Abstract
A luminophore having the empirical formula A.sub.3M*O.sub.xF.sub.9−2x:Mn.sup.4+ where A may be or include Li, Na, Rb, K, Cs, or combinations thereof. M* may be or include Cr, Mo, W, or combinations thereof. x may be or include 0<x<4.5.
Claims
1. (canceled)
2. A luminophore having the empirical formula A.sub.3M*O.sub.xF.sub.9−2x:Mn.sup.4+, wherein: A is selected from the group consisting of Li, Na, Rb, K, Cs, or combinations thereof, M* is selected from the group consisting of Cr, Mo, W, or combinations thereof and 0<x<4.5.
3. The luminophore as claimed in claim 2, where x=1, x=2, x=3, or x=4.
4. The luminophore as claimed in claim 2, having the empirical formula (K.sub.1−zA*.sub.z).sub.3M*O.sub.xF.sub.9−2x:Mn.sup.4+, wherein: A* is selected from the group consisting of Li, Na, Rb, Cs, or combinations thereof, M* is selected from the group consisting of Cr, Mo, W, or combinations thereof; 0≤z≤1, and x=1, x=2, x=3, or x=4.
5. The luminophore as claimed in claim 2, having the empirical formula K.sub.3M*O.sub.xF.sub.9−2x:Mn.sup.4+; wherein: M* is selected from the group consisting of Cr, Mo, W, or combinations thereof: and x=1, x=2, x=3, or x=4.
6. The luminophore as claimed in claim 2, having the empirical formula K.sub.3M*OF.sub.7:Mn.sup.4+, wherein: M* is selected from the group consisting of Cr, Mo, W, or combinations thereof.
7. (canceled)
8. The luminophore having the empirical formula: A.sub.3MO.sub.xF.sub.8−2x:Mn.sup.4+; wherein: A is selected from the group consisting of Li, Na, Rb, K, Cs, or combinations thereof; M is selected from the group consisting of V, Nb, or combinations thereof; and 1<x<4.
9. The luminophore as claimed in claim 8, wherein x=2 or x=3.
10. The luminophore as claimed in claim 9 having the empirical formula (K.sub.1−zA*.sub.z).sub.3MO.sub.xF.sub.8−2x:Mn.sup.4+; wherein: A* is selected from the group consisting of Li, Rb, Na, Cs, or combinations thereof, M is selected from the group consisting of V, Nb, or combinations thereof: 0≤z≤1, and x=2 or x=3.
11. The luminophore as claimed in claim 10 having the empirical formula (K.sub.1−zNA.sub.z).sub.3MO.sub.xF.sub.8−2x:Mn.sup.4+; wherein: M is selected from the group consisting of V, Nb, or combinations thereof 0≤z≤⅔; and x=2 or x=3.
12. The luminophore as claimed in claim 11 having the empirical formula (K.sub.1−zNa.sub.z).sub.3MO.sub.2F.sub.4:Mn.sup.4+; wherein: M is selected from the group consisting of V, Nb, or combinations thereof: and 0<z≤⅔.
13. A conversion LED comprising a luminophore as claimed in claim 2.
14. The conversion LED as claimed in claim 13, further comprising: a semiconductor layer sequence configured to emit electromagnetic primary radiation; and a conversion element that comprises the luminophore and configured to at least partially convert the electromagnetic primary radiation to electromagnetic secondary radiation.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0114] Further advantageous embodiments and developments will be apparent from the working examples described hereinafter in conjunction with the figures. Identical, similar or equivalently functioning elements are labelled with the same reference signs in the figures. The figures and the relative proportions of the elements represented in the figures are not to be considered to be true to scale. Instead, individual elements may be shown exaggerated in size for ease of visualization and/or better understanding.
[0115] FIG. 1A shows a unit cell with adjoining polyhedra of the first working example K.sub.3MoOF.sub.7:Mn.sup.4+ (WE1) of the luminophore (space group No. 2; P-1).
[0116] FIG. 1B shows a unit cell of cubic K.sub.2SiF.sub.6:Mn.sup.4+ (space group No. 225; Fm-3m).
[0117] FIG. 2 shows an emission spectrum of WE1 (powder sample) on excitation with blue primary radiation (λ.sub.exc=460 nm).
[0118] FIG. 3 shows the excitation spectrum of WE1 based on the emission maximum at 627 nm.
[0119] FIG. 4 shows a Rietveld refinement of a powder sample of K.sub.3MoOF.sub.7:Mn.sup.4+ (WE1).
