LUMINOPHORE, METHOD FOR PRODUCTION THEREOF AND RADIATION-EMITTING COMPONENT

Abstract

A phosphor with the molecular formula EA.sub.3xRE.sub.xD.sub.2+yE.sub.12yN.sub.20zO.sub.z:M is specified, where EA is an element or a combination of elements from the group of divalent elements, RE is a rare earth element, D is an element or a combination of elements from the group of trivalent elements, E is an element or a combination of elements from the group of tetravalent elements, M is an activator element or a combination of activator elements, 0x3, 0y12 and z=yx, wherein z0. Further, a method for producing a phosphor and a radiation emitting component are specified.

Claims

1. A phosphor with a molecular formula EA.sub.3xRE.sub.xD.sub.2+yE.sub.12yN.sub.20zO.sub.z:M, wherein EA is an element or a combination of elements from the group of divalent elements, RE is a rare earth element, D is an element or a combination of elements from the group of trivalent elements, E is an element or a combination of elements from the group of tetravalent elements, M is an activator element or a combination of activator elements, and 0x3, 0y12 and z=yx, wherein z0.

2. The phosphor according to claim 1, wherein EA is an element or a combination of elements from the group formed by Ca, Sr and Ba, and/or D is an element or a combination of elements from the group formed by Al and Ga, and/or E is Si, and/or M is an element or a combination of elements from the group formed by Ce and Eu.

3. The phosphor according to claim 1, wherein the phosphor (1) comprises the molecular formula Ba.sub.3xLa.sub.xAl.sub.2+ySi.sub.12yN.sub.20zO.sub.z:Ce.sup.3+.

4. The Phosphor according to claim 1, wherein the phosphor, after excitation with electromagnetic radiation in the ultraviolet to blue wavelength range, emits electromagnetic radiation with an emission spectrum comprising an emission peak with an emission maximum in the cyan wavelength range.

5. The phosphor according to claim 1, wherein the emission peak comprises a full-width at half maximum in the region of between and including 80 nanometers and 110 nanometers.

6. The phosphor according to claim 1, wherein an electromagnetic radiation emitted by the phosphor comprises a dominant wavelength .sub.dom in the region of between and including 470 nanometers and 500 nanometers.

7. The phosphor according to claim 1, wherein a host lattice of the phosphor crystallizes in a trigonal space group.

8. The phosphor according to claim 1, wherein a crystal structure of the host lattice of the phosphor comprises layers with on all side corner-linked D(N,O).sub.4 tetrahedra and/or E(N,O).sub.4 tetrahedra.

9. A method for producing a phosphor with the molecular formula EA.sub.3xRE.sub.xD.sub.2+yE.sub.12yN.sub.20zO.sub.z:M, wherein EA is an element or a combination of elements from the group of divalent elements, RE is a rare earth element, D is an element or a combination of elements from the group of trivalent elements, E is an element or a combination of elements from the group of tetravalent elements, M is an activator element or a combination of activator elements, and 0<x3, 0y12 and z=yx, where z0, the method comprising: providing reactants, mixing the reactants to form a reactant mixture, and heating the reactant mixture.

10. A radiation emitting component comprising: a semiconductor chip which emits electromagnetic radiation of a first wavelength range during operation, and a conversion element with a phosphor according to claim 1, which converts electromagnetic radiation of the first wavelength range into electromagnetic radiation of a second wavelength range which is at least partially different from the first wavelength range.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Further advantageous embodiments, configurations and developments of the phosphor, the method for producing a phosphor and the radiation emitting component are shown in the following exemplary embodiments illustrated with the figures.

[0039] Elements that are identical, similar or have the same effect are marked with the same reference signs in the figures. The figures and the proportions of the elements shown in the figures are not to be regarded as true to scale. Rather, individual elements, in particular layer thicknesses, may be shown in exaggerated size for better visualization and/or understanding.

[0040] FIG. 11 shows a schematic representation of a phosphor according to an exemplary embodiment.

