Synthesis and photo-luminescence properties of rare earth ion doped Li3Ba2Gd3(MoO4)8 phosphors

• Main Authors: Yee-Cheng Chang, 張翌誠
• Other Authors: Yen-Hwei Chang
• Format: Others
• Language: zh-TW
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/03947122628165768871

碩士 === 國立成功大學 === 材料科學及工程學系碩博士班 === 97 === The objet of this study is to synthesize Li3Ba2Gd3(MoO4)8 doped with various activators(Eu3+,Tb3+,Dy3+,Er3+,Sm3+), and the raw material had been mechanically activated by grinding in high energy vibromill followed by calcined at temperature of 900℃ for 12 h. By using XRD, SEM, PL spectra, and UV-visable spectra, the characterization of structure, morphology of powders and photo-luminescent properties of phosphors were analized. The dominant emission peaks of Li3Ba2Gd3(MoO4)8:Eu3+ phosphor are 5D0→7F1(591nm)、5D0 →7F2(614nm) which are originate from intra-4f transitions of excited state. The intensity of the emission from 5D0 to 7F2 is stronger than 5D0 to 7F1 and three times more than commercial phosphors, ZnS:Mn2+,Te2+ when Eu3+ concentration in x=2.4. The CIE chromaticity coordinates of red emission of the Li3Ba2Gd0.6Eu2.4(MoO4)8 phosphor is (0.67, 0.33) which is just at NTSC system standard red chromaticity. There are two regions in the excitation spectra of Li3Ba2Gd2 Tb1(MoO4)8 phosphor；one is assigned from 4f��5d transition in 200 to 300 nm, and the others are from intra-4f transitions in 350 to 500 nm. The dominant emission peak of Li3Ba2Gd2Tb1(MoO4)8 phosphor is 5D4��7F5 under excitation of 307nm. The CIE chromaticity coordinates of green emission of the Li3Ba2Gd2 Tb1(MoO4)8 phosphor is (0.25, 0.58). The the other series of green phosphor is Li3Ba2Gd2.95Er0.05(MoO4)8.Because its emission peaks locates in the light of green region, it has better color rendering index than Li3Ba2Gd2 Tb1(MoO4)8. However, the valence electrons are shielded by the 5s and 5p outer electrons, the valance electrons of trivalent rare earth ions are weakly affected by ligand ions in crystals, so the features of optical spectra of the most phosphors doped with trivalent rare earth, such as Li3Ba2Gd3(MoO4)8:Dy3+ and Li3Ba2Gd3(MoO4)8:Sm3+ is similar to those expected for free ions.