Silicate phosphors
The invention relates to compounds of the general formula (I) EA2-xEuxSiO4.aM2B4O7 (I) where EA stands for two or more elements selected from Ca, Sr, Zn and Ba, M stands for Li, Na or K, and a stands for a value from the range 0.01≦a≦0.08, and x stands for a value from the range 0.01≦x≦0.25.
1. A compound of formula I
EA 2-x Eu x SiO 4 . a M 2 B 4 O 7 (I)
where
EA stands for two or more elements selected from the group consisting of Ca, Sr, Zn and Ba,
M stands for Li, Na or K, and
a stands for a value from the range 0.01≦a≦0.08, and
x stands for a value from the range 0.01≦x≦0.25.
2. A compound according to claim 1 , wherein x stands for a value from the range 0.03≦x≦0.20.
3. A compound according to claim 1 , wherein a stands for a value from the range 0.01≦a≦0.05.
4. A compound according to claim 1 , wherein x stands for a value from the range 0.04≦x≦0.13.
5. A process for preparing a compound according to claim 1 , comprising
a) providing an M 2 B 4 O 7 -containing solution, which is solution A, where M=Li, Na or K,
b) providing a phosphor of the composition EA 2-x Eu x SiO 4 , which is phosphor B, where EA stands for two or more elements selected from the group consisting of Ca, Sr, Zn and Ba, and x stands for a value from the range 0.01≦x≦0.25,
c) adding and intimately mixing phosphor B with solution A,
d) washing, and
e) subsequent drying.
6. A mixture comprising at least one compound according to claim 1 and at least one further phosphor.
7. A mixture according to claim 6 , wherein the at least one further phosphor is at least one red-emitting phosphor which is an Eu-doped sulfoselenide, Eu- and/or Ce-doped nitride, oxynitride, alumosiliconitride and/or Mn(IV)-doped oxide and/or fluoride.
8. A light source, comprising a semiconductor and at least one compound according to claim 1 .
9. A light source according to claim 8 , wherein the semiconductor is a luminescent indium aluminium gallium nitride.
10. A light source according to claim 8 , wherein the semiconductor is a luminescent indium aluminium gallium nitride of formula In i Ga j Al k N, where 0≦i, 0≦j, 0k, and I+j+k=1.
11. A lighting unit, comprising at least one light source according to claim 8 .
12. A lighting unit according to claim 11 , which is suitable for the backlighting of a display device.
13. A display device, containing at least one lighting unit according to claim 11 .
14. A liquid-crystal display device, comprising at least one lighting unit according to claim 11 .
15. A method for partial or complete conversion of the blue or near-UV emission from a luminescent diode, or in an electroluminescent material, or in an electroluminescent film comprising achieving said conversion by a compound of claim 1 as a conversion phosphor.
16. A method for the backlighting of a display device, comprising backlighting said device by a lighting unit according to claim 11 .