本實驗利用固相合成法製備不含稀土離子的螢光粉主體SrWO4，分別摻雜Pr3+以及Dy3+作為發光中心，並分別添加Na+、K+、Nb5+作為電荷補償離子，探討材料煆燒溫度、摻雜濃度、以及電荷補償後對主體晶格結構和螢光性質的影響。
　　Sr1-2x(RE,M)xWO4和Sr1-xRExW1-xNbxO4 (x=0.005~0.1; RE=Pr3+, Dy3+; M=K+, Na+)螢光粉體在1100℃的溫度下煆燒後，由XRD繞射結果證實，可形成純相的正交晶系之鎢酸鈣礦結構。從吸收光譜的結果顯示，主體晶格的能帶間隙大約在3.5eV(354nm)。
　　螢光光譜顯示摻雜Pr3+的螢光粉體，可在448nm激發光下同時發出487nm (3P0→3H4)的藍光和647nm (3P0→3F2)的紅光，其最佳發光濃度為1.0 at%，換算出的CIE色度座標落在(x=0.30, y=0.35)的白光區內。至於摻雜Dy3+的螢光粉體，可在351nm的激發光下同時發出486nm (4F9/2→6H15/2)的藍光和574nm (4F9/2→6H13/2)的黃光，其中黃光的強度比藍光強很多，換算出的CIE色度座標為(x=0.39, y=0.43)，座落在黃綠光區。最強發光的摻雜濃度為3 at%。
　　電荷補償離子對螢光強度的影響取決於不同的稀土離子。對於Pr3+而言，若以Na+或K+作為電荷補償離子，螢光強度和淬滅濃度都有下降的趨勢，而在以Nb5+離子當作電荷補償的情況下，其螢光強度會有提升。對於Dy3+而言，添加Na+或K+離子有助於螢光強度的提升，而添加Nb5+離子卻使螢光強度明顯地下降。

A series of phosphors, Sr1-2x(RE,M)xWO4 and Sr1-xRExW1-xNbxO4 (x=0.005~0.1; RE=Pr3+, Dy3+; M=K+, Na+), were synthesized by the high temperature solid-state reaction, in order to develop a novel host material, SrWO4, which does not contain any rare-earth element. The effects on the luminescent properties of the optical center density (i.e. the RE concentration) and the charge compensation by K+, Na+ and Nb5+, as well as the influences of sintering temperature on the host crystal structure, were investigated by a series of techniques.
X-ray diffraction confirmed that the phosphors sintered at 1100℃ were of a pure phase with the tetragonal Scheelite structure. The band gap of the host crystal was measured to be around 3.5 eV by the absorption spectra. For the Pr3+ doped phosphors, the photoluminescence spectra showed that under the excitation light of 448 nm, two main emissions at 487nm (blue, 3P0→3H4) and 647nm (red, 3P0→3F2) were observed. The two could be mixed to give out a white light with the CIE chromaticity coordinates located at (x=0.30, y=0.35). The optimum Pr3+ concentration was found to be 1.0 at.%. For the Dy3+ doped phosphors, a strong yellow emission at 574nm (4F9/2→6H13/2) and a weak blue emission at 486nm (4F9/2→6H15/2) were observed under the UV excitation of 351nm. The blend of the two emissions gave out a chartreuse light, corresponding to the CIE chromaticity coordinates of (x=0.39, y=0.43). The Dy3+ concentration for the maximum emission intensity was 3.0 at.%.
The effects of the charge compensation ions were dependent on the type of the optical center. For Pr3+, the addition of K+ or Na+ was actually not beneficial, causing a deduction of both the emission intensity and the optimum doping concentration, whereas the addition of Nb5+ did increase the intensity of photoluminescence. In contrast, for Dy3+, doping of K+ or Na+ increased the photoluminescence intensity while Nb5+ caused a decrease of the intensity.

1. Errandonea, D., et al., Effect of pressure on the luminescence properties of Nd3+ doped SrWO4 laser crystal. Journal of Alloys and Compounds, 2008. 451(1-2): p. 212-214.
2. Ivleva, L.I., et al., SrWO4:Nd3+ - new material for multifunctional lasers. Optical Materials, 2003. 23(1-2): p. 439-442.
3. Sulc, J., et al., Nd:SrWO4 and Nd:BaWO4 Raman lasers. Optical Materials, 2007. 30(1): p. 195-197.
4. Jia, G., et al., Optical spectroscopy of Yb3+ doped SrWO4 scheelite crystal. Journal of Alloys and Compounds, 2007. 436(1-2): p. 341-344.
