Dislocations in quasicrystals

准晶体中的位错

基本信息

批准号：
11650674
负责人：
EDAGAWA Keiichi
金额：
$ 2.62万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2001
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-11650674/
关键词：
quasicrystal dislocation mechanical property plasticily phason icosahedra phase decagonal phase

项目摘要

In quasicrystals, we can define a dislocation whose Burgers vector is a lattice translational vector of a 4D or higher dimensional lattice. Such a dislocation is a novel type of structural defect inherent to quasicrystal in the sense that it is accompanied not only by a conventional strain but also by a strain named phason strain which is caused by a lattice distortion in a complementary space orthogonal to real space. We performed the following researches for the purpose of clarifying the properties of such a dislocation. First, we perfomed plastic deformation experiments for icosahedra (i-) Al-Pd-Mn and decagonal (d-) Al-Ni-Co. For both samples, work softening, which is generally seen for quasicrystals, was observed. As a result of thermal activation analysis, we analyzed the data at various temperatures systematically on the assumption of temperature-dependent dragging stress for a dislocation. Second, we investigated structure and properties of phasons, which play an important role in the dynamical property of the dislocation in quasicrystals. Here, i) we observed the structure of a phason defect by STM, ii) we measured specific heat at high temperatures to investigate thermally equilibinium phasons and iii) we observed the phasons in motion at high temperatures by in-situ high-temperature HRTEM. In i), we observed a frozen-in phason defect in d-Al-Ni-Co by STM. In ii), we measured specific heat (Cp) of i-Al-Pd-Mn and d-Al-Cu-Co by DSC. we observed an upward deviation of Cp from the Dulong-Petit value of 3k/atom (k : Boltzman's constant) and it reached 5k at about 800℃. This can be interpreted as a thermal excitation of phasons. We calculated the entropy change from the increment of Cp and compared it with the result of the computer simulations previously done. In iii), we observed directly phasons in motion by HRTEM for the first time.

在准晶体中，我们可以定义一个脱位，其汉堡矢量是4D或更高尺寸晶格的晶格翻译向量。这种错位是一种新型的类型的类晶体固有的结构缺陷，在某种意义上，它不仅是通过常规菌株来实现的，而且是由名为相菌株的菌株来完成的，该菌株是由互补空间中的晶格失真引起的，互补空间正交到真实空间。我们进行了以下研究，目的是阐明这种错位的特性。首先，我们针对Icosahedra（I-）Al-PD-MN和decagonal（d-）al-Ni-CO的塑性变形实验。对于这两个样品，都观察到通常可以看出准晶体的工作软化。由于热激活分析，我们系统地在各种温度下分析了数据依赖温度依赖性拖动应力的数据。其次，我们研究了拟南芥的结构和特性，这些结构和特性在准晶体中位错的动态特性中起重要作用。在这里，i）我们观察到了STM的相缺陷的结构，ii）我们在高温下测量了比热等效相位的特定热量，iii）我们观察到通过原位高温HRTEM在高温下运动的相位。在i）中，我们通过STM观察到D-Al-Ni-CO中的冷冻相缺陷。在II）中，我们通过DSC测量了I-AL-PD-MN和D-AL-CO-CO的比热（CP）。我们观察到CP从3K/ATOM的Dulong-Petit值（K：Boltzman的常数）的向上偏差，并且在约800℃时达到5K。这可以解释为相的热兴奋。我们从CP的增加中计算了熵变化，并将其与先前完成的计算机模拟结果进行了比较。在iii）中，我们首次通过HRTEM直接观察到了运动。