Phosphor, method of producing a phosphor, and radiation emitting device

Abstract

A phosphor may have the general formula EA.sub.2A.sub.4D.sub.3O.sub.xN.sub.8-x:RE. EA may be selected from the group of divalent elements. A may be selected from the group of monovalent, divalent or trivalent elements. D may be selected from the group of trivalent or tetravalent elements. RE may be an activator element. 0≤x≤8, and ε(4+4y+3z)=3(8−x)+2x with the charge number y of element A, the charge number z of element D, and ε=0.9-1.1.

Claims

1. A phosphor with the general formula EA.sub.2A.sub.4D.sub.3O.sub.xN.sub.8-x:RE, wherein: EA is selected from the group of divalent elements; A is selected from the group consisting of monovalent elements, divalent elements, or trivalent elements; D is selected from the group consisting of trivalent elements or tetravalent elements; RE is an activator element; 0≤x≤8; and ε(4+4y+3z)=3(8−x)+2x with the charge number y of element A, the charge number z of element D, and ε=0.9-1.1.

2. The phosphor according to claim 1, wherein a host lattice of the phosphor comprises a structure with a monoclinic space group.

3. The phosphor according to claim 1, wherein the phosphor comprises a host lattice comprising D centered D(O,N).sub.4 tetrahedra, A centered A(O,N).sub.4 tetrahedra, A(O,N).sub.3+1 units, and A(O,N).sub.3 units.

4. The phosphor according to claim 3, wherein the host lattice comprises layers of corner-linked D(O,N).sub.4 tetrahedra, and the corner-linked D(O,N).sub.4 tetrahedra form eight-ring structures within the layers.

5. The phosphor according to claim 4, wherein the layers of corner-linked D(O,N).sub.4 tetrahedra are linked via A(O,N).sub.4 tetrahedra and/or A(O,N).sub.3+1 units and/or A(O,N).sub.3 units.

6. The phosphor according to claim 5, wherein the A(O,N).sub.4 tetrahedra and/or the A(O,N).sub.3+1 units and/or the A(O,N).sub.3 units linking the layers of corner-linked D(O,N).sub.4 tetrahedra form interstitial spaces, wherein at least one interstitial space contains an EA atom.

7. The phosphor according to claim 1, wherein EA is selected from the group consisting of Mg, Ca, Sr, Ba, or combinations thereof.

8. The phosphor according to claim 1, wherein A is selected from the group consisting of Li, Mg, Al, or combinations thereof.

9. The phosphor according to claim 1, wherein D is selected from the group consisting of Si, Al, or combinations thereof.

10. The phosphor according to claim 1, wherein RE is selected from the group consisting of rare earth metals.

11. The phosphor according to claim 1, wherein RE comprises Eu or Ce.

12. The phosphor according to claim 1, wherein the activator element comprises a molecular fraction ranging from 0.001 inclusive to 0.1 inclusive relative to EA.

13. The phosphor according to claim 1, wherein the phosphor comprises the formula Sr.sub.2Li.sub.4Si.sub.3O.sub.4N.sub.4:RE.

14. A method for producing a phosphor with the general formula EA.sub.2A.sub.4D.sub.3O.sub.xN.sub.8-x:RE, wherein: EA is selected from the group consisting of divalent elements; A is selected from the group consisting of monovalent elements, divalent elements, or trivalent elements; D is selected from the group consisting of trivalent elements or tetravalent elements; RE is an activator element; 0≤x≤8; and ε(4+4y+3z)=3(8−x)+2x with the charge number y of element A, the charge number z of element D, and ε=0.9-1.1, wherein the method comprises: providing a stoichiometric composition of reactants; and heating the reactants to a temperature ranging from 700° C. inclusive to 1100° C. inclusive.

15. A radiation emitting device comprising: a semiconductor chip configured to emit electromagnetic radiation of a first wavelength range; a conversion element comprising a phosphor with the general formula EA.sub.2A.sub.4D.sub.3O.sub.xN.sub.8-x:RE configured to convert electromagnetic radiation of the first wavelength range into electromagnetic radiation of a second wavelength range, wherein: EA is selected from the group consisting of divalent elements; A is selected from the group consisting of monovalent elements, divalent elements, or trivalent elements; D is selected from the group consisting of trivalent elements or tetravalent elements; RE is an activator element; 0≤x≤8; and ε(4+4y+3z)=3(8−x)+2x with the charge number y of element A, the charge number z of element D, and ε=0.9-1.1.

