dominant wavelength of the primary radiation at 448 nm. The second red phosphor used, together with its molecular formula, is indicated in each of the diagrams.
(76) FIGS. 54A, 54B and 54C show a more comprehensive list of the data from FIG. 45, which additionally show the color loci of the filtered spectra and coverages with other standard color spaces.
(77) FIGS. 55 to 58 show the spanned color spaces of various examples of the combinations illustrated in FIG. 45 with a wavelength of the primary radiation λ.sub.dom=448 nm. Each figure shows a comparison of three different green phosphors (AB4, AB5 or BS) in each case combined with a red phosphor, which is indicated with its molecular formula in the figures. The color spaces spanned by the filtered spectra with the exemplary embodiments according to the present disclosure AB4 and AB5 are almost congruent. It is evident that a greater bandwidth of colors can be rendered with the exemplary embodiments AB4 and AB5 of the phosphor according to the present disclosure, primarily in the green and red corners of the spanned color triangle (marked by arrows). A similar behavior is also obtained with the exemplary embodiments AB7, AB13 and AB8 (not illustrated). This is assigned to the very narrowband emission of the phosphors according to the present disclosure AB4 and AB5, AB7, AB13 and AB8. The bandwidth of green colors is thus increased by the use of the phosphors according to the present disclosure AB4, AB5, AB7, AB13 and AB8 in comparison with conventional phosphors. The narrow full width at half maximum of the phosphors according to the present disclosure additionally reduces the radiation loss that arises as a result of the filtering. In comparison with the known phosphor β-SiAlON (BS), the phosphors according to the present disclosure can be produced on the basis of inexpensive starting materials and moreover the synthesis is carried out at moderate temperatures. This keeps the production costs low, which makes the phosphors also economically highly attractive for the production of mass-produced products such as LCD televisions, computer monitors or displays for smartphones or tablets.
(78) FIGS. 59 to 62 show the corresponding conversion LED spectra of the examples of FIGS. 55 to 58. The red phosphor is indicated together with its molecular formula in the figures.
(79) FIG. 63 illustrates the emission spectrum of the fifth exemplary embodiment AB5 of the phosphor according to the present disclosure having the molecular formula (Rb.sub.0.5Li.sub.0.5)Li.sub.3SiO.sub.4. The wavelength in nm is plotted on the x-axis and the emission intensity in % is plotted on the y-axis. For measuring the emission spectrum, the phosphor according to the present disclosure was excited with light having a wavelength of 400 nm. The phosphor has a full width at half maximum of 43 nm and a peak wavelength of 528 mm and a dominant wavelength of 539 nm. The coordinates CIE-x and CIE-y are at 0.238 and 0.694. The phosphor thus proves to be very suitable for backlighting applications that have to have a saturated green hue.
(80) FIG. 64 shows a standardized Kubelka-Munk function (K/S), plotted against the wavelength λ in nm, for the fifth exemplary embodiment of the phosphor according to the present disclosure. The maximum of K/S for the fifth exemplary embodiment of the phosphor according to the present disclosure is approximately 400 nm, although the range of high absorption extends into the blue-green spectral range up to approximately 500 nm. Therefore, the phosphor can be efficiently excited with a primary radiation having a wavelength of between 330 and 500 nm, advantageously 340 and 460 nm, particularly advantageously 350 to 450 nm.
(81) FIG. 65 shows the X-ray powder diffractogram of the fifth exemplary embodiment AB5 of the phosphor according to the present disclosure with the reference sign V. The X-ray powder diffractogram provided with the reference sign VI shows a simulated diffractogram of the compound RbLi(Li.sub.3SiO.sub.4).sub.2(K. Bernet, R. Hoppe, Ein “Lithosilicat” mit Kolumnareinheiten: RbLi.sub.5{Li[SiO.sub.4]}.sub.2 [A “lithosilicate” having columnar units: RbLi.sub.5{Li[SiO.sub.4]}.sub.2], Z. Anorg. Allg. Chem., 1991, 592, 93-105). Peaks in the X-ray powder diffractogram V which can be assigned to the secondary phase Li.sub.4SiO.sub.4 are identified by asterisks.
(82) FIG. 66 shows various optical properties of the fifth exemplary embodiment of the phosphor according to the present disclosure AB5 in comparison with conventional phosphors G1 and OS1. In this case, OS1 stands for a phosphor of the formula (Sr,Ba).sub.2SiO.sub.4:Eu and G1 stands for a phosphor of the formula Lu.sub.3(Al,Ga).sub.5O.sub.12:Ce. In comparison with the phosphors G2 and OS2, the phosphors G1 and OS1 have a different Eu and Ce content, respectively, in order in each case to obtain the same dominant wavelength as the exemplary embodiment AB5. All three phosphors exhibit a similar dominant wavelength. In this case, however, the phosphor according to the present disclosure AB5 exhibits a significantly higher luminous efficiency (LER) and a significantly higher color purity. This leads to an improved color saturation, whereby a higher color space coverage can be achieved, and to an improved overall efficiency. The reason for the improved properties is the full width at half maximum of the fourth exemplary embodiment AB5 having the formula (Rb.sub.0.5Li.sub.0.5)Li.sub.3SiO.sub.4 of the phosphor according to the present disclosure in comparison with the conventional phosphors. The high luminous efficiency increases the efficiency of green conversion LEDs having partial or full conversion in comparison with green conversion LEDs comprising known green phosphors having a comparable peak wavelength.
(83) FIG. 67 shows a comparison of the emission spectra of the fifth exemplary embodiment AB5 of the phosphor according to the present disclosure in comparison with the conventional phosphors G1 and OS1 described under FIG. 66.
(84) FIG. 68 illustrates the emission spectrum of the first exemplary embodiment AB1 having the molecular formula NaLi.sub.3SiO.sub.4:Eu and of the sixth exemplary embodiment AB6 having the molecular formula Na.sub.0.97Ca.sub.0.03Li.sub.2.94Al.sub.0.09Si.sub.0.97O.sub.3.88N.sub.0.12:Eu. The wavelength in nanometers is plotted on the x-axis and the emission intensity in percent is plotted on the y-axis. For measuring the emission spectrum, the phosphors according to the present disclosure were excited with primary radiation having a wavelength of 400 nm (ABI) and 460 nm (AB6). The phosphor AB1 has a full width at half maximum of 32 nm or 1477 cm.sup.−1 and a dominant wavelength of 473 nm; the peak wavelength is approximately 469 nm. The phosphor AB6 has a full width at half maximum of 72.8 nm, a dominant wavelength of 548 nm; the peak wavelength is approximately 516.9 nm.
(85) The color locus of AB6 is at the following coordinates CIE-x=0.301 and CIE-y=0.282 in the CIE standard chromaticity diagram from 1931. The luminous efficiency of AB6 is 432.8 lm/W. The different properties of AB1 and AB6, in particular the peak wavelength of Na.sub.0.97Ca.sub.0.03Li.sub.2.94Al.sub.0.09Si.sub.0.97O.sub.3.88N.sub.0.12:Eu shifted into the longer-wavelength range in comparison with NaLi.sub.3SiO.sub.4:Eu, are due to a greater nephelauxetic effect of the nitrogen atoms surrounding the activator ions, here the Eu.sup.2+ ions, in the mixed phase Na.sub.0.97Ca.sub.0.03Li.sub.2.94Al.sub.0.09Si.sub.0.97O.sub.3.88N.sub.0.12:Eu. The higher the proportion of nitrogen in the vicinity of the activator ions, the longer the peak wavelength. As a result, with an increasing nitrogen content and thus with a rising value for y* in the phosphor Na.sub.1−y*Ca.sub.y*Li.sub.3−2y*Al.sub.3y*Si.sub.1−yO.sub.4−4y*N.sub.4y*:Eu, the peak wavelength can be shifted within the visible range of the electromagnetic spectrum, in particular in a range of between 470 nm and 670 nm. The phosphor is thus suitable in particular for lighting devices or conversion LEDs in which phosphors having very specific properties are required (so-called “color on demand” applications).
(86) FIG. 69 shows the emission spectra of AB6 (excitation wavelength 460 nm) and four garnet phosphors as comparative examples (excitation wavelength in each case 460 nm; 440 nm in the case of Y.sub.3Al.sub.3Ga.sub.2O.sub.12:Ce). In comparison with the known garnet phosphors Y.sub.3Al.sub.5O.sub.12:Ce, Y.sub.3Al.sub.3Ga.sub.2O.sub.12:Ce and Lu.sub.3Al.sub.5O.sub.12:Ce, the exemplary embodiment according to the present disclosure AB6 has a peak wavelength shifted to shorter wavelengths and a smaller full width at half maximum. A similar peak wavelength to AB6 is exhibited by Lu.sub.3Al.sub.3Ga.sub.2O.sub.12:Ce. In comparison with the garnet phosphors Y.sub.3Al.sub.5O.sub.12:Ce, Y.sub.3Al.sub.3Ga.sub.2O.sub.12:Ce and Lu.sub.3Al.sub.5O.sub.12:Ce, the peak wavelength of AB6 and Lu.sub.3Al.sub.3Ga.sub.2O.sub.12:Ce lies nearer to the blue spectral range, in which in conventional conversion LEDs a spectral gap may disadvantageously be found, in which no or only very little light is emitted. Said spectral gap results in poor color rendering. Therefore, Lu.sub.3Al.sub.3Ga.sub.2O.sub.12:Ce is often used to reduce the spectral gap. In comparison with Lu.sub.3Al.sub.3Ga.sub.2O.sub.12:Ce, however, the sixth exemplary embodiment Na.sub.0.97Ca.sub.0.03Li.sub.2.94Al.sub.0.09Si.sub.0.97O.sub.3.88N.sub.0.12:Eu has a significantly smaller full width at half maximum and, owing to the smaller full width at half maximum, a greater color purity. An additional factor is that the exemplary embodiment according to the present disclosure AB6 has a higher overlap with the eye sensitivity curve, thus resulting in a higher luminous efficiency. A comparison of the optical data is shown in FIG. 70. The percentages indicated between parentheses reflect the changes in the values in comparison with Lu.sub.3Al.sub.3Ga.sub.2O.sub.12:Ce. The conversion of the UV or blue primary radiation into a secondary radiation having a wavelength in the green range of the electromagnetic spectrum (peak wavelength of 516.9 nm) increases the efficiency of a conversion LED. In comparison with the primary radiation, the peak wavelength of the secondary radiation is nearer to the eye sensitivity maximum at 555 nm, as a result of which the emitted radiation has a higher overlap with the eye sensitivity curve and is thus perceived as brighter. Conversion LEDs comprising the phosphor in particular in combination with a green and red phosphor are suitable in particular for white conversion LEDs, for example for general lighting. In particular, a white overall radiation having a high color temperature can be generated.
