Structural studies of ceramic small crystals by synchrotron X-ray diffraction

本研究的目的是确定在各种环境条件下功能重要的晶体的准确和精确的结构，例如，各种温度、压力、磁场、静电场和湿度。使用单晶衍射技术的这种分析到目前为止一直受到消光效应的影响，消光效应通常会降低运动学理论所期望的入射强度。本研究从实用的观点出发，通过使用约10微米大小的小晶体和使用高通量的同步辐射源，似乎成功地解决了这个问题。测定了各种无机固溶体的非线性调制结构，研究了层状钙钛矿、LiCa_2Nb_3O_（10）、LiCa_2Ta_3O_（10）、RbCa_2Nb_3O_（10）、RbCa_2Ta_3O_（10）、NaCa_2Nb_3O_（10）、NaCa_2Ta_3O_（10）、HCa_2Nb_3O_（10）、HCa_2Ta_3O_（10）、SrMgF_4、BaMgF_4等的超结构。所有这些研究都是在光子工厂、高能物理实验室、日本和主要研究者的实验室进行的，使用的是最近为在环境条件下快速收集数据而开发的成像板三圆衍射仪。主要研究者现在牢记一个想法，即该项目已成功地由小组成员进行，其结果在很大程度上为涉及材料科学和晶体学的科学界做出了贡献。

The present study has been carried out with the objective to determine accurate and precise structures of functionally important crystals in various ambient circumstances, e.g., various temperatures, pressures, magnetic fields, electrostatic fields, and humidity. Such analyzes using the single crystal diffraction technique have so far been suffered from the extinction effect which often reduces the incident intensity expected from the kinematical theory. The present study seems to have succeeded in eliminating the problem from practical point of view, by the use of small crystal of about 10 micrometer in size and by the use of the synchrotron source with high flux. The results obtained are determination of incommensurately modulated structures in various inorganic solid solution, investigation of the superstructures of layered perovskites, LiCa2Nb3O10, LiCa2Ta3O10, RbCa2Nb3O10, RbCa2Ta3O10, NaCa2Nb3O10, NaCa2Ta3O10, HCa2Nb3O10, HCa2Ta3O10, SrMgF4, BaMgF4 and so forth. All these studies were done at the Photon Factory, High-Energy Physics Laboratory, Japan, and at the principal investigator's laboratory using the imaging-plate three-circle diffractometer which has been recently developed for the rapid data collection at ambient conditions. The principal investigator now bears in mind a thought that this project has successfully conducted by the group members and the results have contributed to the scientific communities involved in the materials science and crystallography to a great extent.