近化学计量比铌酸锂晶体的晶格振动和相变软模研究

The Study of Lattice Vibration and Phase Transition Soft Mode in Near StoichioMetric Lithium Niobate Crystals

在室温下,近化学计量比铌酸锂晶体(S-LN)的拉曼散射研究从理论和实验上揭示了晶格空位对于拉曼光谱的影响。高温下,随着温度的升高,软模(5的拉曼峰变化非常强烈。一个软光学声子模来源于在铌-氧平面内的三重简并对称弯曲振动。顺电-铁电结构相变发生在大约1170℃。

At room temperature, Raman- scattering investigations of near stoichiometric lithium niobate （S- LN） crystals theoretically and experimentally reveal an effect of the lattice vacant positions on the Raman spectra. At high temperature, Raman peaks of the mode （5 vary sensitively and intensely with the increase of the temperature. A condensed soft optical phonon mode originates from the triply degenerate symmetric in - plane O - Nb - O bending. The paraelectric-ferroelectric structural transition occurs at about 1170℃.