[0041] FIGS. 2 to 5 show schematic sections of a crystal structure of a host lattice of a phosphor according to an exemplary embodiment.

[0042] FIGS. 6 to 8 show emission spectra of a phosphor according to an exemplary embodiment and a phosphor according to a comparative example.

[0043] FIG. 9 schematically shows various steps of a method for producing a phosphor according to an exemplary embodiment.

[0044] FIG. 10 shows a radiation emitting component according to an exemplary embodiment.

DESCRIPTION

[0045] The phosphor 1 according to FIG. 1 has the molecular formula EA.sub.3xRE.sub.xD.sub.2+yE.sub.12yN.sub.20zO.sub.z:M, wherein EA is an element or a combination of elements from the group of divalent elements, RE is a rare earth element, D is an element or a combination of elements from the group of trivalent elements, E is an element or a combination of elements from the group of tetravalent elements, M is an activator element or a combination of activator elements, 0x3, 0y12 and z=yx, wherein z0. In particular, the phosphor comprises the molecular formula Ba.sub.3xLa.sub.xAl.sub.2+xSi.sub.12xN.sub.20:Ce.sup.3+. The phosphor 1 is present in the form of particles which comprise a particle size of between and including 500 nanometers and 100 micrometers, for example.

[0046] FIG. 2 shows a section of a crystal structure 2 of a host lattice 3 of a phosphor 1. The phosphor 1 comprises the molecular formula Ba.sub.3xLa.sub.xAl.sub.2+xSi.sub.12xN.sub.20:Ce.sup.3+. The crystal structure is shown from the direction of the crystallographic b-axis. As the electron densities of La and Ba as well as Si and Al are very similar, it is not possible to reliably distinguish between these atoms using X-ray diffraction. Therefore, no exact value for x can be specified. However, x=1.5 can be estimated from the composition of the reactants during the method for producing the phosphor. Crystallographic data for Ba.sub.3xLa.sub.xAl.sub.2+xSi.sub.12xN.sub.20:Ce.sup.3+ are summarized in Table 1. Table 2 shows crystallographic location parameters of Ba.sub.3xLa.sub.xAl.sub.2+xSi.sub.12xN.sub.20:Ce.sup.3+.

TABLE-US-00001 TABLE 1 Crystallographic data of Ba.sub.3xLa.sub.xAl.sub.2+xSi.sub.12xN.sub.20:Ce.sup.3+ molecular formula Ba.sub.3xLa.sub.xAl.sub.2+xSi.sub.12xN.sub.20:Ce.sup.3+ Crystal system Trigonal space group R3 Grid parameters a/pm 539.20(4) /90 b/pm 539.20(4) /90 c/pm 5124.9(5) /120 Volume V/nm.sup.3 1.2904(2) Crystallographic density /g cm.sup.3 4.165 T/K 296 (2) Diffractometer Bruker D8 Quest Radiation Cu K.sub. (154.178 nm) Measuring range 2.5773 70.0714 Measured/independent reflexes 10948/604 Measured reciprocal space 6 h 6; 6 k 6; 63 l 63 R.sub.all/wR.sub.ref 4.13%/10.24% GooF 1.168

TABLE-US-00002 TABLE 2 Crystallographic location parameters of Ba.sub.3xLa.sub.xAl.sub.2+xSi.sub.12xN.sub.20:Ce.sup.3+. Atom Wyckoff Name type location x Y z Occupation U.sub.iso Ba/La01 Ba/La 6c 1.0 1.0 0.64723(2) 1 0.0259(3) U.sub.ani Ba/La02 Ba/La 3b 0 0 0.5 1 0.0359(3) U.sub.ani Si01 Si 6c 0.333333 0.666667 0.53206(6) 1 0.0234(6) Si02 Si 6c 0.333333 0.666667 0.46757(6) 1 0.0238(6) Si03 Si 6c 0.666667 0.333333 0.62492(6) 1 0.0241(6) Si04 Si 6c 0.333333 0.666667 0.62719(6) 1 0.0250(7) Al01 Al 18f 0.3275(4) 0.9973(4) 0.57883(3) 1 0.0222(5) NO1 N 6c 0.333333 0.666667 0.49999(16) 1 0.0196(18) NO2 N 6c 0.666667 0.333333 0.59053(17) 1 0.024(2) NO3 N 18f 0.5290(12) 0.5239(12) 0.63802(10) 1 0.0290(12) NO4 N 6c 0 0 0.58881(19) 1 0.028(2) NO5 N 18f 0.4000(12) 0.9987(12) 0.54383(10) 1 0.0262(12) NO6 N 6c 0.333333 0.666667 0.59222(17) 1 0.028(2)

