Silicate phosphors

Abstract

The present invention relates to Eu, Sm or Pr-doped silicate compounds, to a process for the preparation thereof and to the use thereof as conversion phosphors. The present invention also relates to an emission-converting material comprising at least the conversion phosphor according to the invention and to the use thereof in light sources, in particular pc-LEDs (phosphor converted light emitting devices). The present invention furthermore relates to light sources, in particular pc-LEDs, and lighting units which contain a primary light source and the emission-converting material according to the invention.

Claims

1. A compound of the formula I
(Ba.sub.ySr.sub.1y)Zr.sub.1xHf.sub.xSi.sub.3O.sub.9(I), where x is in the range from 0 to 1 and, independently thereof, y is in the range from 0 to 1, wherein some of the Zr or Hf ions have been replaced by Eu.sup.3+ ions, Sm.sup.3+ ions or Pr.sup.3+ ions, and an amount of alkali-metal ions equivalent to the Eu.sup.3+ ions, Sm.sup.3+ ions or Pr.sup.3+ ions is present for charge compensation.

2. A compound according to claim 1, wherein 0.1 to 20 mol % of the Zr or Hf ions have been replaced by Eu, Pr or Sm ions.

3. A compound according to claim 2, wherein 0.2 to 10 mol %, of the Zr or Hf ions have been replaced by Eu, Pr or Sm ions.

4. A compound according to claim 1, wherein x is equal to 0 or 1.

5. A Compound according to claim 1, wherein 0y<0.3.

6. A compound according to claim 5, wherein y =0.

7. A compound according to claim 5, wherein 0.7<y 1.

8. A compound according to claim 5, wherein y=1.

9. A process for the preparation of a compound according to claim 1, comprising: a) providing a barium and/or strontium source, a zirconium or hafnium source, a silicon source and a source of one of on of the metals samarium, praseodymium or europium; b) mixing of the sources provided in step a); and c) temperature treatment of the sources mixed in step b) in the range from 1000 to 1700 C.

10. An emission-converting material comprising a compound according to claim 1.

11. An emission-converting material according to claim 10, which additionally comprises at least one further conversion phosphor.

12. An emission-converting material according to claim 11, where the further conversion phosphor is a sulfide, a silicate, an aluminate, a borate, a nitride, an oxynitride, a siliconitride or a alumosiliconitride and said conversion phosphor is doped with Eu.sup.2+, Ce.sup.3+ or Mn.sup.2+.

13. A light source comprising a primary light source and an emission-converting material according to claim 10.

14. A light source according to claim 13, wherein the primary light source is a luminescent indium aluminium gallium nitride.

15. A lighting unit, comprising at least one light source according to claim 13.

16. A display device comprising at least one lighting unit according to claim 13.

17. A liquid-crystal display device (LC display) comprising at least one lighting unit according to claim 15.

18. A backlighting of display devices, comprising at least one light source according to claim 13.

Description

DESCRIPTION OF THE FIGURES

(1) FIG. 1: CIE 1931 colour diagram with the colour values of BaZrSi.sub.3O.sub.9:Eu.sup.2+ and BaHfSi.sub.3O.sub.9:Eu.sup.2+ and of (Sr,Ca).sub.2SiO.sub.4:Eu as orange emitter.

(2) FIG. 2: X-ray powder diffraction patterns of BaZrSi.sub.3O.sub.9:Eu.sup.2+ with 2 mol % and 0.5 mol % europium doping compared with undoped BaZrSi.sub.3O.sub.9 (measured using Cu Kai radiation).

(3) FIG. 3: Emission spectra of BaZrSi.sub.3O.sub.9:Eu.sup.2+ (.sub.ex=380 nm) with 2 mol % and 0.5 mol % europium doping.

(4) FIG. 4: X-ray powder diffraction patterns of BaHfSi.sub.3O.sub.9:Eu.sup.2+ with 2 mol %

(5) and 0.5 mol % europium doping compared with undoped BaHfSi.sub.3O.sub.9 (measured using Cu Kai radiation).

(6) FIG. 5: Emission spectra of BaHfSi.sub.3O.sub.9:Eu.sup.2+ (.sub.ex=380 nm) with 2 mol % and 0.5 mol % europium doping.

(7) FIG. 6: Emission spectra of BaZrSi.sub.3O.sub.9:Sm.sup.3+,Na.sup.+ and BaHfSi.sub.3O.sub.9:Sm.sup.3+,Na.sup.+ (.sub.ex=160 nm); in each case with 1 mol % doping.