(87) FIG. 71 shows the tetragonal crystal structure of the phosphor Na.sub.0.97Ca.sub.0.03Li.sub.2.94Al.sub.0.09Si.sub.0.97O.sub.3.88N.sub.0.12:Eu in a schematic illustration along the crystallographic c-axis. The structure was determined by X-ray analysis of a single crystal of the phosphor. The hatched circles represent the mixed occupied positions for the Na and Ca atoms. The hatched regions represent the mixed occupied Li/Si/Al—O/N tetrahedra. The crystal structure corresponds to the crystal structure of NaLi.sub.3SiO.sub.4:Eu (see FIG. 8). The crystal structure is isotypic with respect to that of CaLiAl.sub.3N.sub.4:Eu, described in P. Pust, A. S. Wochnik, E. Baumann, P. J. Schmidt, D. Wiechert, C. Scheu, W. Schnick, Ca[LiAl.sub.3N.sub.4]:Eu.sup.2+—A Narrow-Band Red-Emitting Nitridolithoaluminate, Chemistry of Materials 2014 26, 3544-3549.
(88) FIG. 72 shows crystallographic data of Na.sub.0.97Ca.sub.0.03Li.sub.2.94Al.sub.0.09Si.sub.0.97O.sub.3.88N.sub.0.12:Eu.
(89) FIG. 73 shows atomic positions in the structure of Na.sub.0.97Ca.sub.0.03Li.sub.2.94Al.sub.0.09Si.sub.0.97O.sub.3.88N.sub.0.12:Eu.
(90) FIG. 74 illustrates the emission spectrum of the seventh exemplary embodiment AB7 of the phosphor according to the present disclosure having the molecular formula (Na.sub.0.25K.sub.0.5Li.sub.0.25)Li.sub.3SiO.sub.4:Eu.sup.2+. For measuring the emission spectrum, a single crystal of the phosphor according to the present disclosure was excited with a primary radiation having a wavelength of 460 nm. The phosphor has a full width at half maximum of less than 50 nm, a peak wavelength of 532 nm, a dominant wavelength of 540.3 nm and a color locus in the CIE color space having the coordinates CIE-x: 0.235 and CIE-y: 0.640. The narrow full width at half maximum of the phosphor leads to a saturated green emission of the phosphor. The phosphor (K.sub.1−r″−r′″Na.sub.r″Li.sub.r′″).sub.1(TA).sub.3(TA) TD).sub.1(XB).sub.4:E or (K.sub.1−r″−r′″Na.sub.r″Li.sub.r′″).sub.1Li.sub.3SiO.sub.4:E where 0<r″<0.5 and 0<r′″<0.5, in particular (Na.sub.0.25K.sub.0.5Li.sub.0.25)Li.sub.3SiO.sub.4:Eu.sup.2+, is therefore particularly attractive for its use in a conversion LED in which a narrowband emission in the green spectral range is required, such as for the backlighting of LCD displays.
(91) FIG. 75 shows the emission spectra of AB7 and a β-SiAlON:Eu (BS) as comparative example. The phosphors have comparable peak and dominant wavelengths and color purities, although AB7 exhibits a smaller full width at half maximum and, associated therewith, a greater luminous efficiency and higher color purity. This leads to an improved color saturation, as a result of which it is possible to achieve a higher color space coverage, and to an improved overall efficiency. The reason for the improved properties is the small full width at half maximum of the seventh exemplary embodiment AB7 having the formula (Na.sub.0.25K.sub.0.50Li.sub.0.25)Li.sub.3SiO.sub.4:Eu.sup.2+ of the phosphor according to the present disclosure in comparison with the known phosphor BS. The high luminous efficiency increases the efficiency of green conversion LEDs having partial or full conversion in comparison with green conversion LEDs comprising known green phosphors having a comparable dominant and/or peak wavelength. The optical data of the phosphors AB7 and BS are shown in FIG. 76. The phosphor K.sub.1−r″−r′″Na.sub.r″Li.sub.r′″).sub.1(TA).sub.3(TD).sub.1(XB).sub.4:E or (K.sub.1−r″−r′″Na.sub.r″Li.sub.r′″).sub.1Li.sub.3SiO.sub.4:E where 0<r″<0.5 and 0<r′″<0.5, in particular (Na.sub.0.25K.sub.0.5Li.sub.0.25)Li.sub.3SiO.sub.4:Eu.sup.2+, thus proves to be very suitable for applications in which a saturated green hue is desired, as in backlighting applications.
(92) FIG. 77 shows the monoclinic crystal structure of the phosphor (Na.sub.0.25K.sub.0.50Li.sub.0.25)Li.sub.3SiO.sub.4:Eu.sup.2+ in a schematic illustration along the crystallographic b-axis. The black circles represent Na atoms, the hatched circles represent K atoms and the circles enclosing white areas represent the Li atoms. The phosphor AB7 crystallizes in the same space group, C.sub.2/m, as the fifth exemplary embodiment (Rb.sub.0.5Li.sub.0.5)Li.sub.3SiO.sub.4:Eu.sup.2+ with comparable lattice parameters. The crystal structures of the phosphors (Na.sub.0.25K.sub.0.50Li.sub.0.25)Li.sub.3SiO.sub.4:Eu and (Rb.sub.0.5Li.sub.0.5)Li.sub.3SiO.sub.4:Eu.sup.2+ have identical (Li.sub.3SiO.sub.4) structural units. The occupation of the channels within these structural units is different in this case, however. (Rb.sub.0.5Li.sub.0.5)Li.sub.3SiO.sub.4:Eu.sup.2+ contains two types of channels, wherein one channel is occupied only by Rb and the other is occupied only by Li, while (Na.sub.0.25K.sub.0.50Li.sub.0.25)Li.sub.3SiO.sub.4:Eu also contains two types of channels, wherein one channel is occupied only by K and the other channel is occupied only by Li and Na. The arrangement of Na and K in (Na.sub.0.25K.sub.0.50Li.sub.0.25)Li.sub.3SiO.sub.4:Eu is similar to the arrangement in CsKNaLi(Li.sub.3SiO.sub.4).sub.4, as described in K. Bernet, R. Hoppe, Z. Anorg. Chem., 1991, 592, 93-105. The exact arrangement of Na and Li within a channel cannot be ascertained by means of X-ray diffraction. A statistical arrangement is taken as a basis in the present case. The crystal structure of AB7 is a crystal structure derived from the UCr.sub.4C.sub.4 structure type with a higher degree of ordering.
(93) FIG. 78 shows the arrangement of Li, Na and K within the channels of the (Li.sub.3SiO.sub.4) structural units for (Na.sub.0.25K.sub.0.50Li.sub.0.25)Li.sub.3SiO.sub.4:Eu. The black circles represent Na atoms, the hatched circles represent K atoms and the circles enclosing white areas represent the Li atoms. The arrangement is shown along the crystallographic c-axis.
(94) FIG. 79 shows crystallographic data of (Na.sub.0.25K.sub.0.50Li.sub.0.25)Li.sub.3SiO.sub.4:Eu.
(95) FIG. 80 shows atomic positions in the structure of (Na.sub.0.25K.sub.0.50Li.sub.0.25)Li.sub.3SiO.sub.4:Eu.
(96) FIG. 81 shows anisotropic displacement parameters of (Na.sub.0.25K.sub.0.50Li.sub.0.25)Li.sub.3SiO.sub.4:Eu.
(97) FIG. 82 illustrates the emission spectrum of the eighth exemplary embodiment AB8 of the phosphor according to the present disclosure having the molecular formula (Na.sub.0.5Rb.sub.0.5)Li.sub.3SiO.sub.4:Eu.sup.2+. The wavelength in nm is plotted on the x-axis and the emission intensity in percent is plotted on the y-axis. For measuring the emission spectrum, a powder of the phosphor according to the present disclosure was excited with a primary radiation having a wavelength of 400 nm. The phosphor has a peak wavelength of approximately 525 nm and a dominant wavelength of 531 nm. The full width at half maximum is less than 45 nm and the color locus in the CIE color space lies at the coordinates CIE-x: 0.211 and CIE-y: 0.671.
(98) FIG. 83 illustrates the emission spectrum of the eighth exemplary embodiment AB8 of the phosphor according to the present disclosure having the molecular formula (Na.sub.0.5Rb.sub.0.5)Li.sub.3SiO.sub.4:Eu.sup.2+. For measuring the emission spectrum, a powder of the phosphor according to the present disclosure was excited with a primary radiation having a wavelength of 460 nm. The phosphor has a full width at half maximum of less than 45 nm, a peak wavelength of 528 nm, a dominant wavelength of 533 nm and a color locus in the CIE color space having the coordinates CIE-x: 0.212 and CIE-y: 0.686. The narrow full width at half maximum of the phosphor results in a saturated green emission of the phosphor. On account of the small full width at half maximum, the phosphor (Rb.sub.r*Na.sub.1−r*).sub.1(TA).sub.3(TD).sub.1(XB).sub.4:E or Rb.sub.r*Na.sub.1−r*).sub.1Li.sub.3SiO.sub.4:E where 0.4≤r*<1.0, in particular (Na.sub.0.5Rb.sub.0.5)Li.sub.3SiO.sub.4:Eu.sup.2+, is particularly attractive for the use thereof in a conversion LED in which a narrowband emission in the green spectral range is required, as for the backlighting of LCD displays.
(99) FIG. 84 shows a normalized Kubelka-Munk function (K/S), plotted against the wavelength λ in nm, for the eighth exemplary embodiment (AB8) of the phosphor according to the present disclosure. The phosphor according to the present disclosure can be efficiency excited with a primary radiation in the range of between 330 nm and 500 nm, advantageously 340 nm to 460 nm, particularly advantageously 350 nm to 450 nm. As a result, the phosphor is suitable in particular for backlighting applications, using a semiconductor chip with a primary radiation in the near UV range or blue range of the electromagnetic spectrum.
(100) FIG. 85 shows a comparison of the emission spectra of the eighth exemplary embodiment AB8 of the phosphor according to the present disclosure in comparison with the conventional phosphors ClS and OS1 described under FIG. 86.
(101) FIG. 86 shows various optical properties of the eighth exemplary embodiment of the phosphor according to the present disclosure AB8 in comparison with conventional phosphors ClS and OS1. In this case, OS1 stands for a phosphor of the formula (Sr,Ba).sub.2SiO.sub.4:Eu, and ClS stands for Ca.sub.7.8Eu.sub.0.2Mg(SiO.sub.4).sub.4Cl.sub.2. All three phosphors exhibit a similar dominant wavelength. In this case, however, the phosphor AB8 according to the present disclosure exhibits a significantly higher luminous efficiency (LER). This leads to an improved color saturation, as a result of which it is possible to achieve a higher color space coverage, and to an improved overall efficiency. The reason for the improved properties is the small full width at half maximum of the eighth exemplary embodiment AB8 having the formula (Na.sub.0.5Rb.sub.0.5)Li.sub.3SiO.sub.4:Eu.sup.2+ of the phosphor according to the present disclosure in comparison with the conventional phosphors. The high luminous efficiency increases the efficiency of green conversion LEDs having partial or full conversion in comparison with green conversion LEDs comprising known green phosphors having a comparable dominant and/or peak wavelength.
