Long persistent phosphors and persistent energy transfer technique

• US 6,953,536 B2
• Filed: 02/25/2003
• Issued: 10/11/2005
• Est. Priority Date: 02/25/2003
• Status: Active Grant

• Current Assignee: The University of Georgia Research Foundation, Inc.
• Original Assignee: The University of Georgia Research Foundation, Inc.
• Inventors: Jia, Weiyi, Jia, Dongdong, Yen, William M., Wang, Xiao-jun
• Primary Examiner(s): Koslow, C. Melissa
• Application Number:
  US10/374,696
• Publication Number:
  US 20040164277A1
• Time in Patent Office: 959 Days
• Field of Search: 252/301.4 R, 252/301.4 F
• US Class Current: 252/301.40F
• CPC Class Codes: C04B 2235/3208 Calcium oxide or oxide-forming salts thereof, e.g. lime
• CPC Class Codes: C04B 2235/3213 Strontium oxides or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/3225 Yttrium oxide or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/3229 Cerium oxides or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/3262 Manganese oxides, manganates, rhenium oxides or oxide-forming salts thereof, e.g. MnO
• CPC Class Codes: C04B 2235/6582 Hydrogen containing atmosphere
• CPC Class Codes: C04B 35/195 Alkaline earth aluminosilicates, e.g. cordierite or anorthite
• CPC Class Codes: C04B 35/20 rich in magnesium oxide , e.g. forsterite C04B35/195 takes precedence
• CPC Class Codes: C04B 35/44 based on aluminates
• CPC Class Codes: C09K 11/7721 Aluminates
• CPC Class Codes: C09K 11/77214 Aluminosilicates
• CPC Class Codes: C09K 11/7774 Aluminates
• CPC Class Codes: C09K 11/77922 Silicates
• CPC Class Codes: C30B 13/00 Single-crystal growth by zone-melting; Refining by zone-melting C30B17/00 takes precedence; by changing the cross-section of the treated solid C30B15/00; under a protective fluid C30B27/00; for the growth of homogeneous polycrystalline material with defined structure C30B28/00
• CPC Class Codes: C30B 29/20 Aluminium oxides
• CPC Class Codes: C30B 29/22 Complex oxides
• CPC Class Codes: C30B 29/34 Silicates
• CPC Class Codes: C30B 29/66 Crystals of complex geometrical shape, e.g. tubes, cylinders

Abstract

The invention provides long-persistent phosphors, methods for their manufacture and phosphorescent articles. The invention also provides a method for generating a long-persistent phosphorescence at a selected color. The phosphors of the invention may be alkaline earth aluminates, alkaline earth silicates, and alkaline earth aluminosilicates. The phosphors include those activated by cerium. The phosphors also include those in which persistent energy transfer occurs from a donor ion to an acceptor ion, producing persistent emission largely characteristic of the acceptor ion.

Claims

1. A method for generating long persistent phosphorescence at a selected color comprising the steps of:

a) selecting at least a first activator capable of producing long persistent phosphorescence of a first color when incorporated with a co-activator into a host;

b) selecting at least a second activator capable of producing long persistent phosphorescence of the selected color when incorporated into the host with the first activator and the co-activator, the second activator being capable of accepting energy from the first activator;

c) fabricating a long-persistent phosphor comprising the second activator, the first activator and the co activator incorporated into the host; and

d) irradiating the long-persistent phosphor, thereby producing long-persistent phosphorescence of the selected color,

wherein the first activator, the second activator, and the co-activator are all different ions and the first color is different from the selected color and the host is an alkaline-earth aluminate or an alkaline-earth aluminosilicate.

2. The method of claim 1 wherein the second color is green, yellow, orange or red.

3. The method of claim 1 wherein the second activator is selected from the group consisting of Pr³⁺, Nd³⁺, Eu³⁺, Tb³⁺,Er³⁺, Tm³⁺, Ti²⁺, Cr³⁺, Mn²⁺, Ni²⁺, Pb⁺, and Bi³⁺.

4. The method of claim 1 wherein the first activator is selected from the group consisting of Ce³⁺, Pr³⁺, Sm³⁺, Eu²⁺, Dy³⁺, and Yb³⁺.