16. The radiation emitting device according to claim 15, wherein an emission maximum of the phosphor ranges from 500 nanometers inclusive to 600 nanometers inclusive.

17. The radiation emitting device according to claim 15, wherein a dominant wavelength of the phosphor ranges from 550 nanometers inclusive to 580 nanometers inclusive.

18. The radiation emitting device according to claim 15, wherein a spectral half-width of the emission of the phosphor ranges from 60 nanometers inclusive to 100 nanometers inclusive.

19. The radiation emitting device according to claim 15, wherein the conversion element is free of a further phosphor.

20. The radiation emitting device according to claim 15, wherein the conversion element comprises a second phosphor configured to convert electromagnetic radiation of the first wavelength range into electromagnetic radiation of a third wavelength range.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Further advantageous embodiments, configurations and developments of the phosphor, the method for producing a phosphor and the radiation emitting device result from the following exemplary embodiments shown in conjunction with the figures.

(2) FIGS. 1A-D and 2A-D show sections from different perspectives of the host lattice of the phosphor according to an exemplary embodiment,

(3) FIGS. 3 and 4 each show a radiation emitting device according to exemplary embodiments,

(4) FIG. 5 shows an emission spectrum of the phosphor according to an exemplary embodiment, and

(5) FIG. 6 shows an emission spectrum of the phosphor according to an exemplary embodiment and a comparative example.

(6) Identical, similar or similar-acting elements are shown in the figures with the same reference signs. The figures and the proportions of the elements shown in the figures with respect to one another are not to be regarded as true to scale. Rather, individual elements, in particular layer thicknesses, can be shown exaggeratedly large for better representability and/or better understanding.

DETAILED DESCRIPTION

(7) The exemplary embodiment Sr.sub.2Li.sub.4Si.sub.3O.sub.4N.sub.4:Eu.sup.2+ of phosphor 1 was synthesized as follows: A stoichiometric composition of the reactants Li.sub.3N, Li.sub.2O, Si.sub.3N.sub.4, SiO.sub.2, Sr.sub.3N.sub.2, SrO and Eu.sub.2O.sub.3 were provided and heated in a nickel crucible under 100 bar nitrogen atmosphere at 900° C. for 16 hours.

(8) Tab. 1 below shows the crystallographic data of the exemplary embodiment Sr.sub.2Li.sub.4Si.sub.3O.sub.4N.sub.4:Eu.sup.2+ of phosphor 1. For the monoclinic space group, the angles α and γ are equal to 90° and β is not equal to 90°, and the lattice parameters a, b and c differ from one another. The mixed occupation of europium and strontium was not considered in the structure refinement due to the small atomic fraction of europium.

(9) In Tab. 1, the measured section of the reciprocal space is specified by the limits of the corresponding Miller indices (hkl). Furthermore, the conventional R-value of all reflections R.sub.all is specified, which indicates the mean percentage deviation between observed and calculated structure factors. The weighted R-value wR.sub.ref contains a weighting factor that weights the reflexes according to a defined scheme inter alia depending on their standard deviation. For a good structural model, R.sub.all should be below 5% and wR.sub.ref below 10%. As a further quality feature for the agreement of calculated and measured structure, the goodness of fit (GoF) is specified, which should be close to 1.

(10) The reliability factors and the goodness of fit factor are in the desired regions for the exemplary embodiment Sr.sub.2Li.sub.4Si.sub.3O.sub.4N.sub.4:Eu.sup.2+ of phosphor 1.

(11) TABLE-US-00001 TABLE 1 molecular formula Sr.sub.2Li.sub.4Si.sub.3O.sub.4N.sub.4: Eu.sup.2+ formula mass/g mol.sup.−1 407.3   Z 2    crystal system monoclinic space group Cm lattice parameters a/pm 516.11(8) b/pm 1479.7(2)  c/pm 541.21(9) α/° 90    β/°  111.706(9) γ/° 90    volume V/nm.sup.3     0.38401(11) crystallographic density ρ/g cm.sup.−3 3.523 T/K 296(2)   diffractometer BRUKER D8 Quest radiation Cu K.sub.α (154.178 nm) measuring range 5.981 ≤ θ ≤ 67.946 measured reflexes 1802     independent reflexes 689     measured reciprocal space −6 ≤ h ≤ 6; −17 ≤ k ≤ 17; −6 ≤ l ≤ 6 R.sub.all  2.57% wR.sub.ref  5.38% GoF 1.033

(12) Tab. 2 below shows the Wyckoff position, the atomic positions x, y and z, the occupations and the isotropic deflection parameters Uiso for atoms of the exemplary embodiment Sr.sub.2Li.sub.4Si.sub.3O.sub.4N.sub.4:Eu.sup.2+ of phosphor 1.