(102) In FIG. 87, the relative brightness in % is plotted against the temperature in ° C. As is evident, the exemplary embodiment AB8 of the phosphor according to the present disclosure exhibits a high thermal stability. FIG. 87 shows the thermal quenching behavior of the phosphor according to the present disclosure AB8 (represented as open squares) in comparison with a conventional phosphor OS1 of the formula (Sr,Ba).sub.2SiO.sub.4:Eu (represented as filled rhombi). The phosphors were excited with a blue primary radiation having a wavelength of 400 nm for the phosphor according to the present disclosure AB8 and 460 nm for OS1 at various temperatures from 25 to 225° C. and their emission intensity was recorded in the process. It is clearly evident that the phosphor according to the present disclosure AB8 has a significantly smaller loss of emission intensity at typical temperatures that prevail in a conversion LED, in particular temperatures above 140° C. The phosphor can thus advantageously be used even at higher operating temperatures in conversion LEDs. Starting from 125° C., AB8 exhibits a significantly smaller loss of emission intensity in comparison with OS1. Moreover, AB8 at a temperature of 225° C. still exhibits an emission intensity of 90% in comparison with the emission intensity of 100% at 25° C. The emission intensity at 225° C. is more than twice as high as the emission intensity of OS1 at 225° C.
(103) FIG. 88 shows the monoclinic crystal structure of the phosphor (Na.sub.0.5Rb.sub.0.5)Li.sub.3SiO.sub.4:Eu.sup.2+ in a schematic illustration. The black circles represent Rb atoms and the circles enclosing white areas represent Na atoms. The phosphor AB8 crystallizes in the same space group, C2/m, as the fifth exemplary embodiment (Rb.sub.0.5Li.sub.0.5)Li.sub.3SiO.sub.4:Eu.sup.2+ and the sixth exemplary embodiment (Na.sub.0.25K.sub.0.50Li.sub.0.25)Li.sub.3SiO.sub.4:Eu with comparable lattice parameters. The crystal structures of the phosphors (Na.sub.0.5Rb.sub.0.5)Li.sub.3SiO.sub.4:Eu.sup.2+, (Na.sub.0.25K.sub.0.50Li.sub.0.25)Li.sub.3SiO.sub.4:Eu and (Rb.sub.0.5Li.sub.0.5)Li.sub.3SiO.sub.4:Eu.sup.2+ have the same (Li.sub.3SiO.sub.4) structural units. The (Li.sub.3SiO.sub.4) structural units are SiO.sub.4 and LiO.sub.4 tetrahedra, wherein oxygen occupies the corners and Li and Si, respectively, occupy the center of the tetrahedron. The occupation of the channels within these structural units is different in this case, however. (Rb.sub.0.5Li.sub.0.5)Li.sub.3SiO.sub.4:Eu.sup.2+ contains two types of channels, wherein one channel is occupied only by Rb and the other is occupied only by Li, (Na.sub.0.25K.sub.0.50Li.sub.0.25)Li.sub.3SiO.sub.4:Eu also contains two types of channels, wherein one channel is occupied only by K and the other channel is occupied only by Li and Na, and (Rb.sub.0.5Na.sub.0.5)Li.sub.3SiO.sub.4:Eu.sup.2+ contains two types of channels, wherein one channel is occupied only by Rb and the other channel is occupied only by Na.
(104) A crystallographic evaluation is found in FIG. 89. FIG. 89 shows a Rietveld refinement of the X-ray powder diffractogram of the eighth exemplary embodiment AB8. The diagram illustrates the superimposition of the measured reflections with the calculated reflections for (Na.sub.0.5Rb.sub.0.5)Li.sub.3SiO.sub.4:Eu, and also the differences between the measured and calculated reflections. The phosphor is contaminated with a small proportion of Na.sub.3RbLi.sub.12Si.sub.4O.sub.16.
(105) FIG. 90 shows crystallographic data of (Na.sub.0.5Rb.sub.0.5)Li.sub.3SiO.sub.4:Eu.
(106) FIG. 91 shows atomic positions in the structure of (Na.sub.0.5Rb.sub.0.5)Li.sub.3SiO.sub.4:Eu.
(107) FIG. 92 illustrates the emission spectrum of the ninth exemplary embodiment AB9 of the phosphor according to the present disclosure having the molecular formula (Rb.sub.0.25Na.sub.0.75)Li.sub.3SiO.sub.4:Eu. The wavelength in nm is plotted on the x-axis and the emission intensity in % is plotted on the y-axis. For measuring the emission spectrum, a powder of the phosphor according to the present disclosure was excited with a primary radiation having a wavelength of 400 nm. The phosphor has a peak wavelength of approximately 473 nm and a dominant wavelength of 476 nm. The full width at half maximum is at 22 nm and the color locus in the CIE color space is at the coordinates CIE-x: 0.127 and CIE-y: 0.120.
(108) FIG. 93 illustrates the emission spectrum of the ninth exemplary embodiment AB9 of the phosphor according to the present disclosure having the molecular formula (Na.sub.0.75Rb.sub.0.25)Li.sub.3SiO.sub.4:Eu.sup.2+. For measuring the emission spectrum, a powder of the phosphor according to the present disclosure was excited with a primary radiation having a wavelength of 420 nm and 440 nm. In comparison with the excitation with a primary radiation of 400 nm as shown in FIG. 92, the phosphor has an even smaller full width at half maximum of between 19 nm and 21 nm. (Na.sub.0.75Rb.sub.0.25)Li.sub.3SiO.sub.4:Eu.sup.2+ and (Na.sub.0.5K.sub.0.5)Li.sub.3SiO.sub.4:Eu.sup.2+ belong to the most narrowband Eu.sup.2+-doped phosphors known.
(109) FIG. 94 shows a normalized Kubelka-Munk function (K/S), plotted against the wavelength λ in nm, for the ninth exemplary embodiment (AB9) of the phosphor according to the present disclosure, and of BaMgAl.sub.10O.sub.17:Eu (50 mol %) (VB1) as comparative example. The phosphor according to the present disclosure can be efficiently excited with a primary radiation in the range of between 340 nm and 470 nm, advantageously 340 nm to 450 nm, particularly advantageously 340 nm to 420 nm. As a result, the phosphor (Rb.sub.r*Na.sub.1−r*).sub.1(TA).sub.3(TD).sub.1(XB).sub.4:E or Rb.sub.r*Na.sub.1−r*)Li.sub.3SiO.sub.4:E where 0<r*<0.4, in particular (Na.sub.0.75Rb.sub.0.25)Li.sub.3SiO.sub.4:Eu.sup.2+, is suitable in particular for backlighting applications, using a semiconductor chip with a primary radiation in the near UV range or blue range of the electromagnetic spectrum. As is evident, in comparison with VB1, AB9 is able to be efficiently excited even in the blue range of the electromagnetic spectrum.
(110) FIG. 95 shows a comparison of the emission spectra of the ninth exemplary embodiment AB9 of the phosphor according to the present disclosure in comparison with the conventional phosphors VB1 and VB4 described under FIG. 96, at an excitation wavelength of 400 nm.
(111) FIG. 96 shows various optical properties of the ninth exemplary embodiment of the phosphor according to the present disclosure AB9 in comparison with conventional phosphors VB1 and VB4. In this case, VB1 stands for a phosphor of the formula BaMgAl.sub.10O.sub.17:Eu and VB4 stands for (Ba.sub.0.75Sr.sub.0.25)Si.sub.2O.sub.2N.sub.2:Eu. All three phosphors exhibit a similar dominant wavelength and peak wavelength. In this case, however, the phosphor AB9 according to the present disclosure exhibits a significantly smaller full width at half maximum than the comparative examples.
(112) FIG. 97 shows the tetragonal crystal structure of the phosphor (Na.sub.0.75Rb.sub.0.25)Li.sub.3SiO.sub.4:Eu.sup.2+ in a schematic illustration. The black circles represent Rb atoms and the circles enclosing white areas represent Na atoms. The phosphor AB9 crystallizes in the same space group, I4/m, as the third exemplary embodiment (Na.sub.0.5K.sub.0.5)Li.sub.3SiO.sub.4:Eu.sup.2+. The crystal structures of the phosphors (Na.sub.0.5K.sub.0.5)Li.sub.3SiO.sub.4:Eu.sup.2+ and (Na.sub.0.75Rb.sub.0.25)Li.sub.3SiO.sub.4:Eu.sup.2+ have the same (Li.sub.3SiO.sub.4) structural units. The (Li.sub.3SiO.sub.4) structural units have SiO.sub.4 and LiO.sub.4 tetrahedra, wherein oxygen occupies the corners and Li and Si, respectively, occupy the center of the tetrahedron. The occupation of the channels within these structural units is different in the phosphors. (K.sub.0.5Na.sub.0.5)Li.sub.3SiO.sub.4:Eu.sup.2+ contains two types of channels, wherein one channel is occupied only by K and the other is occupied only by Na. (Na.sub.0.75Rb.sub.0.25)Li.sub.3SiO.sub.4:Eu.sup.2+ likewise contains two types of channels, wherein one channel is occupied only by Na and the other is occupied alternately by Na and Rb in mixed fashion.
(113) A crystallographic evaluation is found in FIG. 98. FIG. 98 shows a Rietveld refinement of the X-ray powder diffractogram of the ninth exemplary embodiment AB9. The diagram illustrates the superimposition of the measured reflections with the calculated reflections for (Na.sub.0.75Rb.sub.0.25)Li.sub.3SiO.sub.4:Eu, and also illustrates the differences between the measured and calculated reflections. The phosphor is contaminated with a small proportion of NaLi.sub.3SiO.sub.4.
(114) FIG. 99 shows crystallographic data of (Na.sub.0.75Rb.sub.0.25)Li.sub.3SiO.sub.4:Eu.
(115) FIG. 100 shows atomic positions in the structure of (Na.sub.0.75Rb.sub.0.25)Li.sub.3SiO.sub.4:Eu.
(116) In FIG. 101, the relative brightness in % is plotted against the temperature in ° C. As is evident, the exemplary embodiment AB9 of the phosphor according to the present disclosure exhibits a high thermal stability. FIG. 101 shows the thermal quenching behavior of the phosphor according to the present disclosure AB9 in comparison with a known phosphor BaMgAl.sub.10O.sub.17:Eu (VB1). The phosphors were excited with a blue primary radiation having a wavelength of 400 nm at various temperatures from 25 to 225° C. and their emission intensity between 410 nm and 780 nm was recorded in the process. It is clearly evident that the phosphor AB9 according to the present disclosure has a significantly smaller loss of emission intensity at temperatures above 100° C. At a temperature of 225° C., AB9 still exhibits an emission intensity of more than 95% in comparison with the emission intensity of 100% at 25° C.
