铁电相变区附近铌酸钾锂晶体的特殊晶格振动行为

Special Vibration Behavior of KLN Crystal Lattice near Ferroelectric Phase Transition Area

通过测量一批不同组成的铌酸钾锂晶体的Raman光谱，分析其晶体中组分离子浓度对晶体红外Raman光谱特征的影响，结果表明，晶体中位于C格位的Li浓度对晶体Raman光谱产生了强烈的影响：低Li含量晶体中[NbO6]^7-八面体所对应的3个Raman特征光谱线没有峰发生分裂，在100-400cm^-1范围出现小峰与C格位Li存在相关；当晶体中Li浓度增加时，与v5所对应的Raman峰在散射几何为X（ZY）Z对应的光谱中有所加宽，v2振动模式在两种散射几何中均出现分裂峰，并在100～400cm^-1范围内出现小峰数量增多；当Li浓度接近晶体化学组成时，微扰进一步加强，v5所对应的Raman峰分裂成3个峰，v1和v2振动模式发生部分分裂，在100～400cm^-1范围内小峰更为突出。

Raman spectra of a batch of potassium lithium niobate（KLN） crystals with different compositions have been investigated. The analysis results have shown striking effects of Li content for these Raman peaks. For KLN sample with small Li content, the three character peaks belong to [NbO6]^7- octahedron show no split, and the weak peaks in the wave range of 100-400 cm^-1 are related to the Li ions in C lattice. With the raise of Li content in crystal, the peaks belong to v2 mode have been partly split, and the peak belongs to va mode has been broadened in the spectrum corresponding to scattering geometry X[ZY）Z. When the Li concentration approaches to the chemical composition KLN crystal, the peaks belong to v5 mode have been split, and the peaks belong to v1 mode and v2 mode are partly split also.