La_(1-x)Te_xMnO_3晶格结构的X射线粉末衍射分析  

XRD analysis on lattice structure of La_(1-x)Te_xMnO_3

作　　者：谈国太[1] 陈正豪[2] 

机构地区：[1]射线束技术与材料改性教育部重点实验室北京师范大学低能核物理所北京市辐射中心,北京100875 [2]北京凝聚态物理国家实验室中国科学院物理研究所,北京100080

出　　处：《物理学报》2007年第3期1702-1706,共5页Acta Physica Sinica

基　　金：国家重大基础研究项目基金(批准号:G1998061412);北京师范大学青年科学基金资助的课题.~~

摘　　要：通过X射线粉末衍射数据,用Rietveld精修方法分析了Te部分替换LaMnO3中La后,其晶格参数及其结构对称性所发生的变化.结果表明:Te掺杂LaMnO3系列样品具有R3C的晶格结构对称性,其MnO6八面体晶格还产生了伸张畸变,畸变程度随Te掺杂量的增加而增大.此外根据Mn—O—Mn键角、eg电子能带的带宽、A位离子平均半径及A位离子尺寸失配度等的变化特点,推测Te掺杂LaMnO3样品除居里温度等相变物理量将随x增加而非线性变化外,还可能产生自旋玻璃态、相分离等宏观现象.Based on X- ray powder diffraction data, the lattice structure and symmetry of La1-x Tex MnO3 （0.04 ≤ x ≤ 0.2） have been analyzed by Rietveld refining method, the results show that all samples structure have a rhombohedral symmetry with space group R 3^-C, and the lattice of MnO6 oetahedron has a stretching distortion due to the difference in cation size. Besides, the degree of structure distortion is closely related to Te content and can be depicted with the following three factors： the Mn--O--Mn bond angle θMn-O-Mn, the average A-site radius （ rA ） and the A-site size mismatch σ2 . According to the changing trend of these factors, several conjecture on physical properties are discussed, including the Curie temperature, spin-glass and phase separation etc.

关 键 词：庞磁电阻效应 La-Te-Mn-O X射线衍射 RIETVELD精修 

分 类 号：O482.3[理学—固体物理]