(117) FIG. 102 illustrates the emission spectrum of the tenth exemplary embodiment AB10 of the phosphor according to the present disclosure having the molecular formula SrSiAl.sub.0.84Li.sub.2.16O.sub.1.32N.sub.2.68:Eu. For measuring the emission spectrum, a single crystal of the phosphor according to the present disclosure was excited with a primary radiation having a wavelength of 460 nm. The phosphor has a peak wavelength of approximately 628.7 nm and a dominant wavelength of 598 nm. The full width at half maximum is at 99 nm and the color locus in the CIE color space is at the coordinates CIE-x: 0.617 and CIE-y: 0.381.
(118) FIG. 103 illustrates the emission spectrum of the tenth exemplary embodiment AB10 of the phosphor according to the present disclosure having the molecular formula SrSiAl.sub.0.84Li.sub.2.16O.sub.1.32N.sub.2.68:Eu. For measuring the emission spectrum, a powder of the phosphor according to the present disclosure was excited with a primary radiation having a wavelength of 460 nm. The phosphor has a peak wavelength of approximately 632 nm and a dominant wavelength of 600 nm. The full width at half maximum is at 97.7 nm and the color locus in the CIE color space is at the coordinates CIE-x: 0.626 and CIE-y: 0.372. On account of self-absorption, the emission spectrum of the powder has a smaller full width at half maximum than the emission spectrum of the single crystal from FIG. 102.
(119) FIG. 104 shows a normalized Kubelka-Munk function (K/S), plotted against the wavelength λ in nm, for the tenth exemplary embodiment (AB10) of the phosphor according to the present disclosure. The phosphor according to the present disclosure can be efficiency excited with a primary radiation in the range of between 340 nm and 500 nm, advantageously 340 nm to 460 nm.
(120) FIG. 105 illustrates the emission spectrum of the tenth exemplary embodiment AB10 of the phosphor according to the present disclosure having the molecular formula SrSiAl.sub.0.84Li.sub.2.16O.sub.1.32N.sub.2.68:Eu and of two further exemplary embodiments (AB-10a and AB-10b) of the phosphor having the general formula Sr(Si.sub.0.25Al.sub.−1/8+r**/2Li.sub.7/8−r**/2).sub.4(O.sub.1−r**N.sub.r**).sub.4. The exemplary embodiments were produced like AB10; the weighed-in quantities are indicated in tables below.
(121) TABLE-US-00020 Weighed-in quantities of the starting materials for AB-10a Starting Substance amount/ material mmol Mass/g NaLi.sub.3SiO.sub.4 28.08 3.817 SrO 26.96 2.794 LiAlH.sub.4 84.25 3.192 Eu.sub.2O.sub.3 0.56 0.198
(122) TABLE-US-00021 Weighed-in quantities of the starting materials for AB-10b Starting Substance amount/ material mmol Mass/g NaLi.sub.3SiO.sub.4 29.82 4.052 SrO 22.50 2.331 Li.sub.3N 8.13 0.283 AlN 73.18 3.000 Eu.sub.2O.sub.3 0.95 0.334
(123) As is evident, by varying r** in the formula Sr(Si.sub.0.25Al.sub.−1/8+r**/2Li.sub.7/8−r**/2).sub.4(O.sub.1−r**N.sub.r**).sub.4, it is possible for the peak wavelength to be shifted from the yellow into the red spectral range. A comparison of optical properties of AB10, AB-10a and AB-10b is shown in FIG. 106. Known phosphors that exhibit emissions in this spectral range are α-SiAlON:Eu or (Ca,Sr,Ba).sub.2Si.sub.5N.sub.8:Eu. However, α-SiAlONs exhibit less adjustability of the peak wavelength than Sr(Si.sub.0.25Al.sub.−1/8+r**/2Li.sub.7/8−r**/2).sub.4(O.sub.1−r**N.sub.r**).sub.4 and are thus limited in their application. Although a better adjustability of the peak wavelength is exhibited by (Ca,Sr,Ba).sub.2Si.sub.5N.sub.8:Eu, the use thereof is associated with high costs as a result of expensive starting materials, such as alkaline earth metal nitrides, and high synthesis temperatures over 1400° C. The phosphor (MB)(Si.sub.0.25Al.sub.−1/8+r**/2Li.sub.7/8−r**/2).sub.4(O.sub.1−r**N.sub.r**).sub.4:E or Sr(Si.sub.0.25Al.sub.−1/8+r**/2Li.sub.7/8−r**/2).sub.4(O.sub.1−r**N.sub.r**).sub.4:E where 0.25≤r**≤1 can thus be adjusted in a targeted manner with regard to the desired color locus and/or color rendering index depending on requirements or application. Surprisingly many colors of the visible range, in particular from yellow to red, can thus be generated with just one phosphor. The phosphor is suitable in particular for conversion light-emitting diodes configured to emit a yellow to red radiation or a white radiation.
(124) FIG. 107 shows the tetragonal crystal structure of the phosphor SrSiAl.sub.0.84Li.sub.2.16O.sub.1.32N.sub.2.68:Eu in a schematic illustration along the crystallographic c-axis. The hatched circles represent Sr atoms and hatched regions represent (Li,Si,Al)(O,N).sub.4 tetrahedra. The phosphor AB10 crystallizes in the UCr.sub.4C.sub.4 structure type. The Sr atoms are situated in tetragonal channels formed by the corner- and edge-linked (Li,Si,Al)(O,N).sub.4 tetrahedra. The phosphor crystallizes in the space group I4/m.
(125) FIG. 108 shows crystallographic data of SrSiAl.sub.0.84Li.sub.2.16O.sub.1.32N.sub.2.68:Eu.
(126) FIG. 109 shows atomic positions in the structure of SrSiAl.sub.0.84Li.sub.2.16O.sub.1.32N.sub.2.68:Eu.
(127) FIG. 110 shows anisotropic displacement parameters of SrSiAl.sub.0.84Li.sub.2.16O.sub.1.32N.sub.2.68:Eu.
(128) FIG. 111 shows a crystallographic evaluation of the X-ray powder diffractogram of the tenth exemplary embodiment AB10. The diagram illustrates the superimposition of the measured reflections with the calculated reflections for SrSiAl.sub.0.84Li.sub.2.16O.sub.1.32N.sub.2.68:Eu. The upper part of the diagram shows the experimentally observed reflections (Cu Kai radiation); the lower part of the diagram shows the calculated reflection positions. The calculation was made on the basis of the structure model for SrSiAl.sub.0.84Li.sub.2.16O.sub.1.32N.sub.2.68:Eu, as described in FIGS. 107-110. Reflections of secondary phases are identified by *. The secondary phases are present in a very small proportion.
(129) FIG. 112 illustrates the emission spectrum of the eleventh exemplary embodiment AB11 of the phosphor according to the present disclosure having the molecular formula Na.sub.1−y*Eu.sub.y**Li.sub.3−2y**Al.sub.3y**Si.sub.1−y**O.sub.4−4y**N.sub.4y**:Eu where y**=0.2224 in comparison with the first exemplary embodiment AB1 NaLi.sub.3SiO.sub.4. The phosphor AB11 has a peak wavelength of approximately 613.4 nm and a dominant wavelength of 593.6 nm. The full width at half maximum is at 105 nm and the color locus in the CIE color space is at the coordinates CIE-x: 0.595 and CIE-y: 0.404. The different properties of AB1 and AB11, in particular the peak wavelength shifted into the longer-wavelength range for Na.sub.1−y**Eu.sub.y**Li.sub.3−2y**Al.sub.3y**Si.sub.1−y**O.sub.4−4y**N.sub.4y**:Eu where y**=0.2224 in comparison with NaLi.sub.3SiO.sub.4:Eu is due to a stronger nephelauxetic effect of the nitrogen atoms surrounding the activator ions, here the Eu.sup.2+ ions, in the mixed phase Na.sub.1−y**Eu.sub.y**Li.sub.3−2y**Al.sub.3y**Si.sub.1−y**O.sub.4−4y**N.sub.4y**:Eu where y**=0.2224. The higher the proportion of nitrogen in the vicinity of the activator ions, the longer the peak wavelength. As a result, with increasing nitrogen content and thus with a rising value for y** in the phosphor Na.sub.1−y*Eu.sub.y**Li.sub.3−2y**Al.sub.3y**Si.sub.1−y**O.sub.4−4y**N.sub.4y**:Eu, the peak wavelength can be shifted within the visible range of the electromagnetic spectrum, in particular in a range of between 470 nm and 670 nm. The phosphor (MA).sub.1−y***Sr.sub.y**Li.sub.3−2y***Al.sub.3y***Si.sub.1−y***O.sub.4−4y***N.sub.4y***:E or Na.sub.1−y*Eu.sub.y**Li.sub.3−2y**Al.sub.3y**Si.sub.1−y**O.sub.4−4y**N.sub.4y**:E where 0<y***<0.875 is thus suitable in particular for lighting devices or conversion LEDs in which phosphors having very specific properties are required (so-called “color on demand” applications), for example for flashing lights in a motor vehicle.
(130) Optical data for AB11 are shown in FIG. 113.
(131) FIG. 114 shows the tetragonal crystal structure of the phosphor Na.sub.1−y**Eu.sub.y**Li.sub.3−2y**Al.sub.3y**Si.sub.1−y**O.sub.4−4y**N.sub.4y**:Eu where y**=0.2224 (AB11) and in a schematic illustration along the crystallographic c-axis. The hatched circles represent Na/Eu atoms and the hatched regions represent (Li,Si,Al)(O,N).sub.4 tetrahedra. The phosphor AB11 crystallizes in the UCr.sub.4C.sub.4 structure type. The Na and Eu atoms are situated in tetragonal channels formed by the corner- and edge-linked (Li,Si,Al)(O,N).sub.4 tetrahedra. The phosphor crystallizes in the space group I4/m. The crystal structure is known e.g. for phosphors of the formula Sr[Mg.sub.2Al.sub.2N.sub.4]:Eu.sup.2+ (WO 2013/175336 A1 or P. Pust et al., Chem. Mater., 2014, 26, 6113). Surprisingly, in the present case it has been possible to show that even phosphors having a proportion of less than 87.5% nitrogen can be synthesized and are stable.
(132) FIG. 115 shows crystallographic data of Na.sub.1−y*Eu.sub.y**Li.sub.3−2y**Al.sub.3y**Si.sub.1−y**O.sub.4−4y**N.sub.4y**:Eu where y**=0.2224.
(133) FIG. 116 shows atomic positions in the structure of Na.sub.1−y**Eu.sub.y*Li.sub.3−2y**Al.sub.3y**Si.sub.1−y**O.sub.4−4y**N.sub.4y**:Eu where y**=0.2224.
