An oxide phosphor that is highly durable and produces visible light when excited by exposure to near-ultraviolet excitation light, comprising an oxide having the composition represented by the formula (Al 2 O 3 ) x .(SiO 2 ) 1-x , where 0<x<1, and an activating element M.
1. A method comprising:
mixing a source of an activating element M with an oxide of formula (Al 2 O 3 ) x .(SiO 2 ) 1-x to form a mixture; and
sintering the mixture;
wherein:
M is Ce, Sm, Eu, Yb, or Dy;
an amount of M is 0.06 mol % relative to the total moles of Al and Si; and
x is 0.5≦x≦0.7.
2. The method of claim 1 , wherein sintering is conducted at a temperature of 1000° C. to 1800° C.
3. The method of claim 1 , wherein sintering is conducted at a temperature of 1100° C. to 1700° C.
4. The method of claim 1 , wherein sintering is conducted at a temperature of 1200° C. to 1600° C.
5. The method of claim 1 , wherein sintering is conducted from 1 to 10 hours.
6. The method of claim 1 , wherein the sintering is conducted under vacuum, in a nitrogen atmosphere, in an air atmosphere, or in a hydrogen atmosphere.
7. The method of claim 1 , wherein the oxide is prepared from a sol-gel.
8. The method of claim 1 , wherein the oxide is a mullite of formula 3Al 2 O 3 .2SiO 2 , 3Al 2 O 3 .1.75SiO 2 , or 3Al 2 O 3 .1.55SiO 2 .
9. The method of claim 1 , wherein the source of the activating element M is an oxide, hydroxide, chloride, fluoride, carbonate, sulfate, nitrate, or acetate of M.
10. The method of claim 1 , wherein the activating element is Ce or Eu.
11. The method of claim 1 further comprising preparing the oxide by mixing tetraethyl orthosilicate with aluminum nitrate and ammonium hydroxide in ethanol to form a first mixture; heating the first mixture;
removing the solvent to form an amorphous gel; and sintering the amorphous gel to provide a precursor to the oxide of formula (Al 2 O 3 ) x .(SiO 2 ) 1-x .
12. The method of claim 11 , wherein the precursor to the oxide is a mullite precursor.
13. The method of claim 1 , wherein the mixing is conducted in the presence of ethanol.
14. The method of claim 1 , wherein the source of the activating element M is Eu 2 O 3 ; Dy 2 O 3 , Yb 2 O 3 , CeO 2 , or Sm 2 O 3 .
15. A method comprising:
preparing an oxide of formula (Al 2 O 3 ) x ).(SiO 2 ) 1-x from a sol-gel and concurrently mixing the starting materials of the oxide with the source of an activating element M; and
sintering the mixture;
wherein:
M is Ce, Sm, Eu, Yb, or Dy;
an amount of M is 0.06 mol % relative to the total moles of Al and Si; and
x is 0.5≦x≦0.7.
16. The method of claim 15 , wherein the oxide is a mullite of formula 3Al 2 O 3 .2SiO 2 , 3Al 2 O 3 .1.75SiO 2 , or 3Al 2 O 3 .1.5SiO 2 .
17. The method of claim 15 , wherein the source of the activating element M is an oxide, hydroxide, chloride, fluoride, carbonate, sulfate, nitrate, or acetate of M.
18. The method of claim 15 , wherein the source of the activating element M is Eu 2 O 3 ; Dy 2 O 3 , Yb 2 O 3 , CeO 2 , or Sm 2 O 3 .
19. The method of claim 15 , wherein the oxide is prepared by mixing tetraethyl orthosilicate with aluminum nitrate and ammonium hydroxide in ethanol to form a first mixture; heating the first mixture; removing the solvent to form an amorphous gel; and sintering the amorphous gel to provide a precursor to the oxide of formula (Al 2 O 3 ) x .(SiO 2 ) 1-x .