La0.55Ca0.45MnO3的电子密度分布变温X射线衍射测量

运用X射线衍射(XRD)分析技术,对钙钛矿型La_0.55Ca_0.45MnO₃化合物的空间结构进行了变温测量,用Rietveld方法对XRD实验数据进行了精修拟合.随着温度的降低,实验上观测到衍射峰的劈裂,暗示该化合物内部晶体结构发生了相变.磁化曲线测量表明,对应晶体结构相变的温度,化合物的磁性也发生由铁磁性向反铁磁性的转变.运用Rietica软件对化合物的XRD数据进行了处理,得到了La_0.55Ca_{0.45<关键词：锰氧化物相变电子密度分布磁结构}

Electronic density distribution of La0.55 Ca0.45 MnO3 revealed by temperature-dependent X-ray diffraction

The temperature-dependent spatial structure of perovskite oxide La_0.55Ca_0.45MnO₃ has been checked by X-ray diffraction (XRD) and Rietveld method was employed to refine the XRD data. It was found that with the decrease of temperature, almost all of the diffraction peaks were split; each peak was divided from single peak at high temperature into two peaks at low temperature, indicating the appearance of a crystalline structural phase transition. Corresponding to the structural phase transition, magnetization measurements also revealed a magnetic transition from ferromagnetism to antiferromagnetism. With the Rietica analysis of the XRD data of the compound, plots of the electronic density distribution of La_0.55Ca_0.45MnO₃ were made. Sharp difference in the distributions above and below the transition temperature was clearly shown. Taking the magnetism of the compound into consideration, the structural phase transition was analyzed and the sharp difference of the electronic density distribution was qualitatively explained.