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The Determination the Phason in Cu-Ga-Zn Icosahedral Quasicrystal Phase using with the Huang Diffuse Scattering method

黄漫散射法测定Cu-Ga-Zn二十面体准晶相中的相子

基本信息

批准号：
15540306
负责人：
MORI Masahiro
金额：
$ 2.3万
依托单位：
NAGOYA UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2003
资助国家：
日本
起止时间：
2003 至 2004
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-15540306/
关键词：
Quasicrystal Icosahedral phason x-ray diffraction electron diffraction diffuse scattering Zn X線回析電子線回析

项目摘要

The main aim of this research is to study the quasicrystal phase stability of Cu-Ga-Zn-Mg icosahedral phase. It have already been reported that a CuGaZnMg is an P-type icosahedral phase. But the other icosahedral phases are F-type icosahedral. We have made the program of the Huang scattering for icosaheral symmetry crystal. The experimental results o are in the icosahedral phases as follows.1)The pseudo-gap around the Fermi surface in the Cu-Ga-Zn-Mg icosahedral phase is observed by the UPS study and that in the Ga-Zn approximant is not observed. 2)The depth and width of the gap is 0.6 and 0.2eV, respectively. 3)It is very difficult for the x-ray study to be done. It seems that one of the reason is multi scattering effect is not ignored.The calculated results of the Huang scattering intensity are in the icosahedral phases as follows.1)The Huang diffuse distribution around the reflection along the 2-fold axis is elliptic spread toward the transverse direction. 2)The Huang diffuse distri … More bution around the reflection along the 5-fold and 3-fold axis is not elliptic spread toward the transverse direction and like the complex shape. 3)The diffuse scattering intensity distribution of Al-Pd-Mn is symmetrical along the longitudinal direction, but that of Al-Cu-Fe is asymmetric. The reason, called "asymmetrical" in this case, is that the center of the rhombus is notjust on the diffraction point, but is located on the slightly inside. 3)The shape of diffuse intensity contour depends on the intensity. 4)The intensity of the diffuse scattering in Al-Cu-Fe depends little on the temperature below 300K.Therefore, it is thought that the diffuse scattering is mainly produced by the defects. In the defects, a defect, called a (frozen) "phason" proper to a quasicrystal, is naturally included besides an impurity and/or defect included in a "usual" crystal. The experimental result seems to show the limit of elastic approximation as Huang scattering. The contour of the diffuse scattering intensity cannot individually be explained as every map of Huang scattering, and seems to consist of the sum of all three diffuse scattering components.As the comparison between experimental and calculation, we can think followings. The major defects in Al-Pd-Mn and Al-Cu-Fe can be exchange-type, which are created by interchange of atoms and/or atomic clusters. However, the concentration of atoms and atomic clusters is unchanged from the ideal structure by this type of defect. Random phason is clearly classified into this type. The type of the defect is similar to the exchange-type but is accompanied by deviation of concentration of atoms and atomic clusters from the ideal state. As the "asymmetrical" cannot be explained with the approximation of Huang scattering, it is probably caused by a size effect. Less

本研究的主要目的是研究铜-镓-锌-镁二十面体相的准晶相稳定性。已有报道称CuGaZnMg为P型二十面体相。而其他二十面体相为F型二十面体。编制了二十面体对称晶体的黄光散射程序。实验结果如下：1)UPS研究发现，在铜-镓-锌-镁二十面体相中存在费米面附近的假间隙，而在近二十面体相中未观察到假间隙。2)能隙的深度和宽度分别为0.6 eV和0.2 eV。3)X射线研究难度大。其中一个原因似乎是多次散射效应没有被忽略。黄光强的计算结果是在二十面体位相中。1)黄光散射分布沿2重轴方向的反射是椭圆形的。2)黄漫散地…更多的反射沿5重和3重轴线的方向不是椭圆形，而是向横向扩散，形状复杂。3)Al-Pd-Mn的扩散散射强度沿纵向呈对称分布，而Al-Cu-Fe的扩散散射强度沿纵向分布不对称。其原因，在这种情况下称为“不对称”，是因为菱形的中心不仅在衍射点上，而且位于略微内侧。3)漫反射强度轮廓的形状取决于强度。4)Al-Cu-Fe的扩散散射强度与300K以下的温度关系不大，因此认为扩散散射主要是由缺陷引起的。在缺陷中，除了“通常”晶体中包含的杂质和/或缺陷之外，自然还包括准晶特有的(冻结的)“相子”缺陷。实验结果似乎表明弹性近似为黄散射的极限。漫散射强度的等高线不能单独解释为黄光散射图的每一幅，而是由三个漫散射分量的总和组成。Al-Pd-Mn和Al-Cu-Fe中的主要缺陷可能是通过原子和/或原子团簇的互换而产生的交换型缺陷。然而，由于这类缺陷，原子和原子团簇的浓度与理想结构保持不变。随机相干子被明确地归类为这种类型。缺陷的类型类似于交换型，但伴随着原子和原子团簇的浓度偏离理想态。由于这种“不对称性”不能用黄光散射的近似来解释，它很可能是由尺寸效应引起的。较少