[0047] The section of the crystal structure 2 of the host lattice 3 of the phosphor 1 shown in FIG. 2 comprises on all sides corner-linked AlN.sub.4 tetrahedra 4 and on all sides corner-linked SiN.sub.4 tetrahedra 4. As described above, it is not possible to reliably distinguish between the AlN.sub.4 tetrahedra 4 and the SiN.sub.4 tetrahedra 4 by X-ray diffraction. The AlN.sub.4 and SiN.sub.4 tetrahedra 4 form a first layer 5, a second layer 6 and a third layer 7. Three corners of the SiN.sub.4 tetrahedra 4 and the AlN.sub.4 tetrahedra 4 are used for linking within one of the layers 5, 6, 7, the fourth corner of the SiN.sub.4 tetrahedra 4 and the AlN.sub.4 tetrahedra 4 is used for linking between the layers 5, 6, 7. The fourth corner points in the direction of the crystallographic c-axis. The first layer 5, the second layer 6 and the third layer 7 are each extended along the crystallographic a- and b-axis.

[0048] The Ba atoms 8 and the La atoms 8 are arranged between the layers 5, 6, 7. Due to the similar electron density of Ba and La, their positions cannot be distinguished. The activator element Ce.sup.3+ occupies part of the positions of the Ba atoms 8 and the La atoms 8.

[0049] The first layer 5, the second layer 6, and the third layer 7 form a layer stack 9. A layer stack 9 together with a further, inversion-symmetrically arranged layer stack 9 forms a layer packet 10. A layer packet 10 comprises six layers 5, 6, 7, in particular two first layers 5, two second layers 6 and two third layers 7. In the layer packet 10, two layers 7 are linked via the corners of the SiN.sub.4 and/or AlN.sub.4 tetrahedra 4, which are not used for linking within the layer 7.

[0050] FIG. 3 shows a layer stack 9 from the direction of the crystallographic c-axis. The first layer 5 of the layer stack 9 comprises six-membered rings 11. A six-membered ring 11 comprises a total of six AlN.sub.4 and/or SiN.sub.4 tetrahedra 4. The third layer 7 of the layer stack 9 also comprises six-membered rings 11. For better visibility of the structure of the first layer 5 and the third layer 7, a section of a single one of these layers 5, 7 is shown in FIG. 4. In layer 5, 7, an AlN.sub.4 and/or SiN.sub.4 tetrahedron 4 is connected with three further AlN.sub.4 and/or SiN.sub.4 tetrahedrons 4.

[0051] The second layer 6 comprises three-membered rings 12, which are formed from a total of three AlN.sub.4 and/or SiN.sub.4 tetrahedra 4. A section of the second layer 6 is shown in FIG. 5. In the second layer 6, an AlN.sub.4 and/or SiN.sub.4 tetrahedron 4 is connected with six further AlN.sub.4 and/or SiN.sub.4 tetrahedra 4.

[0052] FIG. 6 shows an emission spectrum E-VB of a phosphor 1 according to a comparative example with the molecular formula Lu.sub.3Al.sub.5O.sub.12:Ce.sup.3+. The emission spectrum E-VB is shown in a wavelength range of between and including 430 nanometers and 800 nanometers.

