近化学计量比钽酸锂晶体的拉曼光谱研究

Study on Raman Spectrum of Near-stoichiometry Lithium Tantalate

本文研究了不同组分钽酸锂晶体的拉曼散射光谱,我们发现,在谱线的形状和数量方面,近化学计量比晶体与同成分晶体存在明显差异。通过实验,我们得到了钽酸锂晶体完整的长波长光学模式,并首次给出了钽酸锂晶体拉曼线宽和晶体组分的定量关系。另外,我们还发现了两个与本征缺陷相关的局域模,278 cm-1和750 cm-1峰,它们的强度与晶体中本征缺陷的数量成正比。

The Raman scattering spectra of lithium tantalate crystals with different compositions were investigated. The comparison of the Raman data obtained for the congruent and the near-stoichiometric crystals reveals some differences in the shape and the number of Raman peaks, which lead to a new assignment of the long-wavelength optical phonons. And quantitative relationships between the linewidth of Raman peaks （ 142cm^ - 1 for E-phonon and 861 cm ^- 1 for A1 -phonon ） and the crystal composition were firstly presented. Two local Raman lines, 278cm^-1 and 750cm^-1, were found for the congruent crystals and attributed to the intrinsic defects, Li vacancy and anti-site Ta ion, respectively.