(13) The Wyckoff position describes the symmetry of the Wyckoff positions according to R. W. G. Wyckoff. U.sub.iso is the radius of the isotropic deflection parameter of the respective atom. The position LiO3 is only half occupied. This position thus characterizes the trigonal-planar surrounded symmetrically equivalent positions for Li atoms, which are mutually exclusively occupied.

(14) TABLE-US-00002 TABLE 2 Wyckoff atom position x y z occupation U.sub.iso Sr01 4b 0.6821(2) 0.35944(4) 0.1201(2) 1 0.0136(2) Si02 2a 0.4907(8) 0.5 0.6299(7) 1 0.0089(7) Si03 4b 0.3369(5) 0.30886(18) 0.4946(4) 1 0.0091(5) O004 2a 0.568(2) 0.5 0.357(2) 1 0.011(2) O005 4b 0.196(2) 0.3219(4) 0.1654(12) 1 0.0146(16) N006 4b 0.683(2) 0.2809(4) 0.590(2) 1 0.0104(17) O007 2a 0.799(3) 0.5 0.881(3) 1 0.016(3) N008 4b 0.2895(16) 0.4073(5) 0.6440(15) 1 0.0118(14) Li01 2a 0.983(7) 0.5 0.614(6) 1 0.023(6) Li02 4b 0.055(4) 0.3287(13) 0.794(4) 1 0.019(4) Li03 4b 0.177(15) 0.467(2) 0.107(14) 0.5 0.033(8)

(15) FIGS. 1A-D show sections of the host lattice of an exemplary embodiment of phosphor 1 with the formula Sr.sub.2Li.sub.4Si.sub.3O.sub.4N.sub.4:Eu.sup.2+ in the bc plane (side view) and FIGS. 2A-D show sections of the same host lattice in the ab plane orthogonal to the bc plane (top view). In FIGS. 1A-C and 2A-C, selected atoms and bonds are not shown for ease of visualization and understanding of the structure.

(16) FIG. 1A shows three layers of corner-linked schematically represented Si(O,N).sub.4 tetrahedra 2 arranged on top of each other. All other atoms of the host lattice of the phosphor Sr.sub.2Li.sub.4Si.sub.3O.sub.4N.sub.4:Eu.sup.2+ are not shown. The Si(O,N).sub.4 tetrahedra 2 within a layer are linked to each other via an oxygen atom or a nitrogen atom. The Si(O,N).sub.4 tetrahedra 2 from different layers are not directly linked to each other.

(17) FIG. 2A shows the top view of the structure of FIG. 1A. For clarity, only one layer of corner-linked Si(O,N).sub.4 tetrahedra 2 is shown. Each Si(O,N).sub.4 tetrahedron 2 is linked within the layer with at least two further Si(O,N).sub.4 tetrahedra 2 via one corner each. Eight Si(O,N).sub.4 tetrahedra 2 each form a ring structure. The layer of corner-linked Si(O,N).sub.4 tetrahedra 2 includes at least one eight-ring structure. In particular, the layer of corner-linked Si(O,N).sub.4 tetrahedra 2 comprises a plurality of interconnected eight-ring structures.

