A polarized micro-Raman study of a 0.65PbMg_(1/3)Nb_(2/3)O_3-0.35PbTiO_3 single crystal  

作　　者：Zhang Li-Yan Zhu Ke Liu Yu-Long 张丽艳;朱恪;刘玉龙(Institute of Physics,Chinese Academy of Sciences,Beijing 100190,China)

机构地区：[1]Institute of Physics,Chinese Academy of Sciences,Beijing 100190,China

出　　处：《Chinese Physics B》2012年第1期482-487,共6页中国物理B（英文版）

基　　金：Project supported by the National Natural Science Foundation of China(Grant Nos.10674171 and 10874236)

摘　　要：Polarized micro-Raman spectra of a 0.65PbMgl/3Nb2/303 0.35PbTiO3 （0.65PMN-0.35PT） single crystal poled in the [001] direction are obtained in a wide frequency range （50 2000 cm^-1） at different temperatures. The best fit to the Raman spectrum at 77 K is achieved using 17 Lorenzians to convolute into it, and this is proved to be a reasonable fit. According to the group theory and selection rules of overtone and combinational modes, apart from the seven Raman modes that are from first-order Raman scattering, the remaining ones are attributed to being from second-order Raman scattering. A comparison between the experimental results and theoretical predictions shows that they are in satisfactory agreement with each other. Our results indicate that at 77 K the sample belongs to the rhombohedral symmetry with the C^53v（R3m） space group （Z = 1）. In our study, on heating, the 0.65PMN 0.35PT single crystal undergoes a rhombohedral → tetragonal → cubic phase transition sequence. The two phase transitions occur at 340 and 440 K, which correspond to the disappearance of the soft mode near 106 cm-1 recorded in VV polarization and the vanishing of the band around 780 cm^-1 in VH polarization, respectively.Polarized micro-Raman spectra of a 0.65PbMgl/3Nb2/303 0.35PbTiO3 （0.65PMN-0.35PT） single crystal poled in the [001] direction are obtained in a wide frequency range （50 2000 cm^-1） at different temperatures. The best fit to the Raman spectrum at 77 K is achieved using 17 Lorenzians to convolute into it, and this is proved to be a reasonable fit. According to the group theory and selection rules of overtone and combinational modes, apart from the seven Raman modes that are from first-order Raman scattering, the remaining ones are attributed to being from second-order Raman scattering. A comparison between the experimental results and theoretical predictions shows that they are in satisfactory agreement with each other. Our results indicate that at 77 K the sample belongs to the rhombohedral symmetry with the C^53v（R3m） space group （Z = 1）. In our study, on heating, the 0.65PMN 0.35PT single crystal undergoes a rhombohedral → tetragonal → cubic phase transition sequence. The two phase transitions occur at 340 and 440 K, which correspond to the disappearance of the soft mode near 106 cm-1 recorded in VV polarization and the vanishing of the band around 780 cm^-1 in VH polarization, respectively.

关 键 词：0.65PMN-0.35PT  polarized micro-Raman second-order Raman scattering  phase tran-sition 

分 类 号：O482.3[理学—固体物理]