[0120] FIG. 5 shows a PXRD comparison (Mo—K.sub.α1 radiation) of K.sub.3MoOF.sub.7 and K.sub.3MoOF.sub.7:Mn.sup.4+ (WE1).
[0121] FIG. 6 shows a unit cell of the second working example K.sub.3WOF.sub.7:Mn.sup.4+ (WE2) of the luminophore (space group No. 14; P2.sub.1/c).
[0122] FIG. 7 shows an emission spectrum of WE2 (powder sample) on excitation with blue primary radiation (λ.sub.exc=460 nm).
[0123] FIG. 8 shows the excitation spectrum of WE2 based on the emission maximum at 627 nm.
[0124] FIG. 9 shows a comparison of powder x-ray diffractograms (PXRD) (Mo—Kα.sub.1 radiation) of K.sub.3WOF.sub.7:Mn.sup.4+ from experiment and simulation.
[0125] FIG. 10 shows a PXRD comparison (Mo—K.sub.α1 radiation) of K.sub.3MoOF.sub.7 and K.sub.3MoOF.sub.7:Mn.sup.4+.
[0126] FIG. 11 shows the thermal characteristics of various luminophores in comparison.
[0127] FIG. 12 shows a unit cell of the third working example K.sub.2NaNbO.sub.2F.sub.4:Mn.sup.4+ (WE3) of the luminophore (space group No. 225; Fm-3m).
[0128] FIG. 13 shows an emission spectrum of WE3 (powder sample and single grain) on excitation with blue primary radiation.
[0129] FIG. 14 shows the excitation spectrum of WE3 based on the emission maximum at 632 nm.
[0130] FIG. 15 shows a comparison of powder x-ray diffractograms (PXRD) (Mo—Kα.sub.1 radiation) of K.sub.2NaNbO.sub.2F.sub.4:Mn.sup.4+ from experiment and simulation.
[0131] FIG. 16 shows a PXRD comparison (Mo—K.sub.α1 radiation) of K.sub.2NaNbO.sub.2 F.sub.4 and K.sub.2NaNbO.sub.2F.sub.4:Mn.sup.4+
DETAILED DESCRIPTION
[0132] FIG. 1A shows a unit cell with adjoining polyhedra of K.sub.3MoOF.sub.7:Mn.sup.4+ along [−100]. K.sub.3MoOF.sub.7:Mn.sup.4+, by comparison with K.sub.2SiF.sub.6:Mn.sup.4+, surprisingly crystallizes in a new, unknown structure type in the P-1 space group (No. 2); the unit cell shows a triclinic metric with lattice parameters a=6.7602(4), b=8.1443(5), c=8.3106(5) Å and α=115.242(2), β=90.582(2), γ=92.732(2)° (volume=413.16(4) Å.sup.3). The crystallographic data are summarized in tables 1-3. Mo has partly been replaced by Mn.sup.4+ (not shown).
[0133] FIG. 1B shows the unit cell of the crystal structure of K.sub.2SiF.sub.6:Mn.sup.4+, which crystallizes in the cubic space group Fm-3m. The K atoms are shown as unfilled ellipsoids, the F atoms as filled circles, and SiF.sub.6 octahedra with Si in the center and F shaded at the vertices. Si has been partly replaced by Mn (not shown). K.sub.2SiF.sub.6:Mn.sup.4+ crystallizes in the K.sub.2PtCl.sub.6 type in the Fm-3m space group (No. 225). The unit cell shows a cubic metric with a lattice parameter a=8.134(1) Å.
[0134] A comparison of FIGS. 1A and 1B shows that the two structures differ significantly from one another. In cubic K.sub.2SiF.sub.6:Mn.sup.4+ there are exclusively SiF.sub.6 octahedra formed from F anions, and in K.sub.3MoOF.sub.7:Mn.sup.4+ there are MoOF.sub.5 octahedra formed from O and F anions. By virtue of the arrangement of the O/F atoms, the Mo atom is deflected in each case from the middle of the octahedron in the direction of the O atom (higher covalence of the Mo—O bond than of the Mo—F bond, not shown in the figure). The position and orientation of the respective octahedra in relation to the unit cell are likewise distinctly different from one another in the two structures.
[0135] FIG. 2 shows an emission spectrum of a powder sample of WE1 on excitation with blue primary radiation (λ.sub.exc=460 nm). The x axis shows the wavelength in nanometers, and the y axis the relative intensity in percent. The emission maximum is at 627 nm.