5. A method for making a long persistent phosphor comprising the steps of:

a) combining the phosphor components according to the stoichiometry of the formula;

v(MO).(x/2) (Al₂O₃).y(SiO₂);

dD, cC, aA

where M is an alkaline-earth metal, D is a donor ion, C is a co activator ion, A is an acceptor ion, v>

0, x≧

0, y≧

0, x+y>

0, 0<

d≦

10%, 0<

c≦

10% and 0<

a≦

10%; and

b) sintering the phosphor components; and

c) growing a single crystal from the sintered phosphor components, whereby the phosphor is a single crystal phosphor.

6. The method of claim 5 wherein a flux is combined with the phosphor components in step (a).

7. The method of claim 5 wherein the flux is B₂O₃, H₃BO₃, or hydrates thereof.

8. The method of claim 5 wherein D is selected from the group consisting of Ce³⁺, Pr³⁺, Sm³⁺, Eu²⁺, Dy³⁺, and Yb³⁺ and A is selected from the group consisting of Pr³⁺, Nd³⁺, Eu³⁺, Tb³⁺, Er³⁺, Tm³⁺, Ti²⁺, Cr³⁺, Mn²⁺, Ni²⁺, Pb⁺, and Bi³⁺.

9. A method for making a long persistent phosphor comprising the steps of:

a) combining the phosphor components according to the stoichiometry of the formula;

v(MO).(x/2) (Al₂O₃).y(SiO₂);

dD, cC, aA

where M is an alkaline-earth metal, D is a donor ion, C is a co activator ion, A is an acceptor ion, v>

0, x≧

0, y≧

0, x+y>

0, 0<

d≦

10%, 0<

c≦

10% and 0<

a≦

10%;

b) sintering the phosphor components; and

c) grinding the sintered phosphor components and re-sintering the ground phosphor components in a reducing or oxidizing atmosphere.

10. A method for making a long persistent phosphor comprising the steps of:

a) combining the phosphor components according to the stoichiometry of the formula;

v(MO).(x/2) (Al₂O₃).y(SiO₂);

dD, cC, aA

where M is an alkaline-earth metal, D is a donor ion, C is a co activator ion, A is an acceptor ion, x+y>

0, 0<

d≦

10%, 0<

c≦

10% and 0<

a≦

10%; and

b) sintering the phosphor components, wherein v is 1, x is 2, and y is 0, or wherein v is 2, x is 2, and y is 1.

11. A long persistent phosphor comprising an alkaline-earth metal aluminate or an alkaline-earth metal aluminosilicate host, a donor ion, a co-activator, and an acceptor ion, wherein the donor ion is capable of transfer of optical energy to the acceptor ion, the phosphor emits light largely characteristic of the acceptor ion and the first activator, the second activator, and the co-activator are all different ions.

12. The phosphor of claim 11 wherein the donor ion is selected from the group consisting of Ce³⁺, Pr³⁺, Sm³⁺, Eu²⁺, Dy³⁺, and Yb³⁺.

13. The phosphor of claim 11 wherein the acceptor ion is selected from the group consisting of Pr³⁺, Nd³⁺, Eu³⁺, Tb³⁺, Er³⁺, Tm³⁺, Ti²⁺, Cr³⁺, Mn²⁺, Ni²⁺, Pb⁺, and Bi³⁺.

14. A long persistent phosphor represented by the formula:

M_vAl_xSi_yO_z;

dD, cC, aA

wherein M is an alkaline earth metal, D is a donor ion, A is an acceptor ion, C is a co activator ion v>

0, x>

0, y≧

0, x+y>

0, z>

0, 0<

d≦

10%, 0<

c≦

10% and 0<

a≦

10% and the phosphor emits light largely characteristic of the acceptor ion.

15. The phosphor of claim 14, wherein M is selected from the group consisting of Mg, Ca, Sr, and Ba.

16. The phosphor of claim 14, wherein 0.5%<

d≦

2%, and 0.5<

a≦

2% and 0<

c≦

5%.

17. The phosphor of claim 14 wherein the phosphor is a powder, a ceramic body or a single crystal.

18. The phosphor of claim 14 wherein v is 1, x is 2, y is 0, and z is 4.

19. The phosphor of claim 18 wherein D is selected from the group consisting of Ce³⁺, Pr³⁺, Sm³⁺, Eu²⁺, Dy³⁺, and Yb³⁺ and A is selected from the group consisting of Pr³⁺, Nd³⁺, Eu³⁺, Tb³⁺, Er³⁺, Tm³⁺, Ti²⁺, Cr⁺, Mn²⁺, Ni²⁺, Pb⁺, and Bi³⁺.