(134) FIG. 117 shows anisotropic displacement parameters of Na.sub.1−y**Eu.sub.y**Li.sub.3−2y**Al.sub.3y**Si.sub.1−y**O.sub.4−4y**N.sub.4y**:Eu where y**=0.2224.
(135) FIG. 118A shows a crystallographic evaluation of the X-ray powder diffractogram of the eleventh exemplary embodiment AB11. The diagram illustrates a comparison of the measured reflections with the calculated reflections for Na.sub.1−y*Eu.sub.y**Li.sub.3−2y**Al.sub.3y**Si.sub.1−y**O.sub.4−4y**N.sub.4y**:Eu where y**=0.2224. The upper part of the diagram shows the experimentally observed reflections (Mo K.sub.α1 radiation); the lower part of the diagram shows the calculated reflection position. The calculation was made on the basis of the structure model for Na.sub.1−y*Eu.sub.y**Li.sub.3−2y**Al.sub.3y**Si.sub.1−y**O.sub.4−4y**N.sub.4y**:Eu where y**=0.2224, as described in FIGS. 114-117. The correspondence of the reflections of the calculated powder diffractogram to the reflections of the measured powder diffractogram reveals a correspondence of the crystal structure of single crystals and powders of the phosphor.
(136) FIG. 118B shows the emission spectra of Na.sub.1−y**Eu.sub.y**Li.sub.3−2y**Al.sub.3y**Si.sub.1−y**O.sub.4−4y**N.sub.4y**:Eu where y**=0.1 (AB11-1), Na.sub.1−y*Ca.sub.y*Li.sub.3−2y*Al.sub.3y*Si.sub.1−y*O.sub.4−4y*N.sub.4y*:Eu where y*=0.25 (AB6-1; AB6-2) and Na.sub.1−y***Sr.sub.y***Li.sub.3−2y***Al.sub.3y***Si.sub.1−y***O.sub.4−4y***N.sub.4y***:Eu where y***=0.25 (AB18). A comparison of the optical properties is shown in FIG. 119.
(137) FIG. 120 shows an excerpt from the CIE color space. In this excerpt, the region designated by ECE corresponds to color loci for flashing lights in the exterior region of a motor vehicle in the yellow or yellow-orange color range which correspond to the ECE regulations (ECE:Economic Commission for Europe). The ECE regulations are a catalog of internationally agreed, standardized technical specifications for motor vehicles and for parts and items of equipment of motor vehicles. Furthermore, the color loci of the eleventh exemplary embodiment AB11 and of a comparative example (Sr,Ca,Ba).sub.2Si.sub.5N.sub.8:Eu (Comp 258) are shown. The color loci of both phosphors lie within the ECE region and are therefore suitable for the use of said phosphors in conversion LEDs for flashing lights in motor vehicles. In contrast to (Sr,Ca,Ba).sub.2Si.sub.5N.sub.8:Eu, the phosphor according to the present disclosure AB11 can be produced at lower temperatures. A yellow or yellow-orange conversion LED comprising AB11 (full conversion) is much more efficient and more temperature-stable in comparison with a yellow or yellow-orange LED, based on InGaAlP.
(138) FIG. 121 shows the color loci of AB11 and Comp 258.
(139) FIG. 122 illustrates the emission spectrum of a single crystal of the twelfth exemplary embodiment AB12 of the phosphor according to the present disclosure having the molecular formula SrLi.sub.3−2x**Al.sub.1+2x**O.sub.4−4x**N.sub.4x**:Eu where x**=0.2014 in comparison with a comparative example (Ca,Sr,Ba).sub.2SiO.sub.4:Eu. The phosphor AB12 has a peak wavelength of approximately 580.3 nm and a dominant wavelength of 576.5 nm. The full width at half maximum is at 80 nm and the color locus in the CIE color space is at the coordinates CIE-x: 0.486 and CIE-y: 0.506. A comparison of the optical data of AB12 and (Ca,Sr,Ba).sub.2SiO.sub.4:Eu is illustrated in FIG. 123. (MB)Li.sub.3−2x**Al.sub.1+2x**O.sub.4−4x**N.sub.4x**:Eu or SrLi.sub.3−2x**Al.sub.1+2x**O.sub.4−4x*N.sub.4x*:Eu where 0<x**<0.875, in particular where x**=0.2014, is suitable for use in colored conversion LEDs in which the primary radiation is completely or almost completely converted into secondary radiation and is thus usable in particular for “color on demand” applications. As illustrated in FIG. 123, a conversion LED comprising AB12 has a higher luminous efficiency than a conversion LED comprising (Ca,Sr,Ba).sub.2SiO.sub.4:Eu.
(140) FIG. 124 shows simulated emission spectra of conversion LEDs. Emission spectra of conversion LEDs with a primary radiation of 442 nm with the twelfth exemplary embodiment AB12 and phosphors as comparative examples are shown. White emission spectra in which the overall radiation is composed of the primary radiation and the respective secondary radiation are shown. The optical data are illustrated in FIG. 125. On account of the small full width at half maximum of AB12 in comparison with the comparative examples, the conversion LED comprising the phosphor according to the present disclosure AB12 has a higher luminous efficiency (LER) since the overlap with the eye sensitivity curve is greater than in the comparative examples. (MB)Li.sub.3−2x**Al.sub.1+2x**O.sub.4−4x**N.sub.4x**:Eu or SrLi.sub.3−2x**Al.sub.1+2x**O.sub.4−4x**N.sub.4x**:Eu where 0<x**<0.875, in particular the twelfth exemplary embodiment, is thus suitable in particular for use as sole phosphor in a conversion LED for generating warm-white overall radiation, in particular having a color temperature of 3400 K±100 K in combination with a primary radiation in the UV to blue range, for example with a layer sequence based on InGaN. Color temperatures of 3400 K±100 K with color loci near the Planckian locus are not achieved with the use of Y.sub.3Al.sub.5O.sub.12:Ce. Although the use of modifications of Y.sub.3Al.sub.5O.sub.12:Ce, such as (Y,Lu,Gd,Tb).sub.3(Al,Ga).sub.5O.sub.12:Ce (FIG. 125), leads to the desired color loci and color temperatures, the luminous efficiency is lower than with the use of Y.sub.3Al.sub.5O.sub.12:Ce and the thermal quenching behavior is higher. Orthosilicates such as (Ca,Sr,Ba).sub.2SiO.sub.4:Eu are thermally and chemically less stable in comparison with Y.sub.3Al.sub.5O.sub.12:Ce and additionally have a poorer luminous efficiency in comparison with a conversion LED comprising AB12.
(141) FIG. 114 and FIG. 160 show the tetragonal crystal structure of the phosphor SrLi.sub.3−2x**Al.sub.1+2x**O.sub.4−4x**N.sub.4x**:Eu where x**=0.2014 (AB12) in a schematic illustration along the crystallographic c-axis. The hatched circles represent Sr atoms and hatched regions represent (Li,Al)(O,N).sub.4 tetrahedra. The phosphor AB12 crystallizes in the UCr.sub.4C.sub.4 structure type. The phosphor crystallizes in the space group I4/m. The crystal structure is known e.g. for phosphors of the formula Sr[Mg.sub.2Al.sub.2N.sub.4]:Eu.sup.2+ (WO 2013/175336 A1 or P. Pust et al., Chem. Mater., 2014, 26, 6113). The (Li,Al)(O,N).sub.4 tetrahedra form tetragonal channels in which the Sr atoms are arranged. Surprisingly, in the present case it has been possible to show that even phosphors having a proportion of less than 87.5% nitrogen can be synthesized and are stable. The phosphors of the formula SrLi.sub.3−2x**Al.sub.1+2x**O.sub.4−4x**N.sub.4x**:Eu where x**≥0.1250 crystallize in this crystal type, which has been able to be shown on the basis of the exemplary embodiments AB12-1 to AB12-8. With increasing x**, the volume of the unit cell increases and the peak wavelength is shifted to longer wavelengths.
(142) FIG. 126 shows crystallographic data of SrLi.sub.3−2x*Al.sub.1+2x**O.sub.4−4x**N.sub.4x**:Eu where x**=0.2014 (AB12).
(143) FIG. 127 shows atomic positions in the structure of SrLi.sub.3−2x**Al.sub.1+2x**O.sub.4−4x**x****:Eu where x**=0.2014 (AB12).
(144) FIG. 128 shows anisotropic displacement parameters of SrLi.sub.3−2x**Al.sub.1+2x**O.sub.4−4x**x****:Eu where x**=0.2014 (AB12).
(145) FIG. 129 illustrates the emission spectrum of AB13 of the phosphor according to the present disclosure having the molecular formula (Cs.sub.0.25Na.sub.0.25K.sub.0.25Li.sub.0.25)Li.sub.3SiO.sub.4:Eu.sup.2+. For measuring the emission spectrum, a powder of the phosphor according to the present disclosure was excited with a primary radiation having a wavelength of 400 nm. The phosphor has a full width at half maximum of 46 nm, a peak wavelength of 530 nm and a dominant wavelength of 532 nm. The color locus is at CIE-x: 0.222 and CIE-y: 0.647. The optical properties are similar to those of the eighth exemplary embodiment. The peak at approximately 490 nm is probably attributable to a contamination by CsNa.sub.2K(Li.sub.3SiO.sub.4).sub.4:Eu.sup.2+.
(146) FIG. 130 shows a normalized Kubelka-Munk function (K/S), plotted against the wavelength λ in nm, for AB13. The phosphor can be efficiently excited with a primary radiation in the blue range.
(147) FIG. 131 illustrates the emission spectrum of AB14 of the phosphor according to the present disclosure having the molecular formula (Cs.sub.0.25Na.sub.0.5K.sub.0.25)Li.sub.3SiO.sub.4:Eu.sup.2+. For measuring the emission spectrum, a powder of the phosphor according to the present disclosure was excited with a primary radiation having a wavelength of 400 nm. The phosphor has a full width at half maximum of 26 nm, a peak wavelength of 486 nm and a dominant wavelength of 497 nm. The color locus is at CIE-x: 0.138 and CIE-y: 0.419.
(148) FIG. 132 shows a normalized Kubelka-Munk function (K/S), plotted against the wavelength λ in nm, for AB14. The phosphor can be efficiently excited with a primary radiation in the blue range.
(149) FIG. 133 illustrates the emission spectrum of AB15 of the phosphor according to the present disclosure having the molecular formula (Rb.sub.0.25Na.sub.0.5K.sub.0.25)Li.sub.3SiO.sub.4:Eu.sup.2+. For measuring the emission spectrum, a powder of the phosphor according to the present disclosure was excited with a primary radiation having a wavelength of 400 nm. The phosphor has a full width at half maximum of 27 nm, a peak wavelength of 480 nm and a dominant wavelength of 490 nm. The color locus is at CIE-x: 0.139 and CIE-y: 0.313. The peak at approximately 530 nm is probably attributable to a contamination by RbNa(Li.sub.3SiO.sub.4).sub.2 or K.sub.2NaLi(Li.sub.3SiO.sub.4).sub.4.