[0136] FIG. 3 shows the excitation spectrum of WE1 based on the emission maximum at 627 nm. The x axis shows the wavelength in nanometers, and the y axis the relative spectral absorption in percent.
[0137] FIG. 4 shows a Rietveld refinement of a powder sample of K.sub.3MoOF.sub.7:Mn.sup.4+. The measured curve is represented by the bold curve. The simulation is shown as a light-colored line above the measurement curve. In addition, as well as the difference curve, the reflection positions of K.sub.3MoOF.sub.7:Mn.sup.4+ and the KHF.sub.2 present in the luminophore composition are shown.
[0138] FIG. 5 shows a PXRD comparison (Mo—K.sub.α1 radiation) of undoped K.sub.3MoOF.sub.7 before the ball milling process (intermediate in the synthesis of WE1) with the experimental PXRD of K.sub.3MoOF.sub.7:Mn.sup.4+after the ball milling process. Good agreement is apparent, and so these studies by means of x-ray diffraction show that the structure of K.sub.3MoOF.sub.7 is conserved by the ball milling process in the case of K.sub.3MoOF.sub.7:Mn.sup.4+ too.
[0139] FIG. 6 shows a unit cell of K.sub.3WOF.sub.7:Mn.sup.4+ along [−100]. K.sub.3WOF.sub.7:Mn.sup.4+, by comparison with K.sub.2SiF.sub.6:Mn.sup.4+, surprisingly crystallizes in a new, unknown structure type in the P 21/c space group (No. 14). The unit cell shows monoclinic metric with lattice parameters a=8.8415(4), b=13.7986(6), c=6.7970(3) Å and β=93.0410(10)° (volume=828.07(6) Å.sup.3). The crystallographic data are summarized in tables 5 to 7. W has been partly replaced by Mn.sup.4+ (not shown).
[0140] A comparison of FIGS. 6 and 1B shows that the structures of K.sub.3WOF.sub.7:Mn.sup.4+ and K.sub.2SiF.sub.6:Mn.sup.4+ differ significantly. In cubic K.sub.2SiF.sub.6:Mn.sup.4+ there are exclusively SiF.sub.6 octahedra formed from F anions, and in K.sub.3WOF.sub.7:Mn there are WOF.sub.5 octahedra formed from O and F anions. The ordering of the O/F atoms (with occupation in each case of half of 2 of the 6 octahedral vertices with O and F), the W atom is deflected in each case from the middle of the octahedron in the direction of the mixedly occupied O/F positions (higher covalence of the W—O bond than of the W—F bond, not shown in the figure). The position and orientation of the respective octahedra in relation to the unit cell are likewise distinctly different from one another in the two structures.
[0141] FIG. 7 shows an emission spectrum of a powder sample of WE2 on excitation with blue primary radiation (λ.sub.exc=460 nm). The emission maximum is at 627 nm.
[0142] FIG. 8 shows the excitation spectrum of WE2 based on the emission maximum at 627 nm.
[0143] FIG. 9 shows a comparison of powder x-ray diffractograms (PXRD) (Mo—Kα.sub.1 radiation). What is shown is the x-ray diffractogram measured for the second working example WE2 of the inventive luminophore K.sub.3WOF.sub.7:Mn.sup.4+ compared to a simulation based on single-crystal x-ray diffraction data. Good agreement is apparent, and so these studies by means of x-ray powder methods show that the luminophore K.sub.3WOF.sub.7:Mn.sup.4+ was preparable in good quality.
[0144] FIG. 10 shows a PXRD comparison (Mo—K.sub.α1 radiation) of undoped K.sub.3MoOF.sub.7 before the ball milling process (intermediate in the synthesis of WE2) with the experimental PXRD of K.sub.3WOF.sub.7:Mn.sup.4+ after the ball milling process. Good agreement is apparent, and so these studies by means of x-ray diffraction show that the structure of K.sub.3WOF.sub.7 is conserved by the ball milling process in the case of K.sub.3WOF.sub.7:Mn.sup.4+ too.
