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从声子-电磁激元频率色散关系的普遍公式出发,推导出了单轴晶体的Merten方程和电磁激元的频率色散关系。测量了BaTiO_3和Ce:BaTiO_3晶体的简正模和斜声子的喇曼散射谱,并根据Merten方程,拟合出了斜声子的方向色散曲线;记录了A_1类电磁激元在不同波矢值下的喇曼谱,观察到其频率色散现象.根据以上结果,对A_1(TO)模喇曼谱中两个宽的非对称峰的归属和BaTiO_3晶体的结构相变机制进行了讨论;计算出了这两种晶体的受夹介电常数;分析了掺Ce对BaTiO_3晶体结构的影响。
Based on the universal formula of frequency dispersion of phonon-electromagnet, the relationship between the Merten equation of uniaxial crystal and the frequency dispersion of electromagnetic exciton is deduced. The Raman scattering spectra of normal mode and oblique phonons of BaTiO_3 and Ce: BaTiO_3 crystals were measured. According to the Merten equation, the directional dispersion curves of the phonons were fitted. The A_1-type electromagnetic excitations were recorded at different wave-vector values And the frequency dispersion phenomenon was observed.According to the above results, the attribution of two broad asymmetric peaks in A_1 (TO) Raman spectra and the structural phase transition mechanism of BaTiO_3 crystal were discussed. The dielectric constants of these two kinds of crystals were investigated. The influence of Ce on the crystal structure of BaTiO_3 was analyzed.