(18) FIG. 1B shows the side view from FIG. 1A, in which Li(O,N).sub.4 tetrahedra 4 and Li(O,N).sub.3+1 units 3 are additionally shown. The Si(O,N).sub.4 tetrahedra 2 and the Li(O,N).sub.4 tetrahedra 4 or the Li(O,N).sub.3+1 units 3 are corner-linked. The Li(O,N).sub.4 tetrahedra 4 or the Li(O,N).sub.3+1 units 3 connect the layers of corner-linked Si(O,N).sub.4 tetrahedra 2 to each other. A Li(O,N).sub.4 tetrahedron 4 or a Li(O,N).sub.3+1 unit 3 may be linked with at least two Si(O,N).sub.4 tetrahedra 2 from one or two adjacent layers of corner-linked Si(O,N).sub.4 tetrahedra 2. In particular, the Li(O,N).sub.3+1 units 3 link the Si(O,N).sub.4 tetrahedra 2 from two adjacent layers of corner-linked Si(O,N).sub.4 tetrahedra 2 and the Li(O,N).sub.4 tetrahedra 4 link the Si(O,N).sub.4 tetrahedra 2 within one layer of corner-linked Si(O,N).sub.4 tetrahedra 2. In particular, Si(O,N).sub.4 tetrahedra 2 are only linked within their own layer via Li(O,N).sub.4 tetrahedra 4, but not with an adjacent layer.

(19) FIG. 2B shows the top view of the structure of FIG. 1B. For reasons of clarity, only one layer of corner-linked Si(O,N).sub.4 tetrahedra 2 and only Li(O,N).sub.4 tetrahedra 4 and Li(O,N).sub.3+1 units 3 linking downward and within the layer are shown.

(20) FIG. 1C shows the side view from FIG. 1B, in which the two symmetrically equivalent positions 5 for the Li atom of the Li(O,N).sub.3 units are additionally shown. FIG. 2C shows the top view of the structure of FIG. 1C. The occupation of the symmetrically equivalent positions 5 with a Li atom is mutually exclusive. Thus, only one of the two symmetrically equivalent positions 5 is always occupied with a Li atom. The Li(O,N).sub.3 units are arranged between the layers of corner-linked D(O,N).sub.4 tetrahedra 2 and link two adjacent layers together.

(21) FIG. 1D shows the side view from FIG. 1C, in which the Sr atoms 6 are additionally shown. FIG. 2D shows the top view of the structure of FIG. 1D. The Sr atoms 6 are arranged in interstitial spaces between the Li(O,N).sub.4 tetrahedra 4 and/or the Li(O,N).sub.3+1 units 3 and/or the Li(O,N).sub.3 units linking the layers of corner-linked Si(O,N).sub.4 tetrahedra 2. In particular, the Sr atoms 6 are arranged between the layers of corner-linked Si(O,N).sub.4 tetrahedra 2. Part of the Sr atoms 6 may be replaced by Eu.sup.2+ ions. In particular, the molecular fraction of Eu.sup.2+ relative to Sr may be between 0.001 inclusive and 0.1 inclusive.

(22) Further exemplary embodiments of phosphor 1 are shown in Table 3.