20. The phosphor of claim 14 wherein v is 2, x is 2, y is 1, and z is 7.

21. The phosphor of claim 20 wherein D is selected from the group consisting of Ce³⁺, Pr³⁺, Sm³⁺, Eu²⁺, Dy³⁺, and Yb³⁺ and A is selected from the group consisting of Pr³⁺, Nd³⁺, Eu³⁺, Tb³⁺, Er³⁺, Tm³⁺, Ti²⁺, Cr³⁺, Mn²⁺, Ni²⁺, Pb⁺, and Bi³⁺.

23. A phosphorescent article comprising the phosphor of claim 14 embedded in a matrix which does not substantially react with the phosphor.

24. A method for generating long persistent phosphorescence comprising the steps of:

a) providing a phosphor of claim 14; and

b) irradiating the phosphor such that long persistent phosphorescence is produced.

22. A long persistent phosphor represented by the formula:

M_vAl_xSi_yO_z;

dD, cC, aA

wherein M is an alkaline earth metal, D is a donor ion, A is an acceptor ion, C is a co activator ion v>

0, x≧

0, y≧

0, x+y>

0, z>

0, 0<

d≦

10%, 0<

c≦

10% and 0<

a≦

10% and the phosphor emits light largely characteristic of the acceptor ion, wherein the phosphor is a ceramic body or a single crystal.

25. A composition of the formula:

MSiO₃;

dD, cC, aA

wherein M is an alkaline-earth metal, D is a donor ion, A is an acceptor ion, C is a co activator ion, 0<

d≦

10%, 0≦

c≦

10% and 0<

a≦

10%.

26. The phosphor of claim 25 wherein D is selected from the group consisting of Ce³⁺, Pr³⁺, Sm³⁺, Eu²⁺, Dy³⁺, and Yb³⁺ and A is selected from the group consisting of Pr³⁺, Nd³⁺, Eu³⁺, Tb³⁺, Er³⁺, Tm³⁺, Ti²⁺, Cr³⁺, Mn²⁺, Ni²⁺, Pb⁺, and Bi³⁺.

27. A composition of the formula:

MAl₂O₄;

dCe, aMn

wherein M is on alkaline earth metal, 0<

d≦

10% and 0<

a≦

10%.

28. A composition of the formula:

M₂Al₂SiO₇;

dCe, aMn

wherein M is an alkaline earth metal, 0<

d≦

10% and 0<

a≦

10%.

29. A composition of the formula:

MSiO₃;

dEu, aMn, cDy

wherein M is an alkaline earth metal, 0<

d≦

10%, 0<

a≦

10% and 0≦

c≦

10%.

30. The phosphor of claim 29 wherein M is magnesium.

31. A method for making a long persistent phosphor comprising the steps of:

a) combining the phosphor components according to the stoichiometry of the formula;

v(MO).(x/2) (Al₂O₃).y(SiO₂);

dD, cC, aA

where M is an alkaline-earth metal, D is a donor ion, C is a co activator ion, A is an acceptor ion, v and y are 1, x is 0, 0<

d≦

10%, 0<

c≦

10% and 0<

a≦

10%; and

b) sintering the phosphor components.

32. A long persistent phosphor represented by the formula:

M_vAl_xSi_yO_z;

dD, cC, aA

wherein M is an alkaline earth metal, D is Ce³⁺, A is Mn²⁺, and C is a co activator ion, v is 1, x is 2, y is 0, z>

0, 0<

d≦

10%, 0≦

c≦

10% and 0<

a≦

10% and the phosphor emits light largely characteristic of the acceptor ion.

33. A phosphor composition comprising an alkaline-earth aluminate or an alkaline-earth aluminosilicate host doped with a donor, co-activator, and an acceptor, wherein the donor ion persistently transfers absorbed energy to a trap center formed by the co-activator and the trap center persistently transfers energy to the acceptor causing the acceptor to persistently emit.

34. A long persistent phosphor composition comprising an alkaline-earth aluminate or an alkaline-earth aluminosilicate host doped with a plurality of ions, wherein the phosphor composition has a peak emission wavelength of about 585 nm or more.

35. A long persistent phosphor represented by the formula:

MAl₂SiO₇;

dD, cC, aA

wherein M is an alkaline earth metal, D is a donor ion, A is an acceptor ion, C is a co-activator ion, 0<

d≦

10%, 0<

c≦

10% and 0<

a≦

10% and the phosphor emits light largely characteristic of the acceptor ion.

36. The phosphor of claim 35 wherein D is Ce³⁺ and A is Mn²⁺.