(8) FIG. 7: Emission spectra of BaZrSi.sub.3O.sub.9:Eu.sup.3+,Na.sup.+ and BaHfSi.sub.3O.sub.9:Eu.sup.3+,Na.sup.+ (.sub.ex=160 nm); in each case with 1 mol % doping.

(9) FIG. 8: Emission spectra of BaZrSi.sub.3O.sub.9:Pr.sup.3+,Na.sup.+ and BaHfSi.sub.3O.sub.9:Pr.sup.3+,Na.sup.+ (.sub.ex=160 nm); in each case with 0.5 mol % doping.

EXAMPLES

Example 1

Preparation of BaZrSi3O9: 0.5 mol % of Eu2+

(10) 1.7191 g (8.71 mmol) of BaCO.sub.3, 1.0788 g (8.75 mmol) of ZrO.sub.2, 1.5781 g (26.26 mmol) of SiO.sub.2, 0.0077 g (0.022 mmol) of Eu.sub.2O.sub.3 and 0.1200 g (1.94 mmol) of H.sub.3BO.sub.3 are mixed thoroughly in an agate mortar with addition of a small amount of acetone as grinding agent. The powder is dried at 100 C. for 1 h, transferred into an aluminium oxide crucible and sintered at a temperature in the range from 1300 to 1500 C. for 2 to 4 h under a carbon monoxide atmosphere. In a second sintering step in a horizontal tubular furnace, the powder is subjected to a temperature of 1200 C. for 2 h under a stream of forming gas (10% of H.sub.2). FIG. 2 shows the X-ray powder diffraction pattern of the compound prepared in this way.

Example 2

Preparation of BaZrSi3O9: 2 mol % of Eu2+

(11) This compound is prepared in the same way as the compound in Example 1, with the difference that the following compounds are weighed out at the beginning and then mixed: 1.6924 g (8.58 mmol) of BaCO.sub.3, 1.0783 g (8.75 mmol) of ZrO.sub.2, 1.5774 g (26.25 mmol) of SiO.sub.2, 0.0308 g (0.088 mmol) of Eu.sub.2O.sub.3 and 0.1200 g (1.94 mmol) of H.sub.3BO.sub.3. The X-ray powder diffraction pattern of this compound is likewise shown in FIG. 2.

(12) FIG. 3 shows the emission spectra of the compounds prepared in Example 1 and Example 2.

Example 3

Preparation of BaHfSi3O9: 0.5 mol % of Eu2+

(13) This compound is prepared in the same manner as in Example 1, with the difference that the following constituents are mixed: 1.4434 g (7.31 mmol) of BaCO.sub.3, 1.5473 g (7.35 mmol) of HfO.sub.2, 1.3250 g (22.1 mmol) of SiO.sub.2, 0.0065 g (0.018 mmol) of Eu.sub.2O.sub.3 and 1.1200 g (1.94 mmol) of H.sub.3BO.sub.3. The X-ray powder diffraction pattern of this compound is shown in FIG. 4.

Example 4

Preparation of BaHfSi3O9: 2 mol % of Eu2+

(14) This compound is likewise prepared like the compound in Example 1, with the difference that the following constituents are mixed with one another: 1.4211 g (7.20 mmol) of BaCO.sub.3, 1.5467 g (7.35 mmol) of HfO.sub.2, 1.3245 g (22.0 mmol) of SiO.sub.2, 0.0259 g (0.074 mmol) of Eu.sub.2O.sub.3 and 0.1200 g (1.94 mmol) of H.sub.3BO.sub.3. The X-ray powder diffraction pattern of this compound is likewise shown in FIG. 4.

(15) FIG. 5 shows the emission spectra of the compounds prepared in Examples 3 and 4.

Example 5

Preparation of BaZrSi3O9: 1 mol % of Sm3+, 1 mol % of Na+

(16) 1.6972 g (8.60 mmol) of BaCO.sub.3, 1.0814 g (8.78 mmol) of ZrO.sub.2, 1.5819 g (26.33 mmol) of SiO.sub.2, 0.0153 g (0.044 mmol) of Sm.sub.2O.sub.3, 0.0047 g (0.044 mmol) of Na.sub.2CO.sub.3 and 0.1200 g (1.94 mmol) of H.sub.3BO.sub.3 are carefully mixed with one another in an agate mortar with addition of a small amount of acetone as grinding agent. The powder is dried at 100 C. for 1 h, transferred into an aluminium oxide crucible and sintered at 1300 to 1500 C. for 2-4 h in air.