(23) TABLE-US-00003 TABLE 3 exemplary embodiments of phosphor 1 no. molecular formula 1 Sr.sub.2Li.sub.4Si.sub.3O.sub.4N.sub.4: Eu.sup.2+ 2 Ca.sub.2Li.sub.4Si.sub.3O.sub.4N.sub.4: Eu.sup.2+ 3 Ba.sub.2Li.sub.4Si.sub.3O.sub.4N.sub.4: Eu.sup.2+ 4 Sr.sub.2Li.sub.4Zr.sub.3O.sub.4N.sub.4: Eu.sup.2+ 5 Ca.sub.2Li.sub.4Zr.sub.3O.sub.4N.sub.4: Eu.sup.2+ 6 Ba.sub.2Li.sub.4Zr.sub.3O.sub.4N.sub.4: Eu.sup.2+ 7 Sr.sub.2Li.sub.4Hf.sub.3O.sub.4N.sub.4: Eu.sup.2+ 8 Ca.sub.2Li.sub.4Hf.sub.3O.sub.4N.sub.4: Eu.sup.2+ 9 Ba.sub.2Li.sub.4Hf.sub.3O.sub.4N.sub.4: Eu.sup.2+ 10 Sr.sub.2Mg.sub.4Si.sub.3N.sub.8: Eu.sup.2+ 11 Sr.sub.2(Mg.sub.3Li)Al.sub.3O.sub.4N.sub.4: Eu.sup.2+ 12 Sr.sub.2Li.sub.4Al.sub.3O.sub.7N: Eu.sup.2+ 13 Ca.sub.2Mg.sub.4Si.sub.3N.sub.8: Eu.sup.2+ 14 Ca.sub.2(Mg.sub.3Li)Al.sub.3O.sub.4N.sub.4: Eu.sup.2+ 15 Ca.sub.2Li.sub.4Al.sub.3O.sub.7N: Eu.sup.2+ 16 Ba.sub.2Mg.sub.4Si.sub.3N.sub.8: Eu.sup.2+ 17 Ba.sub.2(Mg.sub.3Li)Al.sub.3O.sub.4N.sub.4: Eu.sup.2+ 18 Ba.sub.2Li.sub.4Al.sub.3O.sub.7N: Eu.sup.2+ 19 Sr.sub.2Li.sub.4Ge.sub.3O.sub.4N.sub.4: Eu.sup.2+ 20 Ca.sub.2Li.sub.4Ge.sub.3O.sub.4N.sub.4: Eu.sup.2+ 21 Ba.sub.2Li.sub.4Ge.sub.3O.sub.4N.sub.4: Eu.sup.2+ 22 Sr.sub.2Mg.sub.4Ge.sub.3N.sub.8: Eu.sup.2+ 23 Sr.sub.2(Mg.sub.3Li)Ga.sub.3O.sub.4N.sub.4: Eu.sup.2+ 24 Sr.sub.2Li.sub.4Ga.sub.3O.sub.7N: Eu.sup.2+ 25 Ca.sub.2Mg.sub.4Ge.sub.3N.sub.8: Eu.sup.2+ 26 Ca.sub.2(Mg.sub.3Li)Ga.sub.3O.sub.4N.sub.4: Eu.sup.2+ 27 Ca.sub.2Li.sub.4Ga.sub.3O.sub.7N: Eu.sup.2+ 28 Ba.sub.2Mg.sub.4Ge.sub.3N.sub.8: Eu.sup.2+ 29 Ba.sub.2(Mg.sub.3Li)Ga.sub.3O.sub.4N.sub.4: Eu.sup.2+ 30 Ba.sub.2Li.sub.4Ga.sub.3O.sub.7N: Eu.sup.2+ 31 Sr.sub.2(Mg.sub.3Li)Si.sub.3ON.sub.7: Eu.sup.2+ 32 Ca.sub.2(Mg.sub.3Li)Si.sub.3ON.sub.7: Eu.sup.2+ 33 Ba.sub.2(Mg.sub.3Li)Si.sub.3ON.sub.7: Eu.sup.2+ 34 Sr.sub.2Li.sub.4Si.sub.3O.sub.4N.sub.4: Ce.sup.2+ 35 Ca.sub.2Li.sub.4Si.sub.3O.sub.4N.sub.4: Ce.sup.2+ 36 Ba.sub.2Li.sub.4Si.sub.3O.sub.4N.sub.4: Ce.sup.2+ 37 Sr.sub.2Li.sub.4Zr.sub.3O.sub.4N.sub.4: Ce.sup.2+ 38 Ca.sub.2Li.sub.4Zr.sub.3O.sub.4N.sub.4: Ce.sup.2+ 39 Ba.sub.2Li.sub.4Zr.sub.3O.sub.4N.sub.4: Ce.sup.2+ 40 Sr.sub.2Li.sub.4Hf.sub.3O.sub.4N.sub.4: Ce.sup.2+ 41 Ca.sub.2Li.sub.4Hf.sub.3O.sub.4N.sub.4: Ce.sup.2+ 42 Ba.sub.2Li.sub.4Hf.sub.3O.sub.4N.sub.4: Ce.sup.2+ 43 Sr.sub.2Mg.sub.4Si.sub.3N.sub.8: Ce.sup.2+ 44 Sr.sub.2(Mg.sub.3Li)Al.sub.3O.sub.4N.sub.4: Ce.sup.2+ 45 Sr.sub.2Li.sub.4Al.sub.3O.sub.7N: Ce.sup.2+ 46 Ca.sub.2Mg.sub.4Si.sub.3N.sub.8: Ce.sup.2+ 47 Ca.sub.2(Mg.sub.3Li)Al.sub.3O.sub.4N.sub.4: Ce.sup.2+ 48 Ca.sub.2Li.sub.4Al.sub.3O.sub.7N: Ce.sup.2+ 49 Ba.sub.2Mg.sub.4Si.sub.3N.sub.8: Ce.sup.2+ 50 Ba.sub.2(Mg.sub.3Li)Al.sub.3O.sub.4N.sub.4: Ce.sup.2+ 51 Ba.sub.2Li.sub.4Al.sub.3O.sub.7N: Ce.sup.2+ 52 Sr.sub.2Li.sub.4Ge.sub.3O.sub.4N.sub.4: Ce.sup.2+ 53 Ca.sub.2Li.sub.4Ge.sub.3O.sub.4N.sub.4: Ce.sup.2+ 54 Ba.sub.2Li.sub.4Ge.sub.3O.sub.4N.sub.4: Ce.sup.2+ 55 Sr.sub.2Mg.sub.4Ge.sub.3N.sub.8: Ce.sup.2+ 56 Sr.sub.2(Mg.sub.3Li)Ga.sub.3O.sub.4N.sub.4: Ce.sup.2+ 57 Sr.sub.2Li.sub.4Ga.sub.3O.sub.7N: Ce.sup.2+ 58 Ca.sub.2Mg.sub.4Ge.sub.3N.sub.8: Ce.sup.2+ 59 Ca.sub.2(Mg.sub.3Li)Ga.sub.3O.sub.4N.sub.4: Ce.sup.2+ 60 Ca.sub.2Li.sub.4Ga.sub.3O.sub.7N: Ce.sup.2+ 61 Ba.sub.2Mg.sub.4Ge.sub.3N.sub.8: Ce.sup.2+ 62 Ba.sub.2(Mg.sub.3Li)Ga.sub.3O.sub.4N.sub.4: Ce.sup.2+ 63 Ba.sub.2Li.sub.4Ga.sub.3O.sub.7N: Ce.sup.2+ 64 Sr.sub.2(Mg.sub.3Li)Si.sub.3ON.sub.7: Ce.sup.2+ 65 Ca.sub.2(Mg.sub.3Li)Si.sub.3ON.sub.7: Ce.sup.2+ 66 Ba.sub.2(Mg.sub.3Li)Si.sub.3ON.sub.7: Ce.sup.2+

