BGO∶TR(TR=Nd,Er),Cr,Fe晶体的吸收光谱和发光光谱

Absorption and Luminescence Spectra of Bi_4Ge_3O_(12)∶TR (TR=Nb,Er),Cr,Fe Single Crystals

在化学计量的Bi_2O_3(5N)和 GeO_2(6N)的配料里,加入0.01wt%Nd_2O_3,0.01wt%Er_2O_3,0.02wt%Cr_2O_3或0.02wt%Fe_2O_3,用 Bridgman 方法生长 Bi_4Ge_3O_(12)掺杂晶体。给出 eulytite 的结构投影和 BGO 晶体的点阵常数。掺杂稀土 BGO 晶体的室温吸收光谱由稀土离子所特有的几个吸收带所组成。采用3d^3电子的能量久期方程计算 O_h 场下掺 Cr^(3+)BGO 的库仑相互作用参数和内晶体场参数,其吸收光谱是由基态~4A_2到~2E,~4T_2和~4T_1跃迁的三个带组成。以300nm 激发观察到纯锗酸铋强的宽带发光,其峰值位置在498和550nm。这种发射被认为是 Bi^(3+)的~3P_1→~1S_0跃迁。由于存在大的 Stokes 迁移,Bi^(3+)系统猝灭心受到阻止。另外,由于~3P-~1S 能级差别大,使多声子过程中的非辐射衰减亦受到限制。通过接收498nm 发射波长,测量纯 BGO 室温激发光谱,其峰值位置在250、272和285nm,这和 M.J.Weber 测定的吸收收和反射光谱的结果基本一致。按不同波长范围分别采用光电倍增管和 PbS 接收,测量了 BGO 掺 Nd^(3+)的~4F_(3/2)→~4I_(11/2),~4I_(13/2)跃迁;掺 Er^(3+)的~4I_(13/2)→~4I_(15/2)跃迁的荧光光谱。强的荧光发射以及发射带宽界于 YAG和玻璃之间,表明掺杂稀土的 BGO 晶体是一类有希望的激光材料。

Cubic zirconia crystals stabilized by yttria with or without dopants were obtai-ned by skull-melting technique.The different dopant compositions were CeO_2 (0.01,0.3 and 0.5 wt%),Fe_2O_3 0.03 wt%+CeO_2 0.01 wt%,Fe_2O_3 0.03 wt%+CeO_20.03 wt%,CoO (0.1 and 0.3 wt%),Cr_2O_3 1wt% respectively.The optical ab-sorption spectra of these crystals in the range of 300-800 nm were measured with aBeckman modle UV 5270 spectrometer at room temperature.The absorption spectraof the crystals grown in air,or further irradiated by ^(60)Co -ray,were recorded.Theexperimental results show that new absorption spectrum bands will appear for suchcrystals doped with Ce or Co,because of Ce^(4+) changing into Ce^(3+),or Co^(3+) intoCo^(2+) during irradiation.For those crystals doped with Cr,there will not appear anynew absorption spectrum bands after irradiation.The luminescence spectra of the crystals doped with Cr or Er,etc.were alsomeasured and discussed.