A位无序掺杂锰氧化物La2/3-xYxCa1/3-ySryMnO3的微结构和居里温度研究

采用固相反应法制备了A位无序掺杂锰氧化物La2/3-xYxCa1/3-ySryMnO3系列样品;利用Rigaku Dmax-rB 12 kW转靶X-ray衍射仪和振动样品磁强计Lakeshore7300对样品进行表征,并通过Rietveld方法对X-ray衍射谱进行结构精修。讨论了A位掺杂无序度σ2对样品的相、微结构（Mn—O键长、Mn—O—Mn键角等参数）和居里温度的影响。结果表明：随着掺杂浓度x和无序度σ2的增加,样品仍然保持单相性较好的钙钛矿正交结构,晶格常数a,b,c和晶胞体积V没有发生大的变化;Mn—O—Mn键角增加和Mn O键长减小;样品的居里温度下降,但x=0.20时,La2/3-xYxCa1/3-ySryMnO3居里点反而拉伸增大。

Study on Microstructure and Curie Temperature of A- sites Size-Disorder La2/3 -x Yx Ca1/3-y Sry MnO3 Compounds

A series of manganese oxides La2/3-xYxCa1/3-ySryMnO3 were prepared by solid phase reaction method;the structure and phase of samples were carried out by X-ray diffraction instrument with Rigaku Dmax-rB 12 kW and the dependence of magnetization（M） on temperature（T） was measured by VSM Lakeshore7300.The lattice parameters and Mn—O—Mn band angle were obtained from refinement results calculated by Rietveld method.The results show that the lattice constants of the series of samples change scarcely and perovskite orthorhombic structure with single phase is kept as the doped concentration（x） and doped disorder degree（σ2） increase,but Curie temperature（Tc） decreases.When x=0.20,Curie temperature of the sample La2/3-xYxCa1/3-ySryMnO3 increases reversely.