(150) FIG. 134 shows a normalized Kubelka-Munk function (K/S), plotted against the wavelength λ in nm, for AB15. The phosphor can be efficiently excited with a primary radiation in the blue range.
(151) FIG. 135 illustrates the emission spectrum of AB16 of the phosphor according to the present disclosure having the molecular formula (Cs.sub.0.25Na.sub.0.25Rb.sub.0.25Li.sub.0.25)Li.sub.3SiO.sub.4:Eu.sup.2+. For measuring the emission spectrum, a powder of the phosphor according to the present disclosure was excited with a primary radiation having a wavelength of 400 nm. The phosphor has a full width at half maximum of 24 nm, a peak wavelength of 473 nm, and a dominant wavelength of 489 nm. The peak at approximately 530 nm is probably attributable to a contamination by RbNa(Li.sub.3SiO.sub.4).sub.2.
(152) The optical properties of AB14, AB15 and AB16 are similar to those of AB9 and AB3.
(153) FIG. 136 shows a normalized Kubelka-Munk function (K/S), plotted against the wavelength λ in nm, for AB16. The phosphor can be efficiently excited with a primary radiation in the blue range.
(154) FIG. 137 shows the tetragonal crystal structure of AB13 of the phosphor according to the present disclosure having the molecular formula (Cs.sub.0.25Na.sub.0.25K.sub.0.25Li.sub.0.25)Li.sub.3SiO.sub.4:Eu.sup.2+. The black circles represent Cs atoms, the circles enclosing white areas represent Li atoms, the circles with ruled lines represent K atoms and the checked circles represent Na atoms. The crystal structure is similar to the crystal structure of the ninth exemplary embodiment AB9; AB13 crystallizes in the same space group, I4/m. The (Li.sub.3SiO.sub.4) structural units have SiO.sub.4 and LiO.sub.4 tetrahedra, wherein oxygen occupies the corners and Li and Si, respectively, occupy the center of the tetrahedron. (Cs.sub.0.25Na.sub.0.25K.sub.0.25Li.sub.0.25)Li.sub.3SiO.sub.4:Eu.sup.2+ contains two types of channels within the (Li.sub.3SiO.sub.4) structural units, wherein one channel is occupied by Na and Li and the other is occupied alternately by Cs and K. The arrangement of Na and Li within one channel corresponds to that of AB7. The exact arrangement of Na and Li within one channel cannot be ascertained by means of X-ray diffraction.
(155) FIG. 138 shows the tetragonal crystal structure of AB14 of the phosphor according to the present disclosure having the molecular formula (Cs.sub.0.25Na.sub.0.5K.sub.0.25)Li.sub.3SiO.sub.4:Eu.sup.2+. The black circles represent Cs atoms, the circles with ruled lines represent K atoms and the checked circles represent Na atoms. The crystal structure is similar to the crystal structure of the ninth exemplary embodiment AB9; AB13 crystallizes in the same space group I4/m. The (Li.sub.3SiO.sub.4) structural units have SiO.sub.4 and LiO.sub.4 tetrahedra, wherein oxygen occupies the corners and Li and Si, respectively, occupy the center of the tetrahedron. (Cs.sub.0.25Na.sub.0.5K.sub.0.25)Li.sub.3SiO.sub.4:Eu.sup.2+ contains two types of channels within the (Li.sub.3SiO.sub.4) structural units, wherein one channel is occupied by Na and the other is occupied alternately by Cs and K.
(156) FIG. 139 shows the tetragonal crystal structure of AB15 of the phosphor according to the present disclosure having the molecular formula (Rb.sub.0.25Na.sub.0.5K.sub.0.25)Li.sub.3SiO.sub.4:Eu.sup.2+. The black circles represent Rb atoms, the circles with ruled lines represent K atoms and checked circles represent Na atoms. The crystal structure is isostructural with respect to that of AB14, wherein the positions of the Cs atoms are occupied by Rb atoms.
(157) FIG. 140 shows the tetragonal crystal structure of AB16 of the phosphor according to the present disclosure having the molecular formula (Cs.sub.0.25Na.sub.0.25Rb.sub.0.25Li.sub.0.25)Li.sub.3SiO.sub.4:Eu.sup.2+. The black circles represent Cs atoms, the circles with ruled lines represent Rb atoms, the checked circles represent Na atoms and the white circles represent Li atoms. The crystal structure is isostructural with respect to that of AB13, wherein the positions of the K atoms are occupied by Rb atoms.
(158) FIGS. 141-144 each show a Rietveld refinement of the X-ray powder diffractogram of AB13 (FIG. 141), of AB14 (FIG. 142), of AB15 (FIG. 143) and of AB16 (FIG. 144). The diagram illustrates the superimposition of the measured reflections with the calculated reflections, and also the differences between the measured and calculated reflections.
(159) FIG. 145 shows crystallographic data and FIG. 146 shows atomic positions of AB13.
(160) FIG. 147 shows crystallographic data and FIG. 148 shows atomic positions of AB14.
(161) FIG. 149 shows crystallographic data and FIG. 150 shows atomic positions of AB15.
(162) FIG. 151 shows crystallographic data and FIG. 152A shows atomic positions of AB16.
(163) FIG. 152B shows the emission spectrum of single crystals of the phosphors AB12-1 and AB12-2 of the phosphor according to the present disclosure having the molecular formulae SrLi.sub.3−2x**Al.sub.1+2x**O.sub.4−4x**N.sub.4x**:Eu.sup.2+ where x**=0.125 (AB12-1) and x**=0.1375 (AB12-2). The optical properties are shown in FIG. 153.
(164) FIG. 154 shows the emission spectrum of a single crystal of the phosphor SrLi.sub.3−2x**Al.sub.1+2x** O.sub.4−4x**N.sub.4x**:Eu.sup.2+ where x**<0.125. The phosphors SrLi.sub.3−2x**Al.sub.1+2x**O.sub.4−4x**N.sub.4x**:Eu.sup.2+ where x**<0.125 have a smaller full width at half maximum than phosphors where x**≥0.125. The optical properties are shown in FIG. 155. The crystal structure of phosphors of the formula SrLi.sub.3−2x**Al.sub.1+2x**O.sub.4−4x**N.sub.4x*:Eu.sup.2+ where x**<0.125 is related to the UCr.sub.4C.sub.4 structure type, although reflections in single crystal diffraction data indicate a higher degree of ordering. This results in a crystal structure having a higher degree of ordering that is derived from the UCr.sub.4C.sub.4 structure type. Surprisingly, phosphors having a higher oxygen content exhibit a higher degree of ordering within the crystal structure. The smaller full width at half maximum is attributable to the higher degree of ordering of the crystal structure.
(165) FIG. 156 illustrates the peak wavelength λpeak in nm plotted against the cell volume of the unit cell of the crystal structure of phosphors of the formula SrLi.sub.3−2x**Al.sub.1+2x**O.sub.4−4x**N.sub.4x**:Eu where x**≥0.1250 for powders and single crystals of SrLi.sub.3−2x**Al.sub.1+2x**O.sub.4−4x**N.sub.4x:Eu having different proportions of x**. The differences in the peak wavelengths in the measurement of powders and single crystals are caused by reabsorption effects in the powder measurement, which can lead to a long-wave shift in the observed peak wavelength. The peak wavelengths can be adjusted by adapting the cell volume of the unit cell. As x** rises, the cell volume of the unit cell increases and at the same time the peak wavelength is shifted into the longer-wavelength range. Advantageously, by varying x**≥0.125, it is possible for the peak wavelength to be shifted from the green into the red spectral range. The peak wavelengths and cell volumes (V) for various proportions x** are shown in FIG. 157. As a result, the phosphor of the general molecular formula SrLi.sub.3−2x**Al.sub.1+2x**O.sub.4−4x**N.sub.4x**:Eu is interesting for very many applications. In particular, it is possible to provide phosphors which have peak wavelengths between those of the yellow-emitting Y.sub.3Al.sub.5O.sub.12:Ce, of the orange-red-emitting (Ca,Sr,Ba).sub.2Si.sub.5N.sub.8:Eu and of the red-emitting (Sr,Ca)SiAlN.sub.3:Eu.
(166) FIG. 158 shows crystallographic data of single crystals of the phosphors AB12-1 and AB12-2 of the phosphor according to the present disclosure having the molecular formulae SrLi.sub.3−2x**Al.sub.1+2x**O.sub.4−4x**N.sub.4x**:Eu.sup.2+ where x**=0.125 (AB12-1) and x**=0.1375 (AB12-2).
(167) FIG. 159 shows atomic positions in the structure of SrLi.sub.3−2x**Al.sub.1+2x**O.sub.4−4x**N.sub.4x**:Eu.sup.2+ for AB12-2.
(168) FIG. 161 illustrates the emission spectrum of AB17 of the phosphor according to the present disclosure having the molecular formula Na.sub.0.125K.sub.0.87Li.sub.3SiO.sub.4:Eu. For measuring the emission spectrum, a single crystal of the phosphor according to the present disclosure was excited with a primary radiation having a wavelength of 460 nm. The curves designated by Peak1 and Peak2 represent two Gaussian curves for describing the total emission with two emission peaks. The measured curve is congruent with the sum of the two Gaussian curves as calculated curve. The wavelength of the emission peak having the highest intensity is referred to as peak wavelength. The wavelength of the emission peak having lower intensity is referred to as relative emission maximum. The data resulting from the spectrum are summarized in FIG. 162.
(169) FIG. 163 shows the emission spectrum of three embodiments of the phosphor according to the present disclosure (Na.sub.rK.sub.1−r).sub.1Li.sub.3SiO.sub.4:Eu where 0.05<r<0.2 with different proportions r. These also exhibit a wide emission.
(170) FIG. 164 shows an overview of simulated optical data of conversion LEDs. A blue-emitting semiconductor chip based on InGaN is used as primary radiation source; the peak wavelength of the primary radiation is 438 nm or 443 nm. The phosphors used for converting the primary radiation are AB17 and (Lu, Y).sub.3Al.sub.5O.sub.12:Ce. The comparative examples are identified by Comp1, Comp2 and Comp3 and the embodiments according to the present disclosure by AB17-LED1 and AB17-LED2. For all the conversion LEDs, the overall radiation of the conversion LEDs results from a superimposition of the primary and secondary radiations. The color loci of the overall radiation all lie in the cold-white range with color temperatures of more than 8000 K close to the locus of the Planckian radiator. Surprisingly, the embodiments according to the present disclosure have a high color rendering index where CRI>80 and R9>50, while the comparative examples only have a CRI<70 and R9<0. This is attributable to the wide emission of the phosphor AB17 from the green to the red spectral range. The phosphor (Na.sub.rK.sub.1−r).sub.1(TA).sub.3(TD).sub.1(XB).sub.4:Eu where 0.05<r<0.2, in particular (Na.sub.rK.sub.1−r).sub.1Li.sub.3SiO.sub.4:Eu, is thus suitable in particular for conversion LEDs for general lighting. The phosphor can advantageously be used as sole phosphor in a conversion LED for general lighting.
