Abstract

Reported are the results of studying the sharp increase in the spectral intensity at the lattice soft mode near the temperature of the phase transition in the lithium tantalate crystal. The Raman scattering spectra are recorded in the x(zz)y polarization geometry corresponding to manifestation of the soft mode responsible for the ferroelectric phase transition in lithium tantalate at 898 K. The recording is performed at fixed temperatures T (\(I(\omega {\kern 1pt} ',T)\), T = const) and at fixed spectrometer frequencies (\(I(\omega {\kern 1pt} ',T)\), \(\omega {\kern 1pt} ' = {{\omega }_{0}} - T = {\text{const}}\)) under slow (1 deg./min) crystal temperature variation. Strong increase (by three orders of magnitude) is observed in the peak of the reduced spectral intensity i₀(Ω) of the isofrequency temperature dependence at the fixed spectrometer frequency shift relative to the exciting radiation \(\Omega = {{\omega }_{0}} - \omega {\kern 1pt} ' = 10\) cm^–1 similar to the one earlier observed in quartz crystals.

中文翻译：

---

钽酸锂晶体中铁电相变温度附近软模拉曼散射光谱强度的反常增加

摘要

报告的结果是研究钽酸锂晶体中相变温度附近晶格软模式下光谱强度的急剧增加。拉曼散射光谱记录在x（zz）y极化几何图中，对应于在898 K下钽酸锂中负责铁电相变的软模的表现。记录在固定温度T（\（I（\ omega {\ kern 1pt}'，T）\），T = const）并在固定光谱仪频率下（\（I（\ omega {\ kern 1pt}'，T）\），\（\ omega {\ kern 1pt}' = {{\\ omega} _ {0}}-T = {\\ t​​ext {const}} \））在缓慢（1度/分钟）的晶体温度变化下。在固定频谱仪相对于激发辐射的频移下，等频率温度相关性的降低的频谱强度i ₀（Ω）的峰值中观察到强烈增加（三个数量级）的峰值\（\ Omega = {{\ omega} _ {0}}-\ omega {\ kern 1pt}'= 10 \） cm ^–1类似于前面在石英晶体中观察到的厘米。