[0053] In FIG. 7 an emission spectrum E1 of a phosphor 1 according to the exemplary embodiment with the molecular formula Ba.sub.3xLa.sub.xAl.sub.2+xSi.sub.12xN.sub.20:Ce.sup.3+ is shown. The emission spectrum is shown in a wavelength range of between and including 380 nanometers and 800 nanometers. Spectral data of phosphor 1 with the molecular formula Ba.sub.3xLa.sub.xAl.sub.2+xSi.sub.12xN.sub.20:Ce.sup.3+ after excitation with electromagnetic radiation of a wavelength of about 408 nanometers are summarized in Table 3.

TABLE-US-00003 TABLE 3 Spectral data of Ba.sub.3xLa.sub.xAl.sub.2+xSi.sub.12xN.sub.20:Ce.sup.3+. Ba.sub.3xLa.sub.xAl.sub.2+xSi.sub.12xN.sub.20:Ce.sup.3++ excitation wavelength 408 nm dominant wavelength .sub.dom 488 nm peak wavelength .sub.max 474 nm FWHM 93 nm

[0054] FIG. 8 shows the emission spectra E-VB and E1 as well as a melanopic curve M. The emission spectra E-VB and E1 as well as the melanopic curve M are shown in a wavelength range of between and including 380 nanometers and 880 nanometers. The emission spectrum E1 of phosphor 1 with the molecular formula Ba.sub.3xLa.sub.xAl.sub.2+xSi.sub.12xN.sub.20:Ce.sup.3+ comprises a significantly larger overlap with the melanopic curve M than the emission spectrum E-VB of the comparative example with the molecular formula Lu.sub.3Al.sub.5O.sub.12:Ce.sup.3+. The larger overlap is also reflected in the comparison of the melanopic ELR and the relative melanopic ELR of Ba.sub.3xLa.sub.xAl.sub.2+xSi.sub.12xN.sub.20:Ce.sup.3+ and Lu.sub.3Al.sub.5O.sub.12:Ce.sup.3+, which are shown in Table 4.

TABLE-US-00004 TABLE 4 Comparison of the melanopic ELR. Ba.sub.3xLa.sub.xAl.sub.2+xSi.sub.12xN.sub.20:Ce.sup.3+ phosphor Lu.sub.3Al.sub.5O.sub.512:Ce.sup.3+ (excitation at 408 nm) melanopic ELR 0.6572 1.9970 relative melanopic 100% 304% ELR

[0055] In the exemplary embodiment of the method for producing a phosphor 1 shown in FIG. 9, reactants are provided in a method step S1. In the present case, the phosphor 1 has the molecular formula Ba.sub.3xLa.sub.xAl.sub.2+xSi.sub.12xN.sub.20:Ce.sup.3+. The reactants and their weights are summarized in Table 5.

TABLE-US-00005 TABLE 5 Weights for the synthesis of Ba.sub.3xLa.sub.xAl.sub.2+xSi.sub.12xN.sub.20:Ce.sup.3+. Exemplary embodiment x CeO.sub.2 BaN.sub.0.94 LaN Si.sub.3N.sub.4 AlN 1 1.5 0.100 2.5804 2.6072 4.0095 0.7029 g g g g g 2 1.5 0.100 3.8172 3.8564 1.1865 1.0399 g g g g g

[0056] The reactants are mixed in a further method step S2 to form a reactant mixture. Mixing takes place, for example, in a hand mortar, a mortar mill, a ball mill or a multi-axis mixer. The reactant mixture is then transferred to a crucible, for example made of tungsten.

[0057] The reactant mixture is then heated in a method step S3 to around 1850 C. for 4 hours at 20 bar under an N.sub.2 atmosphere or an atmosphere of an N.sub.2/H.sub.2 mixture (95/5%). After the reaction and cooling, the product is grinded. Grinding is carried out in a hand mortar, a mortar mill or a ball mill, for example.

