【摘要】 在化学计量的Bi₂O₃（5N）和 GeO₂（6N）的配料里,加入0.01wt%Nd₂O₃,0.01wt%Er₂O₃,0.02wt%Cr₂O₃或0.02wt%Fe₂O₃,用 Bridgman 方法生长 Bi₄Ge₃O₁₂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3d³电子的能量久期方程计算 O_h 场下掺 Cr³⁺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⁴A₂到²E,⁴T₂和⁴T₁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 Bi³⁺的³P₁→¹S₀跃迁。由于存在大的 Stokes 迁移,Bi³⁺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 Nd³⁺的⁴F_3/2→⁴I_11/2,⁴I_13/2跃迁;掺 Er³⁺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。更多还原

【Abstract】 Single crystals of bismuth germanate,Bi₄Ge₃O₁₂∶Nd（abbr.BGO∶Nd,violetishcrystal）,BGO∶Er（reddish）,BGO∶Cr（green）,BGOFe∶（brown）,were grown bythe Bridgman technique, using stoichiometric amounts of Bi₂O₃ （5N） and GeO₂（6N）,with 0.01wt% Nd₂O₃,0.01wt% Er₂O₃,0.02wt% Cr₂O₃,0.02wt% Fe₂O₃dopants respectively.The projection of the structure of eulytite and the cell parp-meter of BGO are given.The absorption spectra measured from BGO crystals dopedwith different rate earth ions show that they consist of several bands which arethe characteristic of the rare earth ions in the crystals.The magnitutes of the para-meters of Coulomb interaction and internal crystal field for BGO∶Cr under O_hcrystal-field were calculated by the secular equations of 3 d³ electrons.The absorp-tion spectrum of Cr³⁺ ions in BGO consists of three bands transited from the grou-nd state ⁴A₂ to ²E,⁴T₂ and ⁴T₁ states.Luminescence in bismuth germanate hasbeen observed.Excited by the radiation of light of 300 nm,Bi³⁺ shows a intensebroad band emission peaked at about 498 and 550 nm.The emission is assignedto ³p₁→¹S₀ transition of Bi³⁺.The quenching centers of Bi³⁺ system are impededby the large Stokes shift,and the nonradiative decay in multiphonon processes islimited for the large ³p-¹S energy difference.Having three peaks at 250,272 and285nm,the excitation spectra of pure BGO at room temperature were also measuredthrough detecting its emission wavelength excited by 498nm light.The measuredresults coinside with the absorption and reflection spectra measured by M.J.We-ber.The fluorescence spectra(corresponding to the ⁴F_3/2→⁴I_11/2 transition for Nd³⁺;⁴I_13/2→⁴I_15/2 for Er³⁺) were measured with a spectrophotomter excited by CuSO₄filtered radiation form Xenon lamp and detected by photomultiplies and PbS respo-nse depending on the spectral region.The intensity of fluorescent emission and thewidth of emission bands are intermediate to that of YAG and glasses,which showsthat rare earth-doped bismuth germanate crystal would be a promising materialfor medium-gain lasers.更多还原