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

本研究的主要目的是研究Cu-Ga-Zn-Mg二十面体准晶相的稳定性。已有报道CuGaZnMg为p型二十面体相。但是其他的二十面体相是f型二十面体。我们编制了二十面体对称晶体的黄散射程序。二十面体相的实验结果如下：1)在Cu-Ga-Zn-Mg二十面体相中，UPS观察到费米表面周围的赝隙，而在Ga-Zn近似中没有观察到赝隙。2)间隙深度为0.6 ev，宽度为0.2eV。x光片的研究非常困难。其中一个原因似乎是多重散射效应不容忽视。黄光散射强度的计算结果在二十面体相如下：1)沿2重轴方向反射周围黄漫反射沿横向呈椭圆形扩散。2)黄漫反射分布，沿5重轴和3重轴沿反射面周围的黄漫反射分布，在横向上不呈椭圆形扩散，呈复杂形状。3) Al-Pd-Mn的扩散散射强度沿纵向分布是对称的，Al-Cu-Fe的扩散散射强度沿纵向分布是不对称的。原因，在这种情况下被称为“不对称”，是菱形的中心不仅在衍射点上，而且位于稍微内侧。3)散射强度轮廓的形状取决于强度。4)在300K以下，Al-Cu-Fe的散射强度与温度的关系不大。因此，认为漫射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/或缺陷外，准晶体中还自然包含一种称为（冷冻）“相子”的缺陷。实验结果似乎表明弹性近似的极限为黄散射。漫射散射强度的轮廓线不能单独解释为黄散射的每一张图，它似乎由所有三个漫射散射分量的总和组成。作为实验和计算的对比，我们可以想到以下几点。Al-Pd-Mn和Al-Cu-Fe中的主要缺陷可以是交换型缺陷，这是由原子和/或原子团簇的交换产生的。然而，由于这种类型的缺陷，原子和原子团簇的浓度与理想结构没有变化。随机相位子显然属于这一类。缺陷的类型与交换型相似，但伴随着原子和原子团簇浓度与理想状态的偏差。由于“不对称”不能用黄散射的近似来解释，它可能是由尺寸效应引起的。少

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