5. Ju, Z., et al., Red phosphor SrWO4:Eu3+ for potential application in white LED. Optical Materials, 2011. 33(6): p. 909-913.
6. Ju, Z.-H., et al., A novel orange emissive phosphor SrWO4:Sm3+ for white light-emitting diodes. Journal of Alloys and Compounds, 2010. 507(1): p. 133-136.
7. Liao, J., et al., Hydrothermal synthesis and photoluminescence of SrWO4:Tb3+ novel green phosphor. Materials Research Bulletin, 2009. 44(9): p. 1863-1866.
8. Liao, J., et al., Synthesis process and luminescence properties of Tm3+ in AWO4 (A = Ca, Sr, Ba) blue phosphors. Journal of Alloys and Compounds, 2009. 487(1-2): p. 758-762.
9. Bao, A., et al., Luminescent properties of nanoparticles YPXV1-XO4:Dy phosphors. Journal of Luminescence, 2008. 128(1): p. 60-66.
10. Fuchs, E.C., et al., Polyspectral white light emission from Eu3+, Tb3+, Dy3+, Tm3+ co-doped GdAl3(BO3)4 phosphors obtained by combustion synthesis. Materials Science and Engineering: B, 2009. 156(1-3): p. 73-78.
11. Qi, X., et al., Pr3+ doped LaTiNbO6 as a single phosphor for white LEDs. Journal of Alloys and Compounds, 2010. 492(1-2): p. L61-L63.
12. Boutinaud, P., et al., Red luminescence induced by intervalence charge transfer in Pr3+-doped compounds. Journal of Luminescence,2007. 122-123: p. 430-433.
13. Boutinaud, P., et al., UV-to-red relaxation pathways in CaTiO3:Pr3+. Journal of Luminescence, 2005. 111(1-2): p. 69-80.
14. Boutinaud, P., et al., Making red emitting phosphors with Pr3+. Optical Materials, 2006. 28(1-2): p. 9-13.
15. Chen, J., et al., Synthesis and spectral property of Pr3+-doped tungstate deep red phosphors. Journal of Alloys and Compounds, 2010. 492(1-2): p. 667-670.
16. Yang, X., et al., The investigation of optical properties by doping halogen in the BaMoO4:Pr3+ phosphor system. Journal of Alloys and Compounds, 2009. 479(1-2): p. 307-309.
17. Liu, B., et al., White-light long-lasting phosphor Sr2MgSi2O7:Dy3+. Journal of Luminescence, 2007. 122-123: p. 121-124.
18. 徐敘瑢、蘇勉曾, 發光學與發光材料. 2004, 北京: 化學工業出版社.
19. Rao C N F R S , G.J., New Directions in Solid State Chemistry. Second Edition ed. 1998: London :Cambridge University Press.
20. Yang, J.E., The Application and Investigation of Luminescence Materials in Electronic Industry, in Technical Report of ITRI. 1992: Hsinchu, Taiwan.
21. Shinkichi, T., Luminescence centers of ns2-type ions. 1999, CRC: Boca Raton-Boston-London-New York-Washington.
22. Ogasawara, K., et al., Optical spectra of trivalent lanthanides in LiYF4 crystal. Journal of Solid State Chemistry, 2005. 178(2): p. 412-418.
23. Ropp, R.C., Luminescence and the Solid State, Second Edition. 2004, Amsterdam: Elsevier Science.
24. Kutty, T.R.N., et al., Luminescence of Eu2+ in strontium aluminates prepared by the hydrothermal method. Materials Research Bulletin, 1990. 25(11): p. 1355-1362.
25. Kingsley, J.J., et al., Combustion synthesis of fine particle rare earth orthoaluminates and yttrium aluminum garnet. Journal of Solid State Chemistry, 1990. 88(2): p. 435-442.
26. D, C.S.C.N.C.a., Phosphor global summit. 2006: in: Sylvania.
27. Sczancoski, J.C., et al., Synthesis, growth process and photoluminescence properties of SrWO4 powders. Journal of Colloid and Interface Science, 2009. 330(1): p. 227-236.
28. Jia, G., et al., Czochralski technique growth of pure and rare-earth-doped SrWO4 crystals. Journal of Crystal Growth, 2004. 273(1-2): p. 220-225.
29. Kolobanov, V.N., et al., Optical and luminescent properties of anisotropic tungstate crystals. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2002. 486(1-2): p. 496-503.