Example 6

Preparation of BaHfSi3O9: 1 mol % of Sm3+, 1 mol % of Na+

(17) This compound is prepared in the same way as in Example 5, with the difference that the following starting materials are mixed with one another: 1.4245 g (7.22 mmol) of BaCO.sub.3, 1.5504 g (7.37 mmol) of HfO.sub.2, 1.3277 g (22.10 mmol) of SiO.sub.2, 0.0128 g (0.037 mmol) of Sm.sub.2O.sub.3, 0.0039 g (0.037 mmol) of Na.sub.2CO.sub.3 and 0.1200 g (1.94 mmol) of H.sub.3BO.sub.3.

(18) FIG. 6 shows the emission spectra of the compounds prepared in Examples 5 and 6.

Example 7

Preparation of BaZrSi3O9: 1 mol % of Eu3+, 1 mol % of Na+

(19) This compound is likewise prepared like the compound in Example 5, with the difference that the following starting compounds are mixed with one another: 1.6971 g (8.60 mmol) of BaCO.sub.3, 1.0814 g (8.78 mmol) of ZrO.sub.2, 1.5818 g (26.33 mmol) of SiO.sub.2, 0.0154 g (0.044 mmol) of Eu.sub.2O.sub.3, 0.0047 g (0.044 mmol) of Na.sub.2CO.sub.3 and 0.1200 g (1.94 mmol) of H.sub.3BO.sub.3.

Example 8

Preparation of BaHfSi3O9: 1 mol % of Eu3+, 1 mol % of Na+

(20) This compound is prepared in the same way as the compound under Example 5, with the difference that the following starting compounds are mixed with one another: 1.4244 g (7.22 mmol) of BaCO.sub.3, 1.5504 g (7.37 mmol) of HfO.sub.2, 1.3277 g (22.10 mmol) of SiO.sub.2, 0.0130 g (0.037 mmol) of Eu.sub.2O.sub.3, 0.0039 g (0.037 mmol) of Na.sub.2CO.sub.3 and 0.1200 g (1.94 mmol) of H.sub.3BO.sub.3.

(21) FIG. 7 shows the emission spectra of the compounds prepared in Examples 7 and 8.

Example 9

Preparation of BaZrSi3O9: 0.5 mol % of Pr3+, 0.5 mol % of Na+

(22) This compound is likewise prepared like the compound in Example 5, with the difference that the following starting compounds are mixed with one another: 1.7128 g (8.68 mmol) of BaCO.sub.3, 1.0803 g (8.78 mmol) of ZrO.sub.2, 1.5803 g (26.30 mmol) of SiO.sub.2, 0.0159 g (0.022 mmol) of Pr.sub.2(C.sub.2O.sub.4).sub.3. 10 H.sub.2O, 0.0023 g (0.022 mmol) of Na.sub.2CO.sub.3 and 0.1200 g (1.94 mmol) of H.sub.3BO.sub.3.

Example 10

Preparation of BaHfSi3O9: 0.5 mol % of Pr3+, 0.5 mol % of Na+

(23) This compound is prepared in the same way as the compound in Example 5, with the difference that the following starting compounds are mixed with one another: 1.4378 g (7.29 mmol) of BaCO.sub.3, 1.5491 g (7.36 mmol) of HfO.sub.2, 1.3266 g (22.08 mmol) of SiO.sub.2, 0.0134 g (0.018 mmol) of Pr.sub.2(C.sub.2O.sub.4).sub.3.10 H.sub.2O, 0.0020 g (0.018 mmol) Na.sub.2CO.sub.3 and 1.1200 g (1.94 mmol) of H.sub.3BO.sub.3.

(24) FIG. 8 shows the emission spectra of the compounds prepared in Examples 9 and 10.

Example 11

Production of a pc-LED Using Compounds According to the Invention

(25) 1 g of a phosphor according to the invention from Examples 1 to 10 is dispersed with 10 g of an optically transparent silicone (OE 6550 from Dow Corning) in a Speedmixer. The silicone/phosphor mixture obtained in this way is applied to the chip of a blue semiconductor LED (Unicorn package from Mimaki Electronics, fitted with an InGaN chip emitting at 450 nm) with the aid of an automatic dispenser (CDS 6200 from Essemtech) and cured over the course of 1 h with supply of heat in a heating cabinet at 150 C.

Example 12

Test Results of the pc-LEDs Produced in Example 11

(26) The LED from Example 11 is contacted with current (350 mA) using a Keithley K2400 Sourcemeter, and the optical properties are determined using an Instrument Systems CAS 140 spectrometer, fitted with an integration sphere. The spectrometer software calculates the CIE 1931 x and y colour points of the LED from the emission spectrum obtained here. The corresponding values are plotted in the CIE diagram in FIG. 1.