(171) FIG. 165 illustrates the color loci of the overall radiation of the conversion LEDs from FIG. 164. As is evident, the color loci are all situated close to the color loci of the Planckian radiator.
(172) FIG. 166 illustrates emission spectra of the conversion LEDs AB17-LED2 and Comp2 from FIG. 164.
(173) FIG. 167 shows an overview of simulated optical data of conversion LEDs. A blue-emitting semiconductor chip based on InGaN is used as primary radiation source; the peak wavelength is 443 nm, 446 nm or 433 nm. The phosphors used for converting the primary radiation are AB17 and Lu.sub.3Al.sub.5O.sub.12:Ce. The comparative examples are identified by Comp4 and Comp5 and the embodiments according to the present disclosure are identified by AB17-LED3, AB17-LED4 and AB17-LED5. In the embodiments according to the i present disclosure invention, only AB17 is used as phosphor, while in the comparative examples, a second, red-emitting phosphor CaAlSiN.sub.3:Eu is used alongside Lu.sub.3Al.sub.5O.sub.12:Ce. Surprisingly, the overall radiation of the embodiments according to the present disclosure has a very large overlap with the transmission range of standard filters and filters for larger color spaces (HCG, High Color Gamut), such that only little light is lost and the achievable color space is as large as possible. As is evident, with the embodiments according to the present disclosure having only one phosphor, it is possible to obtain a high, in some instances greater coverage of the colors of the sRBG color space than with the comparative examples in which two phosphors are used. The phosphor (Na.sub.rK.sub.1−r).sub.1(TA).sub.3(TD).sub.1(XB).sub.4:Eu where 0.05<r≤0.2, in particular (Na.sub.rK.sub.1−r).sub.1Li.sub.3SiO.sub.4:Eu, is thus suitable in particular for conversion LEDs for backlighting applications. The phosphor can advantageously be used as sole phosphor in a conversion LED for backlighting applications.
(174) FIG. 168 illustrates emission spectra of the conversion LEDs AB17-LED5 and Comp5 from FIG. 167.
(175) FIGS. 169 and 170 show the spanned color spaces of the filtered overall radiation of various conversion LEDs from FIG. 167 and the overlap thereof with the sRGB color space. It is evident that a large bandwidth of colors can be rendered with the exemplary embodiments AB17-LED3 and AB17-LED5; primarily in the green corner of the spanned color triangle it is possible to attain more colors than with the exemplary embodiments.
(176) FIG. 171 shows a unit cell of the tetragonal crystal structure of the phosphor Na.sub.0.125K.sub.0.87Li.sub.3SiO.sub.4:Eu (AB17) in a schematic illustration along the crystallographic c-axis. The closely hatched circles represent Na atoms and the white circles represent K atoms. The hatched regions represent LiO.sub.4 tetrahedra, and the closely hatched regions represent SiO.sub.4 tetrahedra. The LiO.sub.4 and SiO.sub.4 tetrahedra are corner- and edge-linked and form channels in which the Na and K atoms are arranged. The crystal structure is related to the crystal structure of AB3, AB7, AB8, AB9, AB13, AB14, AB15 and AB16.
(177) In particular, two types of channels are contained in the crystal structure. Exclusively K atoms are arranged in the first channels, while Na and K atoms are arranged in the other channels. SiO.sub.4 tetrahedra (closely hatched) are arranged in the form of a helix (FIG. 172) around the channels in which exclusively K atoms are arranged. The Na atoms (closely hatched circles), within the channels in which Na and K atoms are arranged, are surrounded by SiO.sub.4 tetrahedra in distorted tetrahedral fashion (black regions; FIG. 173). FIG. 172 shows the channel containing only K atoms. FIG. 173 shows the channel containing K atoms and Na atoms. The sequence of the arrangement of the K atoms and Na atoms within the channel is NaKKKNaKKK. The illustrations of the excerpts from the crystal structure in FIGS. 172 and 173 are perpendicular to the crystallographic c-axis.
(178) FIG. 174 shows crystallographic data of Na.sub.0.125K.sub.0.875Li.sub.3SiO.sub.4:Eu (AB17).
(179) FIG. 175 shows atomic positions in the structure of Na.sub.0.125K.sub.0.875Li.sub.3SiO.sub.4:Eu (AB17).
(180) FIG. 176 shows anisotropic displacement parameters of Na.sub.0.125K.sub.0.875Li.sub.3SiO.sub.4:Eu (AB17).
(181) FIG. 177 shows a crystallographic evaluation of the X-ray powder diffractogram of the seventeenth exemplary embodiment AB17. The diagram illustrates a comparison of the measured reflections with the calculated reflections for Na.sub.0.125K.sub.0.875Li.sub.3SiO.sub.4:Eu. The upper part of the diagram shows the experimentally observed reflections (Mo K.sub.α1 radiation); the lower part of the diagram shows the calculated reflection positions. The calculation was made on the basis of the structure model for Na.sub.0.125K.sub.0.875Li.sub.3SiO.sub.4:Eu, as described in FIGS. 171-176. Reflections of secondary phases are identified by *. The correspondence of the reflections of the calculated powder diffractogram to the reflections of the measured powder diffractogram reveals a correspondence of the crystal structure of single crystals and powders of the phosphor.
(182) The present disclosure is not restricted to the exemplary embodiments by the description on the basis of said exemplary embodiments. Rather, the present disclosure encompasses any novel feature and also any combination of features, which in particular includes any combination of features in the patent claims, even if this feature or this combination itself is not explicitly specified in the patent claims or exemplary embodiments.
(183) While the disclosed embodiments have been particularly shown and described with reference to specific embodiments, it should be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the disclosed embodiments as defined by the appended claims. The scope of the disclosed embodiments is thus indicated by the appended claims and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced.
(184) The following exemplary embodiments pertain to further aspects of this disclosure:
(185) Embodiment 1 is a phosphor having the general molecular formula (MA).sub.a(MB).sub.b(MC).sub.c(MD).sub.d(TA).sub.e(TB).sub.f(TC).sub.g(TD).sub.h(TE).sub.i(TF).sub.j(XA).sub.k(XB).sub.l(XC).sub.m(XD).sub.n:E,
(186) wherein
(187) MA is selected from a group of monovalent metals which comprises Li, Na, K, Rb, Cs, Cu, Ag and combinations thereof, MB is selected from a group of divalent metals which comprises Mg, Ca, Sr, Ba, Zn, Mn, Eu, Yb, Ni, Fe, Co and combinations thereof, MC is selected from a group of trivalent metals which comprises Y, Fe, Cr, Sc, In, rare earth metals and combinations thereof, MD is selected from a group of tetravalent metals which comprises Zr, Hf, Mn, Ce and combinations thereof, TA is selected from a group of monovalent metals which comprises Li, Na, Cu, Ag and combinations thereof, TB is selected from a group of divalent metals which comprises Mg, Zn, Mn, Eu, Yb, Ni and combinations thereof, TC is selected from a group of trivalent metals which comprises B, Al, Ga, In, Y, Fe, Cr, Sc, rare earth metals and combinations thereof, TD is selected from a group of tetravalent metals which comprises Si, Ge, Sn, Mn, Ti, Zr, Hf, Ce and combinations thereof, TE is selected from a group of pentavalent elements which comprises P, Ta, Nb, V and combinations thereof, TF is selected from a group of hexavalent elements which comprises W, Mo and combinations thereof, XA is selected from a group of elements which comprises F, Cl, Br and combinations thereof, XB is selected from a group of elements which comprises O, S and combinations thereof,
XC=N
XD=C
E=Eu,Ce,Yb and/or Mn,
a+b+c+d=t
e+f+g+h+i+j=u
k+l+m+n=v
a+2b+3c+4d+e+2f+3g+4h+5i+6j−k−2l−3m−4n=w
0.8≤t≤1
3.5≤u≤4
3.5≤v≤4
(−0.2)≤w≤0.2 and
0≤m<0.875 v and/or v≥l>0.125 v.
(188) Embodiment 2 is the phosphor according to embodiment 1, which has a crystal structure in which TA, TB, TC, TD, TE and/or TF are surrounded by XA, XB, XC and/or XD and the resultant structural units are linked via common corners and edges to form a three-dimensional spatial network having cavities or channels and MA, MB, MC and/or MD are/is arranged in the cavities or channels.
(189) Embodiment 3 is the phosphor according to embodiments 1 or 2 claims, wherein
a+b+c+d=1
e+f+g+h+i+j=4
k+l+m+n=4
a+2b+3c+4d+e+2f+3g+4h+5i+6j−k−2l−3m−4n=0 and
m<3.5.
(190) Embodiment 4 is the phosphor according to any of embodiments 1 to 3, which has the following general molecular formula: (MA).sub.a(MB).sub.b(TA).sub.e(TB).sub.f(TC).sub.g(TD).sub.h(XB).sub.l(XC).sub.m:E,
(191) wherein
(192) MA is selected from a group of monovalent metals which comprises Li, Na, K, Rb, Cs, Cu, Ag and combinations thereof, MB is selected from a group of divalent metals which comprises Mg, Ca, Sr, Ba, Zn, Mn, Eu, Yb, Ni, Fe, Co and combinations thereof, TA is selected from a group of monovalent metals which comprises Li, Na, Cu, Ag and combinations thereof, TB is selected from a group of divalent metals which comprises Mg, Zn, Mn, Eu, Yb, Ni and combinations thereof, TC is selected from a group of trivalent metals which comprises B, Al, Ga, In, Y, Fe, Cr, Sc, rare earths and combinations thereof, TD is selected from a group of tetravalent metals which comprises Si, Ge, Sn, Mn, Ti, Zr, Hf, Ce and combinations thereof, XB is selected from a group of elements which comprises O, S and combinations thereof,
XC=N
E=Eu,Ce,Yb and/or Mn,
a+b=1
e+f+g+h=4
l+m=4
a+2b+e+2f+3g+4h−2l−3m=0
and
0≤m<3.5.
(193) Embodiment 5 is the phosphor according to embodiment 4, wherein MA is selected from a group of monovalent metals which comprises Li, Na, K, Rb, Cs and combinations thereof, MB is selected from a group of divalent metals which comprises Mg, Ca, Sr, Ba, Eu and combinations thereof, TA is selected from a group of monovalent metals which comprises Li, Na, Cu, Ag and combinations thereof, TB is selected from a group of divalent metals which comprises Eu, TC is selected from a group of trivalent metals which comprises B, Al, Ga, In and combinations thereof, TD is selected from a group of tetravalent metals which comprises Si, Ge, Sn, Mn, Ti and combinations thereof,
XB=O.
