A位有序钙钛矿结构RBaMn2O6材料磁-电耦合效应研究

项目名称： A位有序钙钛矿结构RBaMn2O6材料磁-电耦合效应研究

项目编号： No.50872148

项目类型： 面上项目

立项/批准年度： 2009

项目学科： 化学工业

项目作者： 李静波

作者单位： 中国科学院物理研究所

项目金额： 37万元

中文摘要： 课题开展了A 位有序钙钛矿锰氧化物YBaMn2O6（La替代Y、Sr替代Ba）相关体系、Bi1-xCaxMnO3和Bi1-xSrxMnO3 (x=0.3-0.7)体系、BixGd1-xFeO3 (x=0-0.5)和Bi4Bin-3Ti3Fen-3O3n+3 (n = 3-9)体系的研究工作。制备了系列化合物样品；开展了磁、电、热和磁-电耦合效应的观测；利用高分辨和变温XRD，开展Rietveld结构精修、电子密度分布最大熵分析和键价分析，结合物理性能，研究结构-性能关系，解释物理机制。实验证明YBaMn2O6及相关化合物低温存在类自旋玻璃行为。掺入La，(Yx,La1-x)BaMn2O6由室温反铁磁向铁磁转变，x=0.5处为结构和磁转变相界。10 at% Sr替代量导致Y(Bax,Sr1-x)Mn2O6由P2向P1转变。初步完善了电子密度分布最大熵分析方法。构建了BixGd1-xFeO3物理性能和结构相图，在该体系中观察到了正、负磁-介电效应，根据结构分析阐明了磁-电效应机制。项目的研究对多铁性材料探索和晶格-自旋交互作用等科学问题具有重要的学术意义。

中文关键词： 多铁性材料；A 位有序钙钛矿锰氧化物；X 射线衍射结构分析；晶体结构；磁性

英文摘要： A-site ordered perovskites of YBaMn2O6, (Yx,La1-x)BaMn2O6 and Y(Bax,Sr1-x)Mn2O6, Bi-doping perovskite manganites of Bi1-xCaxMnO3 and Bi1-xSrxMnO3, and BiFeO3-related compounds of BixGd1-xFeO3 and Bi4Bin-3Ti3Fen-3O3n+3 (n = 3-9) were synthesized. The magnetism, resistivity, ferroelectricity, dielectric response, thermal effect and magnetodielectric properties were investigated. The crystal structures of the oxides were investigated by high resolution temperature-dependent XRD, NPD and TEM. Based on detailed structure analyses (including reconstruction of electron density), the structure-property relationships and the mechanism of physical properties were discussed. In YBaMn2O6 and related compounds a low-temperature spin-glass-like transition was verified. At x=0.5, (Yx,La1-x)BaMn2O6 compounds undergo a P2-P4/mmm structural transformation and a antiferromagnatism-ferromagnetism transition at room temperature. 10 at% Sr substituting for Ba leads to a P2 to P1 transformation in Y(Bax,Sr1-x)Mn2O6. MEM electron density distribution method was improved for further detailed electron orbital analysis. A physical property phase diagram of the BixGd1-xFeO3 system was constructed. Based on the structural analysis, the magnetoelectric effect observed in BixGd1-xFeO3 compounds was reasonably interpreted. The achievement resulting from the project is of significance for the exploration of multiferroic materials as well as for understanding the lattice-spin interaction in strongly correlated electron systems.

英文关键词： multiferroite; A-site ordered perovskite manganites; X-ray diffraction analysis; crystal structure; magnetism