立方相KTa_(0.67)Nb_(0.33)O_3晶体的系列相变研究

Study on Series of Phase Transitions in Cubic KTa_(0.67)Nb_(0.33)O_3 Crystal

采用拉曼散射技术研究了立方相KTa0.67Nb0.33O3晶体的系列相变,从声子角度分析了各相变特点。降温过程中立方-四方和四方-正交相变分别发生在-29℃和-95℃左右,正交-三方相变可能发生在-150℃左右。最后简单讨论了晶体的相变机制和居里点与晶体组分的关系,并比较分析了居里点的实验值与理论值的差异。

A series of phase transitions in cubic KTa0. 67Nb0. 33O3 crystal were researched by Raman scattering technique. Features on each phase transition were analyzed from the perspective of phonons.The cubic-tetragonal and tetragonal-orthorhombic phase transitions appear at about- 29 ℃ and- 95 ℃,respectively,and the orthorhombic-rhombohedral phase transition probably appears at about- 150 ℃ in cooling process. Finally,the phase transition mechanism and the relationship between curie temperature and crystal content were discussed,and the differences between experimental and theory Curie points were compared and analyzed.