PHOSPHORS

Abstract

The present invention relates to compounds of the formula I,

(A.sub.2-2nB.sub.n).sub.x(Ge.sub.1-mM.sub.m).sub.yO.sub.(x+2y):Mn.sup.4+I

in which the parameters A, B, M, m, n, x, and y have one of the meanings according to claim 1. Furthermore, the invention relates to a process for the preparation of the compounds of the formula I, to the use of these compounds as conversion phosphors, and to an emission-converting material comprising at least one compound of the formula I. The present invention furthermore relates to a light-emitting device which comprises at least one compound of the formula I according to the invention.

Claims

1. Compound of the formula I,
(A.sub.2-2nB.sub.n).sub.x(Ge.sub.1-mM.sub.m).sub.yO.sub.(x+2y):Mn.sup.4+I in which A corresponds to at least one element selected from the group of Li, Na, K and Rb, B corresponds to (C.sub.1-uD.sub.u), C corresponds to at least one element selected from the group of Ca, Ba and Sr, D corresponds to at least one element selected from the group of Ca and Ba, M corresponds to at least one element selected from the group of Ti, Zr, Hf, Si and Sn, 0n1, 0<u1, 0.5x2, 0m<1, and 1y9.

2. Compound according to claim 1, characterised in that n is equal to 0.

3. Compound according to claim 1, characterised in that the compound of the formula I is selected from the group of the compounds of the formula Ia,
(A.sub.2).sub.x(Ge.sub.1-m-zM.sub.mMn.sub.z).sub.yO.sub.(x+2y)Ia in which A, M, x, y and m have one of the meanings indicated under claim 1, and 0<z0.01*y.

4. Compound according to claim 1, characterised in that x is equal to 1.

5. Compound according to claim 1, characterised in that y is equal to 4.

6. Compound according to claim 1, characterised in that the compound is selected from the group of the compounds of the formulae Ia-1 to Ia-4,
A.sub.2Ge.sub.1-zMn.sub.zM.sub.3O.sub.9Ia-1
A.sub.2Ge.sub.2-zMn.sub.zM.sub.2O.sub.9Ia-2
A.sub.2Ge.sub.3-zMn.sub.zMO.sub.9Ia-3
A.sub.2Ge.sub.4-zMn.sub.zO.sub.9Ia-4 in which M, z and A have one of the meanings indicated under claim 1.

7. Compound according to claim 1, characterised in that M is equal to Si.

8. Compound according to claim 1, characterised in that 0.001z0.004.

9. Compound according to claim 1, characterised in that A corresponds to at least two elements selected from the group of Li, Na, K and Rb.

10. Process for the preparation of a compound according to claim 1, characterised in that suitable starting materials or corresponding reactive forms are mixed in a step a), and the mixture is thermally treated in a step b).

11. Process according to claim 10, in which the starting materials in step a) are selected from the group of corresponding oxides, carbonates and oxalates.

12. A method which comprises partially or completely converting a blue or near-UV emission into visible light of a longer wavelength using a compound according to claim 1.

13. Emission-converting material comprising at least one compound according to claim 1 and one or more further conversion phosphors.

14. Light source having at least one primary light source, characterised in that the light source comprises at least one compound according to claim 1.

15. Light source according to claim 14, in which the primary light source corresponds to a luminescent indium aluminium gallium nitride and/or indium gallium nitride.

16. Lighting unit, in particular for the backlighting of display devices, characterised in that it contains at least one light source according to claim 14.

17. Display device, in particular liquid-crystal display device (LC display), having backlighting, characterised in that it contains at least one lighting unit according to claim 16.

Description

EXAMPLES

a) Na.SUB.1.8.Li.SUB.0.2.Ge.SUB.0.999.Mn.SUB.0.0001.Si.SUB.3.O.SUB.9

[0093] 0.9539 g (9.000 mmol) of Na.sub.2CO.sub.3, 0.0739 g (1.000 mmol) of Li.sub.2CO.sub.3, 1.0453 g (9.990 mmol) of GeO.sub.2, 1.8025 g (30.000 mmol) of SiO.sub.2 and 0.0018 g (0.010 mmol) of MnC.sub.2O.sub.4.2H.sub.2O are thoroughly triturated with acetone in an agate mortar. The powder is dried, transferred into a covered porcelain crucible and calcined at 600 C. for 1 hour. The calcined powder is thoroughly triturated with acetone in an agate mortar together with 2.5% by weight of NaF and 2.5% by weight of LiF. The dried powder is transferred into a covered porcelain crucible and heated at 800 C. for 4 hours.