(194) Embodiment 6 is the phosphor according to any of embodiments 4 to 5, wherein f=g=0.
(195) Embodiment 7 is the phosphor according to any of embodiments 1 to 5, which has one of the following general molecular formulae:
(MA).sub.1(TA).sub.3(TD).sub.1(KB).sub.4:E,
(MA).sub.1(TA).sub.3−x(TD).sub.1−x(TB).sub.x(TC).sub.x(XB).sub.4:E,
(MA).sub.1−x′(MB).sub.x′(TA).sub.3(TD).sub.1−x′(TC).sub.x′(XB).sub.4:E,
(MA).sub.1−x″(MB).sub.x″(TA).sub.3−x″(TD).sub.1−x″(TB).sub.2x″(XB).sub.4:E,
(MA).sub.1(TA).sub.3−2z(TB).sub.3z(TD).sub.1−z(XB).sub.4:E or
(MA).sub.1(TA).sub.3(TD).sub.1−2z′(TC).sub.z′(TE).sub.z′(XB).sub.4:E, wherein
0≤x≤1,
0≤x′≤1,
0≤x″≤1,
0≤z≤1,
0≤z′≤0.5
and E is selected from a group which comprises Eu, Ce, Yb, Mn and combinations thereof.
(196) Embodiment 8 is the phosphor according to any of embodiments 1 to 5, which has one of the following general molecular formulae:
(MA).sub.1−y(TB).sub.y(TA).sub.3−2y(TC).sub.3y(TD).sub.1−y(XB).sub.4−4y(XC).sub.4y:E,
(MA).sub.1−y*(MB).sub.y*(TA).sub.3−2y*(TC).sub.3y*(TD).sub.1−y*(XB).sub.4−4y*(XC).sub.4y*:E,
(MA).sub.1(TA).sub.3−y′(TC).sub.y′(TD).sub.1(XB).sub.4−2y′(XC).sub.2y′:E,
(MA).sub.1(TA).sub.3−y″(TB).sub.y″(TD).sub.1(XB).sub.4−y″(XC).sub.y″:E,
(MA).sub.1−w′″(MB).sub.w′″(TA).sub.3(TD).sub.1(XB).sub.4−w′″(XC).sub.w′″:E,
(MA).sub.1(TA).sub.3−w′(TC).sub.2w′(TD).sub.1−w′(XB).sub.4−w′(XC).sub.w′:E or
(MA).sub.1−w″(MB).sub.w″(TA).sub.3−w″(TD).sub.1−w″(TC).sub.2w″(XB).sub.4−2w″(XC).sub.2w″:E,
wherein
0≤y<0.875,
0<y*≤0.875,
0≤y′<1.75,
0≤y″≤3,
0≤w′″≤1,
0≤w′≤1,
0≤w″≤1
and E is selected from a group which comprises Eu, Ce, Yb, Mn and combinations thereof.
(197) Embodiment 9 is the phosphor according to embodiment 7, which has one of the following general molecular formulae:
(MA)Li.sub.3−xSi.sub.1−xZn.sub.xAl.sub.xO.sub.4:E
(MA)Li.sub.3−xSi.sub.1−xMg.sub.xAl.sub.xO.sub.4:E
(MA).sub.1−x′Ca.sub.x′Li.sub.3Si.sub.1−x′Al.sub.x′O.sub.4:E
(MA).sub.1−x″Ca.sub.x″Li.sub.3−x″Si.sub.1−x″Mg.sub.2x″O.sub.4:E
(MA)Li.sub.3−2zMg.sub.3zSi.sub.1−zO.sub.4:E or
(MA)Li.sub.3Si.sub.1−2z′Al.sub.z′P.sub.z′O.sub.4:E, wherein
0≤x≤1,
0≤x′≤1,
0≤x″≤1,
0≤z≤1,
0≤z′≤0.5 and E is selected from a group which comprises Eu, Ce, Yb, Mn and combinations thereof.
(198) Embodiment 10 is the phosphor according to embodiment 8, which has one of the following general molecular formulae:
(MA).sub.1−yZn.sub.yLi.sub.3−2yAl.sub.3ySi.sub.1−yO.sub.4−4yN.sub.4y:E,
(MA).sub.1−y*Ca.sub.y*Li.sub.3−2y*Al.sub.3y*Si.sub.1−y*O.sub.4−4y*N.sub.4y*:E,
(MA).sub.1−y***Sr.sub.y***Li.sub.3−2y*Al.sub.3y***Si.sub.1−y***O.sub.4−4y***N.sub.4y***:E
(MA).sub.1−y**Eu.sub.y**Li.sub.3−2Al.sub.3y**Si.sub.1−y**O.sub.4−4y**N.sub.4y**:E
(MA)Li.sub.3−y′Al.sub.y′SiO.sub.4−2y′N.sub.2y′:E,
(MA)Li.sub.3−y″Mg.sub.y″SiO.sub.4−y″N.sub.y″:E,
(MA).sub.1−w′″Ca.sub.w′″Li.sub.3SiO.sub.4−w′″N.sub.w′″:E,
(MA)Li.sub.3−w′Al.sub.2w′Si.sub.1−w′O.sub.4−w′N.sub.w′:E,
(MA).sub.1−w″Ca.sub.w″Li.sub.3−w″Si.sub.1−w″Al.sub.2w″O.sub.4−2w″N.sub.2w″:E,
wherein
0<y*<0.875,
0<y**<0.875,
0<y***<0.875,
0≤y<0.875,
0≤y′≤1.75,
0≤y″≤3,
0≤w′″≤1,
0≤w′≤1,
0≤w″≤1 and E is selected from a group which comprises Eu, Ce, Yb, Mn and combinations thereof.
(199) Embodiment 11 is the phosphor according to embodiment 7, which has one of the following general molecular formulae:
(200) (Na.sub.rK.sub.1−r).sub.1(TA).sub.3(TD).sub.1(XB).sub.4:E, (Rb.sub.r′Li.sub.1−r′).sub.1(TA).sub.3(TD).sub.1(XB).sub.4:E, (K.sub.1−r″−′″Na.sub.r″Li.sub.r′″).sub.1(TA).sub.3(TD).sub.1(XB).sub.4:E, (Cs,Na,K,Li).sub.1(TA).sub.3(TD).sub.1(XB).sub.4:E or (Rb.sub.r*Na.sub.1−r*).sub.1(TA).sub.3(TD).sub.1(XB).sub.4:E, (Cs,Na,Rb,Li).sub.1(TA).sub.3(TD).sub.1(XB).sub.4:E, (Cs,Na,K).sub.1(TA).sub.3(TD).sub.1(XB).sub.4:E or (Rb,Na,K).sub.1(TA).sub.3(TD).sub.1(XB).sub.4:E,
wherein
0≤r≤1,
0≤r′≤1,
0<r″≤0.5,
0<r′″<0.5,
0<r*<1
and E is selected from a group which comprises Eu, Ce, Yb, Mn and combinations thereof.
(201) Embodiment 12 is the phosphor according to embodiment 11, which has one of the following general molecular formulae: (Na.sub.rK.sub.1−r)Li.sub.3SiO.sub.4:E, (Rb.sub.r′Li.sub.1−r′)Li.sub.3SiO.sub.4:E, (K.sub.1−r″−r′″Na.sub.r″Li.sub.r′″)Li.sub.3SiO.sub.4:E, (Cs,Na,K,Li)Li.sub.3SiO.sub.4:E, (Rb.sub.r*Na.sub.1−r*).sub.1Li.sub.3SiO.sub.4:E, (Cs,Na,Rb,Li).sub.1Li.sub.3SiO.sub.4:E, (Cs,Na,K)Li.sub.3SiO.sub.4:E or (Rb,Na,K)Li.sub.3SiO.sub.4:E
(202) wherein
0≤r≤1,
0≤r′≤1,
0<r′″<0.5,
0<r′″<0.5,
0<r*<1
and E is selected from a group which comprises Eu, Ce, Yb, Mn and combinations thereof.
(203) Embodiment 13 is the phosphor according to embodiment 10, which has the formula Na.sub.1−y*Ca.sub.y Li.sub.3−2y*Al.sub.3y*Si.sub.1−y*O.sub.4−4y*N.sub.4y*:E, wherein 0<y*<0.875, preferably 0<y*≤0.5, and E is selected from a group which comprises Eu, Mn, Ce, Yb and combinations thereof.
(204) Embodiment 14 is the phosphor according to embodiment 10, which has the formula Na.sub.1−y**Eu.sub.y**Li.sub.3−2y**Al.sub.3y**Si.sub.1−y**O.sub.4−4y**N.sub.4y**:E, wherein 0<y**<0.875, preferably 0<y**<0.5, and E is selected from a group which comprises Eu, Mn, Ce, Yb and combinations thereof.
(205) Embodiment 15 is the phosphor according to any of embodiments 1 to 5, which has the formula (MB)Li.sub.3−2x**Al.sub.1+2x**O.sub.4−4x**N.sub.4**:E, wherein
(206) 0<x**<0.875, MB is selected from a group of divalent metals which comprises Mg, Ca, Sr, Ba, Zn and combinations thereof, and E is selected from a group which comprises Eu, Mn, Ce, Yb and combinations thereof.
(207) Embodiment 16 is the phosphor according to any of embodiments 1 to 5, which has the formula (MB)(Si.sub.0.25Al.sub.−1/8+r**/2Li.sub.7/8−r**/2).sub.4(O.sub.1−r**N.sub.r**).sub.4:E, wherein 0.25≤r**≤1, MB is selected from a group of divalent metals which comprises Mg, Ca, Sr, Ba and combinations thereof, and E=Eu, Ce, Yb and/or Mn.
(208) Embodiment 17 is a method for producing the phosphor according to any of embodiments 1 to 16 including the following method steps:
(209) A) mixing starting materials of the phosphor,
(210) B) heating the mixture obtained under A) to a temperature T1 of between 500 and 1400° C.,
(211) C) annealing the mixture at a temperature T1 of 500 to 1400° C. for 0.5 minute to ten hours.
LIST OF REFERENCE SIGNS
(212) ppm Parts per million λpeak Peak wavelength λ.sub.dom Dominant wavelength AB Exemplary embodiment g Gram E Emission mmol Millimol Mol % Mol percent R.sub.inf Diffuse reflection lm Lumen W Watt LER Luminous efficiency LED Light-emitting diode CRI Color rendering index CCT Correlated color temperature R9 Color rendering index K/S Kubelka-Munk function K Kelvin cm Centimeter nm Nanometer ° 2θ Degree 2 Theta I, II, III, IV, V, VI X-ray powder diffractogram Ew White point KL Conversion line T Temperature ° C. Degree Celsius
