BiFeO_3高压拉曼光谱研究  

High Pressure Raman Investigation of BiFeO_3

作　　者：韩茜 吴也 黄海军[1] HAN Xi;WU Ye;HUANG Haijun(School of Sciences,Wuhan University of Technology,Wuhan 430070,China)

机构地区：[1]武汉理工大学理学院,湖北武汉430070

出　　处：《高压物理学报》2018年第5期40-44,共5页Chinese Journal of High Pressure Physics

基　　金：973项目(2014CB845904);国家自然科学基金(41322028);中央高校基本科研业务费专项资金资助项目(2015Ⅲ035;2014Ⅶ006)

摘　　要：BiFeO_3是少数在室温下同时具有铁电有序和铁磁有序的多铁材料之一。BiFeO_3在室温下呈扭曲的三方钙钛矿结构,满足R3c空间群。通过六面顶大压机在高温高压下合成纯的BiFeO_3粉晶,并结合高压拉曼光谱测试技术,得到了0~44GPa压强下BiFeO_3的拉曼光谱。结果表明:随着压强的增加,低波数的拉曼峰逐渐向高波数迁移并展宽,位于145、177和231cm-1的拉曼峰强度逐渐减弱。第一次相变发生在5GPa左右,位于145cm-1左右的拉曼峰消失,与此同时在217cm-1左右出现新的拉曼峰。当压强增加到11GPa时,明显观察到位于340cm-1左右的拉曼峰出现,而低波数(<200cm-1)的拉曼峰则全部消失,标志BiFeO_3发生第二次相变,转为正交晶系的Pnma结构。压强增加到38GPa时,BiFeO_3发生第三次相变,位于340cm-1左右的拉曼峰消失,谱线上不存在明显的拉曼峰,BiFeO_3可能由正交晶系的Pnma结构转变为Pnmm结构或高对称的立方晶系结构。BiFeO 3 is one of the most promising multiferroics that exhibits both magnetic and ferroelectric properties above room temperature.The room-temperature structure of BiFeO 3 is a highly rhombohedrally distorted perovskite with space group R3c.In this study,we prepared BiFeO 3 powder under high temperature and high pressure using muti-anvils,and investigated the phase transition of BiFeO 3 in the 0-44 GPa range combinng with Raman spectrum.Upon compression,the low-frequency Raman modes of BiFeO 3 shift to higher angles and become broadening,and the vibrational modes at 145,177 and 231 cm-1 begin to decrease.The first phase transition takes place at the pressure of about 5 GPa,shown by the disappearance of the mode at 145 cm-1 and the emergence of the mode at 217 cm-1.The second phase transition is indicated by the emergence of the mode at 340 cm-1 and the disappearance of the mode below 200 cm-1 at 11 GPa.After this phase transition,the structure of BiFeO 3 transfers to orthorhombic phase Pnma.The third phase transition takes place at the pressure of 38 GPa,all the Raman modes including the mode at 340 cm-1 disappear,and the structure of BiFeO 3 may transferr to cubic or higher symmetry orthorhombic crystals.

关 键 词：BIFEO3 高压 拉曼光谱 相变 

分 类 号：O521.23[理学—高压高温物理]