(24) Further exemplary embodiments of phosphor 1 are the mixed crystal series between the end phases listed in Tab. 3. Selected examples are shown in Tab. 4.

(25) TABLE-US-00004 TABLE 4 exemplary embodiments of phosphor 1 no. 67 Sr.sub.1−αCa.sub.α).sub.2Li.sub.4Si.sub.3O.sub.4N.sub.4: Eu.sup.2+, α = 0-1 68 (Sr.sub.1−αBa.sub.α).sub.2Li.sub.4Si.sub.3O.sub.4N.sub.4: Eu.sup.2+, α = 0-1 69 (Ca.sub.1−αBa.sub.α).sub.2Li.sub.4Si.sub.3O.sub.4N.sub.4: Eu.sup.2+, α = 0-1 70 Sr.sub.2(Mg.sub.αLi.sub.4−α)Si.sub.3O.sub.4−αN.sub.4+α: Eu.sup.2+, α = 0-4 71 Ca.sub.2(Mg.sub.αLi.sub.4−α)Si.sub.3O.sub.4−αN.sub.4+α: Eu.sup.2+, α = 0-4 72 Ba.sub.2(Mg.sub.αLi.sub.4−α)Si.sub.3O.sub.4−αN.sub.4+α: Eu.sup.2+, α = 0-4 73 Sr.sub.2(Mg.sub.αLi.sub.4−α)Si.sub.3−αAl.sub.αO.sub.4N.sub.4: Eu.sup.2+, α = 0-3 74 Ca.sub.2(Mg.sub.αLi.sub.4−α)Si.sub.3−αAl.sub.αO.sub.4N.sub.4: Eu.sup.2+, α = 0-3 75 Ba.sub.2(Mg.sub.αLi.sub.4−α)Si.sub.3−αAl.sub.αO.sub.4N.sub.4: Eu.sup.2+, α = 0-3 76 Sr.sub.1−αCa.sub.α).sub.2Li.sub.4Si.sub.3O.sub.4N.sub.4: Ce.sup.2+, α = 0-1 77 (Sr.sub.1−αBa.sub.α).sub.2Li.sub.4Si.sub.3O.sub.4N.sub.4: Ce.sup.2+, α = 0-1 78 (Ca.sub.1−αBa.sub.α).sub.2Li.sub.4Si.sub.3O.sub.4N.sub.4: Ce.sup.2+, α = 0-1 79 Sr.sub.2(Mg.sub.αLi.sub.4−α)Si.sub.3O.sub.4−αN.sub.4+α: Ce.sup.2+, α = 0-4 80 Ca.sub.2(Mg.sub.αLi.sub.4−α)Si.sub.3O.sub.4−αN.sub.4+α: Ce.sup.2+, α = 0-4 81 Ba.sub.2(Mg.sub.αLi.sub.4−α)Si.sub.3O.sub.4−αN.sub.4+α: Ce.sup.2+, α = 0-4 82 Sr.sub.2(Mg.sub.αLi.sub.4-α)Si.sub.3−αAl.sub.αO.sub.4N.sub.4: Ce.sup.2+, α = 0-3 83 Ca.sub.2(Mg.sub.αLi.sub.4−α)Si.sub.3−αAl.sub.αO.sub.4N.sub.4: Ce.sup.2+, α = 0-3 84 Ba.sub.2(Mg.sub.αLi.sub.4−α)Si.sub.3−αAl.sub.αO.sub.4N.sub.4: Ce.sup.2+, α = 0-3

