LiTaO_3的高温拉曼光谱研究

High Temperature Raman Spectrum Study of LiTaO_3

利用显微共聚焦拉曼光谱技术研究了LiTaO3晶体在298～948K温度范围内的拉曼光谱,通过对其高波数拉曼峰的分析,研究了LiTaO3的相变机制。研究发现,除466.7cm-1峰外,LiTaO3的其余拉曼峰随着温度的升高向低波数方向明显频移;所有拉曼峰的半高宽随着温度的升高逐渐增加,同时拉曼峰的强度逐渐减弱;在933K附近,LiTaO3的三个拉曼峰的消失,表明LiTaO3发生了从低温铁电相到高温顺电相的相变;与此同时,在该温度附近,359.5,385.0以及466.7cm-1峰的半高宽存在超线性增加。研究结果表明,LiTaO3从低温铁电相到高温顺电相的相变是一种混合型相变,其相变过程可逆。

The high temperature Raman spectrum of LiTaO3 was studied from 298 to 948 K by microconfocal Raman technique and the mechanism of phase transition from ferroeleetric phase to paraelectric phase was studied by analyzing the high wave num- ber Raman peaks of LiTaO3. The experimental results show that all the Raman peaks except 466.7 cm 1 have a remarkable Raman shift to low frequency when increasing temperature. The full width at half maximum （FWHM） of all Raman peaks in- creases with increasing temperature, but the intensity weakens. At about 933 K, the phase transition is observed since the three Raman peaks disappear. And at about this temperature, the FWHM of 359.5, 385.0 and 466.7 cm-1 shows an obviously superlinear increasing. From the experimental results, we conclude that the phase transition is a mixed phase transition, and the phase transition is reversible.