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X-ray structural analysis of three dimensional quasicrystals

三维准晶的 X 射线结构分析

基本信息

批准号：
03452244
负责人：
NANAO Susumu
金额：
$ 4.22万
依托单位：
University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1991
资助国家：
日本
起止时间：
1991 至 1992
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-03452244/
关键词：
Quasicrystalline Alloy Three Dimensional Quasicrystal QCIC Model F-type Quasicrystal X-ray Diffraction X-ray Abnormal Scattering Atomic Cluster Environmental Structure 単結晶X線解析原子クラスタ-

项目摘要

Among the three dimensional quasicrystals, so called Mackay type and TC type quasicrystals are settling to the understanding of their atomic structures to be quasiperiodic arrangements of the atomic clusters with icosahedral symmetry, which are typically seen in QCIC (Quasiperiodic Configuration of Icosahedral Clusters) model proposed by the present group. The structures of so called F-type quasicrystals, which are recently discovered three dimensional quasicrystals, are still remained unknown.The objective of the present study is to analyze the atomic structures of the F-type quasicrystals in Al-Cu-Fe, Al-Cu-Ru and Al-Pd-Mn alloy systems in comparison with the structure of conventional Mackey type quasicrystals and to construct the structural models.The X-ray diffraction experiments were performed in Photon Factory of KEK. The diffraction profile was measured with powder samples. In the case of Al-Cu-Ru and Al-Pd-Mn systems, X-ray abnormal scattering was also measured at Ru edge and P … More d edge, respectively, in order to obtain the environmental structures around Ru and Pd atoms. Single crystals of the Al-Pd-Mn system were successfully grown by Bridgeman method and the diffraction was measured also for the single crystal.The X-ray diffraction profiles present the extra peaks with odd indices that come from the ordered structures in the quasicrystals. The total pair distribution functions and the environmental pair distribution functions were calculated from the profiles. The detailed analysis revealed that the F-type quasicrystals have very similar local structures to those in the conventional Mackay type quasicrystals, which indicates that the F-type quasicrystals are also consist of quasiperiodic configurations of icosahedral clusters.The models for F-type quasicrystals of Al-Cu-Ru and Al-Pd-Mn system were made, in which the two kinds of icosahedral clusters are arranged quasiperiodically and the clusters are distributed to the two kinds of quasilattice points according to the parity of the indices.The models reproduced well the diffraction profiles, pair distribution functions and the values of other parameters experimentally obtained, which indicates the framework of the models reflects the real structures of the F-type quasicrystals. Less

在三维准晶中，所谓的Mackay型和TC型准晶将其原子结构理解为具有二十面体对称性的原子团簇的准周期排列，这典型地出现在本课题组提出的QCIC（准周期二十面体团簇结构）模型中。 F型准晶是最近发现的三维准晶，其结构仍然未知。本研究的目的是分析Al-Cu-Fe、Al-Cu-Ru和Al-Pd-Mn合金体系中F型准晶的原子结构，并与常规Mackey型准晶的结构进行比较，并构建结构模型。 X射线衍射实验在KEK光子工厂进行。用粉末样品测量衍射曲线。对于Al-Cu-Ru和Al-Pd-Mn体系，还分别在Ru边缘和P… More d边缘测量了X射线异常散射，以获得Ru和Pd原子周围的环境结构。采用Bridgeman法成功生长了Al-Pd-Mn系单晶，并对单晶进行了衍射测量。X射线衍射谱显示出来自准晶有序结构的奇指数额外峰。根据剖面计算总对分布函数和环境对分布函数。详细分析表明F型准晶与常规Mackay型准晶具有非常相似的局部结构，这表明F型准晶也是由二十面体团簇的准周期构型组成。建立了Al-Cu-Ru和Al-Pd-Mn系F型准晶的模型，其中两种准晶二十面体团簇按准周期排列，并根据指数宇称分布到两种准晶格点上。模型很好地再现了实验获得的衍射谱、对分布函数和其他参数值，这表明模型的框架反映了F型准晶的真实结构。较少的