铁电晶体铌酸钾锂的拉曼和FT-IR光谱

RAMAN AND FT-IR SPECTRA OF FERROELECDTRIC POTASSIUM LITHIUM NIOBATE CRYSTAL

用提拉法生长了完整透明的铁电铌酸钾锂晶体 .利用X 射线荧光光谱法测量分析了晶体的组成 .采用X 射线测量了晶体的结构 .用结构完整、组分均匀 ,尺寸为 6× 6× 7(a×b×c)mm3 的晶体样品 ,测量了晶体的拉曼光谱和红外折射光谱 .与其它钨青铜类晶体的晶格振动光谱进行比较 ,铌酸钾锂晶体中对称弯曲振动模式v5在拉曼光谱中分裂为 3个拉曼峰 ,反对称伸缩振动模式v3 和反对称弯曲振动模式v4在红外反射光谱中所对应的峰被加宽 ,v4被轻微分裂 .

Ferroelectric potassium lithium niobate crystals have been grown by using czochralski technique. The molecular formula of the crystal has been determined based on the Philips PW2400 X-ray fluorescent spectra. Homogeneous and crack free samples about 6 x 6 x 7 (a x b x c) were used to study the lattice vibration spectra using Raman and Infrared reflectivity spectroscopy. Compare with the lattice vibration spectra of other tungsten bronze ( TB) type crystals, the symmetric bend vibration mode nu(5) was split into three Raman lines, and the antisymmetric stretch vibration mode nu(3) and antisymmetric bend vibration mode nu(4) were all broadened greatly. This shows that Li ions in the C sites in the potassium lithium niobate crystal do influence on the Raman and inferred reflectivity spectra of [NbO6](7-) octahedron greatly.