新型多晶材料结构与磁结构的中子衍射研究

项目名称： 新型多晶材料结构与磁结构的中子衍射研究

项目编号： No.11275012

项目类型： 面上项目

立项/批准年度： 2013

项目学科： 数理科学和化学

项目作者： 林建华

作者单位： 北京大学

项目金额： 100万元

中文摘要： X-射线和中子衍射是结构研究中最基本的两种方法，将二者结合起来用于凝聚态物质的探索，近年来取得了多项令人瞩目的进展。本项目将从新材料的合成出发，在X-射线衍射等方法确定晶体结构模型的基础上，进一步收集中子衍射数据，利用Rietveld精修确定所有元素的准确位置和占有率；根据磁性质随温度的变化情况，确定中子衍射的温度范围，观察磁有序而导致的新的衍射峰和原有衍射峰强度的变化情况，开展磁有序结构的研究；综合分析晶体结构和磁结构数据与材料的物理化学性质特别是磁性变化特点，理解结构与性能之间的关系。通过本项目的研究，将建立粉末X射线与中子衍射确定新型固体材料结构的解析方案，了解磁结构排布的微观机制，探讨结构与功能关系，为新型功能材料的设计合成提供指导。

中文关键词： X射线衍射；中子衍射；Rietveld 方法；晶体结构；磁结构

英文摘要： X-ray and neutron diffractions are two essential probes for the structure study. Their combined application in condensed-matter research has led to outstanding worldwide breakthroughs in recent years. This research program takes advantage of, on the neutron side, the keen sensitivity to light elements and the high contrast in resolving different elements. On the chemistry side, from the preparation of novel crystalline compounds, we determine their initial structural model by X-ray, electron-microscopy, and other characterization, and then perform the neutron powder diffraction, to get the accurate atomic coordinates and site occupancy of all the elements by Rietveld refinement, thus achieving a full crystallographic structure. According to the magnetic properties such the magnetic susceptibility data of the compounds, temperature-variable neutron diffraction experiments are taken for the further invetigations of magnetic structures. Magnetic ordering will manifest itself with new magnetic reflections and/or superimposed intensity at the nuclear Bragg peaks. The information regarding the crystal and magnetic structures will be correlated with the data of the chemical and magnetic behavior of the samples, which will shed light into understanding the relationship between the crystal/magnetic structures and the ch

英文关键词： X-ray diffraction；neutron diffraction；Rietveld method；crystal structure；magnetic structure