(26) FIG. 3 shows a schematic cross-sectional view of a radiation emitting device 10 according to an exemplary embodiment comprising a semiconductor chip 11 that emits primary radiation during operation of the radiation emitting device. The semiconductor chip 11 includes an active layer sequence and an active region (not explicitly shown here) for generating the primary radiation. The primary radiation is electromagnetic radiation of a first wavelength range. In a further embodiment, the primary radiation is electromagnetic radiation with wavelengths in the visible region, for example, the blue region. The primary radiation is emitted through the radiation exit surface 12. A beam path is thereby generated or the primary radiation follows a beam path.

(27) A conversion element 13 is arranged in the beam path of the primary radiation emitted by the semiconductor chip 11. The conversion element 13 is configured to absorb the primary radiation and to convert it at least partially into a secondary radiation with a second wavelength range. In particular, the secondary radiation comprises a longer wavelength than the absorbed primary radiation.

(28) The conversion element 13 comprises a phosphor 1 with the general formula EA.sub.2A.sub.4D.sub.3O.sub.xN.sub.8-x:RE. In particular, the conversion element 13 may comprise the phosphor 1 with the formula Sr.sub.2Li.sub.4Si.sub.3O.sub.4N.sub.4:Eu.sup.2+. The phosphor 1 can be embedded in a matrix material. For example, the matrix material is a silicone, a polysiloxane, an epoxy resin, or glass. Alternatively, the conversion element 13 may be free of a matrix material. In this case, the conversion element 13 can be made of the phosphor 1, for example, a ceramic of the phosphor 1.

(29) In particular, the conversion element 13 is free of a further phosphor. If the conversion element 13 converts only a portion of the primary radiation and transmits the remaining portion of the primary radiation, the combination of transmitted blue primary radiation and converted yellow secondary radiation can produce cold white mixed light with a low color rendering index R.sub.a. Alternatively, the conversion element 13 does not transmit the primary radiation, but converts the primary radiation almost completely into secondary radiation. As a result, the conversion element 13 emits secondary radiation in the yellow or yellow-green spectral range without a blue component.

(30) Alternatively, the conversion element 13 may comprise a second phosphor that converts the primary radiation into, for example, red secondary radiation. By combining the blue primary radiation, the yellow secondary radiation and the red secondary radiation, warm white mixed light can be produced.

(31) In the exemplary embodiment shown in FIG. 3, the semiconductor chip 11 and the conversion element 13 are embedded in a recess 15 of a housing 14. For better stabilization and protection of the semiconductor chip 11 and the conversion element 13, the recess 15 of the housing 14 can be filled with a casting 16. In particular, the recess 15 is completely filled with the casting 16 and the semiconductor chip 11 and the conversion element 13 are completely surrounded by the casting 16.

(32) The conversion element 13 can be arranged in direct mechanical contact on the semiconductor chip 11 as shown in FIG. 3. In particular, the radiation exit surface 12 forms the common surface between the conversion element 13 and the semiconductor chip 11. Alternatively, other layers such as adhesive layers may be located between the semiconductor chip 11 and the conversion element 13.

(33) According to the exemplary embodiment shown in FIG. 4, the conversion element 13 is arranged with a distance from the semiconductor chip 11. In this case, a casting 16 may be arranged between the semiconductor chip 11 and the conversion element 13. Alternatively, the recess 15 between the semiconductor chip and the conversion element may be free of any casting or further layers or components.

