Phosphor for a UV emitting device and a UV generating device utilizing such a phosphor
The invention relates to a phosphor for a UV emitting device, having the formula Na 1+x Ca 1−2x PO 4 :PR3 + x wherein 0<x<0.5.
1. A phosphor for a UV emitting device, having the formula
Na 1+x Ca 1−2x PO 4 :PR 3+ x ,
wherein
0.01<x<0.1, and
wherein the phosphor is configured to convert vacuum ultraviolet (VUV) radiation to UV-C radiation.
2. The phosphor of claim 1 , wherein the value of x is 0.03<x<0.07.
3. A phosphor according to claim 1 , characterized in that the value of x is 0.04<x<0.06.
4. The phosphor of claim 1 , wherein the phosphor is essentially free of Yttrium.
5. A UV generating device comprising a phosphor according to claim 1 and a UV radiation source.
6. The phosphor according to claim 1 , wherein the phosphor is excited by a light having a wavelength of 172 nm and 185 nm to emit an ultraviolet light in the range of 230 nm to 260 nm.
7. A method comprising:
providing a phosphor having the formula: Na 1+x Ca 1−2x PO 4 :PR 3+ x , wherein 0<x<0.5;
exposing the phosphor to VUV radiation; and
converting the VUV radiation to UV-C radiation using the phosphor.
8. The method of claim 7 , further comprising placing the phosphor inside a gas discharge lamp.
9. The method according to claim 7 , further comprising exposing water or wastewater to the UV-C radiation emitted by the phosphor.
10. A UV generating device comprising:
a phosphor having the formula Na 1+x Ca 1−2x PO 4 :PR 3+ x , wherein 0<x<0.5, and
a UV radiation source comprising a gas discharge lamp.
11. The UV generating device according to claim 10 , wherein the UV radiation source comprises a low pressure mercury gas discharge lamp.
12. The UV generating device according to claim 10 , wherein the UV radiation source comprises a low pressure mercury amalgam gas discharge lamp.
13. The UV generating device according to claim 10 , wherein the UV radiation source comprises an excimer lamp.
14. The UV generating device according to claim 13 , wherein the UV radiation source comprises an excimer gas discharge lamp with a gas filling that predominately emits a second Xenon excimer continuum.
15. The UV generating device according to claim 13 , wherein the UV radiation source comprises an excimer gas discharge lamp with a gas filling that is essentially free of mercury.
16. The UV generating device according to claim 14 , wherein the gas filling contains more than 50% by volume of Xenon.
17. The UV generating device according to claim 14 , wherein upon excitation the phosphor emits an ultraviolet light in the range of 230 nm to 260 nm.