The Phason Observation in Al-Pd-Mn Icosahedral Quasicrystals using with the temperature dependence of the lattice constants

本研究的主要目的是研究Al-Pd-Mn二十面体相的准晶相稳定性。已有报道，A1PdMn与其他二十面体相不仅是f型二十面体相，还可以是f2型和f2m型二十面体相。散射强度的实验结果如下：1) Al-Pd-Mu的横向扩散呈椭圆形，Al-Cu-Fe的横向扩散呈不对称的菱形。2) Al-Pd-Mu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) Al-Cu-Fe的散射强度与300k以下温度的关系不大。5)散射强度与q量级的n次方成正比，n的取值范围在-2 ~ -3.5之间，与方向和反射有关。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地解释为黄散射的每一张图，它似乎由所有三个分量的总和组成。作为实验和计算的对比，我们可以想到以下几点。Al-Pd-Mu和Al-Cu-Fe的主要缺陷可以是由原子和/或原子团簇交换产生的交换型缺陷。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。Al-Cu-Fe相缺陷的类型与交换型缺陷相似，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。主要的缺陷是交换型缺陷，这是由原子和/或原子簇的交换产生的。由于这类缺陷，原子和原子团簇的浓度与理想结构相比没有变化。随机相位子显然属于这一类。结果表明，在Al-Cu-Fe相中存在额外类型的缺陷。“不对称”和n次幂依赖不能用黄散射的弹性近似来解释。少

The main aim of this research is to study the quasicrysta phase stability of Al-Pd-Mn icosahedral phase. It have already been reported that an A1PdMn and the other icosahedral phases is not only an F-type icosahedral phase, but can be F2-type and F2M-type icosahedral phases. The experimental results of the diffuse scattering intensity are as follows.1) The diffuse distribution of Al-Pd-Mu is elliptic spread toward the transverse direction, but that of Al-Cu-Fe is asymmetrical rhombic shape. 2) The diffuse scattering intensity distribution of Al-Pd-Mu 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 not just 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.5) The diffuse intensity is pro … More portional to the nth power of the magnitude of q. The values of n range between -2 and -3.5 and depend on the direction and reflection.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 components.As the comparison between experimental and calculation, we can think followings. The major defects in Al-Pd-Mu and Al-Cu-Fe can be exchange-type defects 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 a defect in the Al-Cu-Fe phase 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.The major defects are exchange-type defects which are created by interchange of atoms and/or atomic clusters. And 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 results indicate presence of additional type of defect in the Al-Cu-Fe phase. The "asymmetrical" and the nth power dependence cannot be explained with the elastic approximation of Huang scattering. Less