(34) FIG. 5 shows an emission spectrum of the exemplary embodiment Sr.sub.2Li.sub.4Si.sub.3O.sub.4N.sub.4:Eu.sup.2+ of phosphor 1 after excitation with blue primary radiation with a wavelength of 448 nm. The relative intensity I in percent is plotted against the wavelength λ in nm. The emission spectrum shows a narrow-band emission in the yellow wavelength range with a dominant wavelength λ.sub.D of 566 nm and an emission maximum of 554 nm. The spectral half-width of the emission is 85 nm.

(35) FIG. 6 shows the emission spectra of phosphor 1 according to the exemplary embodiment with the formula Sr.sub.2Li.sub.4Si.sub.3O.sub.4N.sub.4:Eu.sup.2+ (6-1) and a comparative example (6-2), a commercial garnet phosphor of the type Y.sub.3Al.sub.5O.sub.12:Ce.sup.3+. The relative intensity I in percent is plotted against the wavelength λ in nm. The Y.sub.3Al.sub.5O.sub.12:Ce.sup.3+ type garnet phosphor emits in the yellow spectral range and comprises a comparable color impression measured by the dominant wavelength λ.sub.D. Tab. 3 below compares the visual properties of phosphor 1 and the comparative example.

(36) TABLE-US-00005 TABLE 3 phosphor λ.sub.D spectral half- width $\frac{{\eta }_V\left(\mathrm{phosphor}\right)}{{\eta }_V\left(Y_3{\mathrm{Al}}_5{O}_{12}:{\mathrm{Ce}}^{3+}\right)}$ Y.sub.3Al.sub.5O.sub.12:Ce.sup.3+ 567 nm 116 nm 100% Sr.sub.2Li.sub.4Si.sub.3O.sub.4N.sub.4:Eu.sup.2+ 566 nm  85 nm 114%

(37) At a comparable dominant wavelength λ.sub.D, the phosphor Sr.sub.2Li.sub.4Si.sub.3O.sub.4N.sub.4:Eu.sup.2+ comprises a significantly smaller spectral half-width with 85 nm than the comparative example Y.sub.3Al.sub.5O.sub.12:Ce.sup.3+ with 116 nm. This smaller spectral half-width results in a significantly increased luminous efficacy, as shown in Tab. 3 based on the relative luminous efficacy

(38) $\frac{{\eta }_V\left(\mathrm{phosphor}\right)}{{\eta }_V\left(Y_3{\mathrm{Al}}_5{O}_{12}:{\mathrm{Ce}}^{3+}\right)}.$
The relative luminous efficacy increased by about 14% for the phosphor Sr.sub.2Li.sub.4Si.sub.3O.sub.4N.sub.4:Eu.sup.2+ is directly beneficial for conversion applications. When used as a single phosphor, this increased luminous efficacy is equivalent to the efficiency gain of the conversion solution when using the Sr.sub.2Li.sub.4Si.sub.3O.sub.4N.sub.4:Eu.sup.2+ phosphor instead of the conventional Y.sub.3Al.sub.5O.sub.12:Ce.sup.3+ type garnet phosphor. Efficiency gains can also be achieved when using the Sr.sub.2Li.sub.4Si.sub.3O.sub.4N.sub.4:Eu.sup.2+ phosphor in a conversion solution with multiple phosphors, for example in white-emitting light-emitting diodes.

(39) The features and exemplary embodiments described in conjunction with the figures can be combined with each other according to further exemplary embodiments, even if not all combinations are explicitly described. Furthermore, the exemplary embodiments described in conjunction with the figures may alternatively or additionally comprise further features according to the description in the general part.

(40) The invention is not limited to the exemplary embodiments by the description based thereon. Rather, the invention encompasses any new feature as well as any combination of features, which in particular includes 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.

(41) The present patent application claims priority of German patent application DE 10 2019 122 063.7, the disclosure content of which is hereby incorporated by reference.

REFERENCES

(42) 1 Phosphor 2 Si(O,N).sub.4 tetraeder 3 Li(O,N).sub.3+1 unit 4 Li(O,N).sub.4 tetraeder 5 symmetrically equivalent positions 6 Sr atom 10 radiation emitting device 11 semiconductor chip 12 radiation emitting area 13 conversion element 14 housing 15 recess 16 casting