b) K.SUB.2.Ge.SUB.3.996.Mn.SUB.0.004.O.SUB.9

[0094] 1.3820 g (10.000 mmol) of K.sub.2CO.sub.3, 4.1814 g (39.960 mmol) of GeO.sub.2 and 0.0072 g (0.040 mmol) of MnC.sub.2O.sub.4.2H.sub.2O are thoroughly triturated with acetone in an agate mortar. The powder is dried, transferred into a covered porcelain crucible and calcined at 600 C. for 1 hour. The calcined powder is thoroughly triturated with acetone in an agate mortar together with 5% by weight of KF. The dried powder is transferred into a covered porcelain crucible and heated at 800 C. for 4 hours.

c) Rb.SUB.2.Ge.SUB.3.996.Mn.SUB.0.004.O.SUB.9

[0095] 2.3095 g (10.000 mmol) of Rb.sub.2CO.sub.3, 4.1814 g (39.960 mmol) of GeO.sub.2 and 0.0072 g (0.040 mmol) of MnC.sub.2O.sub.4.2H.sub.2O are thoroughly triturated with acetone in an agate mortar. The powder is dried, transferred into a covered porcelain crucible and calcined at 600 C. for 1 hour. The calcined powder is thoroughly triturated with acetone in an agate mortar together with 5% by weight of RbF. The dried powder is transferred into a covered porcelain crucible and heated at 780 C. for 4 hours.

d) K.SUB.2.SiGe.SUB.2.997.Mn.SUB.0.003.O.SUB.9

[0096] 1.5202 g (11.000 mmol) of K.sub.2CO.sub.3, 0.6008 g (10.00 mmol) of SiO.sub.2, 3.1360 g (29.970 mmol) of GeO.sub.2 and 0.0054 g (0.030 mmol) of MnC.sub.2O.sub.4.2H.sub.2O are thoroughly triturated with acetone in an agate mortar. The powder is dried, transferred into a covered porcelain crucible and calcined at 850 C. for 4 hours.

e) Production of a Pc-LED Using a Phosphor of the Composition K.SUB.2.Ge.SUB.3.996.Mn.SUB.0.004.O.SUB.9 .Prepared in Accordance with the Invention

[0097] 4 g of the phosphor having the composition K.sub.2Ge.sub.3.996Mn.sub.0.004O.sub.9 are weighed out, mixed with 1 g of an optically transparent silicone and subsequently mixed homogeneously in a planetary centrifugal mixer so that the phosphor concentration in the overall material is 80% by weight. The silicone/phosphor mixture obtained in this way is applied to the chip of a blue-emitting semiconductor LED with the aid of an automatic dispenser and cured with supply of heat. The blue LEDs used for the LED characterisation in the present example have an emission wavelength of 442 nm and are operated at a current strength of 350 mA. The photometric characterisation of the LED is carried out using an Instrument Systems CAS 140 spectrometer and an attached ISP 250 integration sphere. The LED is characterised via determination of the wavelength-dependent spectral power density. The resultant spectrum of the light emitted by the LED is used to calculate the colour point coordinates CIE x and y.

DESCRIPTION OF THE FIGURES

[0098] FIG. 1. XRD patterns with the ICCD reference for Cu K-alpha radiation

[0099] FIG. 2. Reflection spectrum of K.sub.2Ge.sub.3.996Mn.sub.0.004O.sub.9 against BaSO.sub.4 as white standard.

[0100] FIG. 3. Reflection spectrum of K.sub.2SiGe.sub.2.997Mn.sub.0.003O.sub.9 against BaSO.sub.4 as white standard.

[0101] FIG. 4. Reflection spectrum of Rb.sub.2Ge.sub.3.996Mn.sub.0.004O.sub.9 against BaSO.sub.4 as white standard.

[0102] FIG. 5. Excitation spectrum of K.sub.2Ge.sub.3.996Mn.sub.0.004O.sub.9 (.sub.em=664 nm)

[0103] FIG. 6. Excitation spectrum of K.sub.2SiGe.sub.2.997Mn.sub.0.003O.sub.9 (.sub.em=664 nm)

[0104] FIG. 7. Excitation spectrum of Rb.sub.2Ge.sub.3.996Mn.sub.0.004O.sub.9 (.sub.em=654 nm)

[0105] FIG. 8. Emission spectrum of K.sub.2Ge.sub.3.996Mn.sub.0.004O.sub.9(.sub.ex=320 nm)

[0106] FIG. 9. Emission spectrum of K.sub.2SiGe.sub.2.997Mn.sub.0.003O.sub.9 (.sub.ex=310 nm)

[0107] FIG. 10. Emission spectrum of Rb.sub.2Ge.sub.3.996Mn.sub.0.004O.sub.9 (.sub.ex=327 nm)

[0108] FIG. 11. Section from the CIE 1931 colour diagram with the colour points of K.sub.2Ge.sub.3.996Mn.sub.0.004O.sub.9, K.sub.2SiGe.sub.2.997Mn.sub.0.003O.sub.9 and Rb.sub.2Ge.sub.3.996Mn.sub.0.004O.sub.9.

[0109] FIG. 12. LED spectrum of the pc-LED described in Example e).