[0058] The radiation emitting component 13 according to the exemplary embodiment of FIG. 10 comprises a semiconductor chip 14 which emits electromagnetic radiation of a first wavelength range during operation. The semiconductor chip 14 comprises a substrate 16 on which a semiconductor layer sequence 17 is epitaxially grown. The semiconductor layer sequence 17 comprises an active region 18. During operation of the radiation emitting component 13, the active region 18 generates electromagnetic radiation of the first wavelength range. In the present case, the semiconductor chip 14 emits electromagnetic radiation in the ultraviolet to blue wavelength range of the electromagnetic spectrum.

[0059] The radiation emitting component 13 further comprises a conversion element 15. The conversion element 14 is arranged on a side of the semiconductor layer sequence 17 that faces away from the substrate 16. In other words, the conversion element 15 is arranged downstream of the semiconductor chip 14. The conversion element 15 comprises a phosphor 1, for example Ba.sub.3xLa.sub.xAl.sub.2+xSi.sub.12xN.sub.20:Ce.sup.3+. In the present case, the conversion element 15 also comprises a further phosphor 19.

[0060] The phosphor 1 converts the electromagnetic radiation of the first wavelength range into electromagnetic radiation of a second wavelength range. The second wavelength range is at least partially different from the first wavelength range. The second phosphor 19 converts the electromagnetic radiation of the first wavelength range into electromagnetic radiation of a third wavelength range. The third wavelength range is at least partially different from the first wavelength range and/or the second wavelength range. For example, the second phosphor is a phosphor from the class of garnets, such as (Lu, Y, Yb, Gd, Tb).sub.3(Ga, Al, Si).sub.5O.sub.12:Ce.sup.3+. In the present case, the third wavelength range is the green to orange wavelength range of the electromagnetic spectrum.

[0061] It is further possible that the conversion element 15 comprises a third phosphor 20 which converts electromagnetic radiation of the first wavelength range into electromagnetic radiation of a fourth wavelength range which is at least partially different from the first wavelength range, the second wavelength range and/or the third wavelength range. In the present case, the fourth wavelength range is the red wavelength range of the electromagnetic spectrum. For example, the third phosphor 20 is a red-emitting nitride phosphor, such as (Ca, Ba, Sr).sub.2(Si, Al).sub.5(N, O).sub.8:Eu.sup.2+ or (Sr, Ca)AlSiN.sub.3:Eu.sup.2+.

[0062] In the present case, the radiation emitting component 13 emits a mixed light that comprises the electromagnetic radiation of the first wavelength range, the second wavelength range and the third wavelength range. In the present case, the mixed light is white light.

[0063] The features and exemplary embodiments described in connection with the figures may be combined with each other in accordance with further exemplary embodiments, even if not all combinations are explicitly described. Furthermore, the exemplary embodiments described in connection with the figures may alternatively or additionally comprise further features as described in the general part.

[0064] The present disclosure is not limited to the exemplary embodiments by the description thereof. Rather, the present disclosure includes any new feature as well as any combination of features, which includes in particular any combination of features in the patent claims, even if this feature or combination itself is not explicitly specified in the patent claims or exemplary embodiments.

LIST OF REFERENCE SIGNS

[0065] 1 phosphor [0066] 2 crystal structure [0067] 3 Host lattice [0068] 4 tetrahedron [0069] 5, 6, 7 layers [0070] 8 Ba/La atom [0071] 9 layer stack [0072] 10 layer packet [0073] 11 six-membered ring [0074] 12 three-membered ring [0075] 13 radiation emitting component [0076] 14 semiconductor chip [0077] 15 conversion element [0078] 16 substrate [0079] 17 semiconductor layer sequence [0080] 18 active region [0081] 19 second phosphor [0082] 20 third phosphor [0083] S1, S2, S3 method steps [0084] E-VB emission spectrum of Lu.sub.3Al.sub.5O.sub.12:Ce.sup.3+ [0085] E1 emission spectrum of Ba.sub.3xLa.sub.xAl.sub.2+xSi.sub.12xN.sub.20:Ce.sup.3+ [0086] M melanopic curve