STM and STS studies of atomic structure and electronic states in quasicrystals

准晶体中原子结构和电子态的 STM 和 STS 研究

基本信息

批准号：
14550649
负责人：
EDAGAWA Keiichi
金额：
$ 2.56万
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：
2002
资助国家：
日本
起止时间：
2002 至 2003
项目状态：
已结题

项目摘要

For the purpose of investigating atomic structure and electronic states In quasicrystals, we performed the following experiments. For a single-grained decagonal quasicrystal in the AL-Ni-Co system grown by Czochralski method, STM observations and tunneling spectroscopy were done. By STM the followings were observed: i)high perfection in the quasiperiodicity in the atomic arrangement, ii)10_5screw relation between the two kinds of quasiperiodic layers, iii)various periodicities in the atomic arrangement along the tenfold direction by surface reconstruction and iv) very low density of pason defects. In particular, the result iv) presents the first example of STM observation of any phason defect. By tunneling spectroscopy we found several peaks corresponding to surface states. In relation to the result iv), we investigated the phason relaxation process in quasicrystal by high-temperature in-situ HRTEM. The sample we used was an Al-Cu-Co decagonal quasicrystal. First, we introduced a uniform phason strai by 820℃ annealing. Then, we raised the temperature to 850℃ and observed the phason relaxation process. It was found that the phason relaxation proceeds with the shift of the boundary between the region with the uniform phason strain and the phason-free region. In this process the phason displacement in the region with the uniform phason strain remains unchanged and the tiling always continues coherently across the boundary.

为了研究准碘的原子结构和电子状态，我们进行了以下实验。对于通过Czochralski方法生长的Al-Ni-CO系统中的单个粒度甲状管静态，进行了STM观测和隧道光谱。通过STM观察到以下内容：i）原子布置中的准碘的高度完美，ii）两种类型的准二层层之间的10_5screw关系，iii）iii）各种周期性的各种周期性，沿原子布置沿着tenfold方向沿着表面重建方向和IV的高密度沿ten倍的方向进行了非常低的密度。特别是，结果iv）提出了对任何相缺陷观察的第一个例子。通过隧道光谱法，我们发现了与表面状态相对应的几个峰。关于结果iv），我们通过高温度的原位HRTEM研究了准晶体中的相松弛过程。我们使用的样品是al-cu-co decagonal准晶体。首先，我们在820℃退火时引入了统一的strai。然后，我们将温度升高到850℃，并观察到相弛豫过程。发现相位弛豫是随着均匀相应变和无相区域之间边界的变化而进行的。在此过程中，具有均匀相应变的区域中的相位位移保持不变，并且瓷砖始终在整个边界上保持一致。