[0145] FIG. 11 shows the progression of integral intensity I against the temperature of the luminophores K.sub.2SiF.sub.6:Mn.sup.4+, K.sub.3WOF.sub.7:Mn.sup.4+ and CaAl.sub.12O.sub.19:Mn.sup.4+. The slow decay time of the Mn.sup.4+ atom, i.e. the slow transition from the excited state to the ground state, which is within the ms range, limits solutions with such luminophores essentially to “low-power” applications (few blue photons/time and area). Otherwise, saturation of the excited state sets in and any further incident blue photon does not trigger a conversion process, such that the overall efficiency of the LED then falls significantly. In such cases, the LED chips, i.e. the semiconductor layer sequences, typically reach temperatures well below 100° C., in view of which a decrease in intensity of only 13% for K.sub.3WOF.sub.7:Mn at 75° C. constitutes a surprisingly good value. CaAl.sub.12O.sub.19:Mn.sup.4+ shows that the temperature characteristics of oxidic luminophores are much poorer than those of the corresponding fluoridic luminophores. The data for K.sub.2SiF.sub.6:Mn.sup.4+ are known from the literature [Temperature dependence of photoluminescence spectra and dynamics of the red-emitting K.sub.2SiF.sub.6:Mn.sup.4+ phosphor, Journal of Alloys and Compounds 2017, Shao et al.]
[0146] FIG. 12 shows a unit cell of K.sub.2NaNbO.sub.2F.sub.4:Mn.sup.4+ along [−100]. K.sub.2NaNbO.sub.2F.sub.4:Mn.sup.4+ crystallizes in the perovskite structure class in the elpasolite structure type (K.sub.2NaAlF.sub.6) like K.sub.2SiF.sub.6:Mn.sup.4+ in the Fm-3m space group (No. 225). The unit cell thus also shows cubic metric with lattice parameter a=8.4726(4) Å (volume=608.21 Å.sup.3). The crystallographic data are summarized in tables 9 and 10.
[0147] A comparison of FIGS. 12 and 1B shows that the structures of K.sub.2NaNbO.sub.2F.sub.4:Mn.sup.4+ and K.sub.2SiF.sub.6:Mn.sup.4+ differ from one another. In cubic K.sub.2SiF.sub.6:Mn.sup.4+ there are exclusively SiF.sub.6 octahedra formed from F anions, and in K.sub.2NaNbO.sub.2F.sub.4:Mn.sup.4+ there are NbO.sub.2F.sub.4 octahedra formed from O and F anions.
[0148] FIG. 13 shows an emission spectrum of a powder sample and of a single grain of WE3 on excitation with blue primary radiation (λ.sub.exc=460 nm powder; (λ.sub.exc=448 nm single grain). The emission maximum of the powder sample is at 632 nm, and that of the single grain at 633 nm.
[0149] FIG. 14 shows the excitation spectrum of WE3 based on the emission maximum at 632 nm.
[0150] FIG. 15 shows a comparison of powder x-ray diffractograms (PXRD) (Mo—Kα.sub.1 radiation). What is shown is the x-ray diffractogram measured for the third working example WE3 of the inventive luminophore K.sub.2NaNbO.sub.2F.sub.4:Mn.sup.4+ compared to a simulation based on x-ray diffraction data. Good agreement is apparent, and so these studies by means of x-ray powder methods show that the luminophore K.sub.2NaNbO.sub.2F.sub.4:Mn.sup.4+ was preparable in good quality.
[0151] FIG. 16 shows a PXRD comparison (Mo—K.sub.α1 radiation) of undoped K.sub.2NaNbO.sub.2F.sub.4 before the ball milling process (intermediate in the synthesis of WE3) with the experimental PXRD of K.sub.2NaNbO.sub.2F.sub.4:Mn.sup.4+after the ball milling process. Good agreement is apparent, and so these studies by means of x-ray diffraction show that the structure of K.sub.2NaNbO.sub.2F.sub.4 is conserved by the ball milling process in the case of K.sub.2NaNbO.sub.2F.sub.4:Mn.sup.4+ too.
[0152] The working examples described in conjunction with the figures and the features thereof may also be combined with one another in further working examples, even if such combinations are not shown explicitly in the figures. In addition, the working examples described in conjunction with the figures may have additional or alternative features according to the general part of the description.
LIST OF REFERENCE SYMBOLS
[0153] A spectral absorption
[0154] WE working example
[0155] LED light-emitting diode
[0156] CRI color rendering index
[0157] LER luminous efficacy of radiation
[0158] CCT correlated color temperature
[0159] FWHM spectral width of emission, half-height width
[0160] ppm parts per million
[0161] VB comparative example
[0162] I intensity
[0163] mol % mole percent
[0164] nm nanometers
[0165] ° C. degrees Celsius
[0166] A.sub.exc excitation wavelength
[0167] A.sub.peak peak wavelength
[0168] A.sub.max emission maximum
[0169] A.sub.dom dominant wavelength
