Study of Electronic Structures near Lattice Defects in Metals by the Measuretment of Electron Momentum Distributions

通过测量电子动量分布研究金属晶格缺陷附近的电子结构

• 批准号: 61460197
• 负责人: TANIGAWA Shoichiro
• 金额: $ 4.22万
• 依托单位: University of Tsukuba
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for General Scientific Research (B)
• 财政年份: 1986
• 资助国家: 日本
• 起止时间: 1986 至 1987
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-61460197/
• 关键词: Positron Annihilation; Two-dimensional Angular Correlation of Annihilation Radiations(2D-ACAR); electron momentum distribution; lattice defects; electronic structure of lattice defects; fermi surface; 原子励起子

As compared with colour centers in ionic crystals and vacancy-oxygen complex in silicon crystals, the electronic structure of lattice defects in metals is not yet clear enough. However, recent developments in the measurement of two-dimensional angular correlation of annihilation radiations have allowed us to start precise and realistic investigations of electron momentum distributions and electron wavefunctions near lattice defects in metals and alloys. The purpose of the present project is to understand the electronic structure of lattice defects both in reciprocal space and in real space, by means of the two dimensional angular correlation machine and by their expansion. Results are summarized as follows;(1) The expansion of two-dimnsional angular correlation machin: we were successful in expanding the 128 detector system to the 256 detector systemby the use of specially designed electronic circuit. We raised the counting rate about four times.(2) The measurement of electron momentum … More distribution near thermal equilibrium defects in pure aluminum and aluminum based dilute alloys: We found that the Doppler broadening of annihilation radiations shows an abnormal narrowing near melting point in dilute alloys. This effect could not be observed by the measurement of positron lifetimes. In the 2D-ACAR experiment, the derived autocorrelation function is explained by the presence of vacancies in intermediate temperature range, but that near melting point corresponds to the presence of positroniums. From this fact, we proposed a nex positron trapping model.(3) The determination of Femi surface in oxide high temperature superconductors: In order to search the effect of oxygen deficiency, we did 2D-ACAR experiment. We cound not find any effect. From this fact, in turn, we can determine the Fermi surface. It was perfectly two-dimensional and one electron pillar and two kinds of hole pillars were found. (4) The direct observation of atomic excitons in lead based dilute alloys, and, (5) The measurement of electron momentum distribution around vacancies in electron irradiated nickel and the effect of hydrogens on it were performed. Less

与离子晶体中的色心和硅晶体中的空位-氧复合体相比，金属中晶格缺陷的电子结构还不够清楚。然而，最近在测量湮灭辐射的二维角关联方面的进展使我们能够开始精确和现实地研究金属和合金中晶格缺陷附近的电子动量分布和电子波函数。本项目的目的是通过二维角相关机及其展开来理解晶格缺陷在倒易空间和实空间中的电子结构。结果总结如下：(1)二维角相关机的扩展：利用专门设计的电路，成功地将128个探测器系统扩展为256个探测器系统。我们将计数率提高了四倍左右。(2)电子动量…测量在纯铝和铝基稀合金的热平衡缺陷附近有更多的分布：我们发现在稀合金中，湮没辐射的多普勒展宽在熔点附近出现反常的收窄。这种效应不能通过正电子寿命的测量来观察到。在2D-ACAR实验中，导出的自相关函数是由中温区空位的存在解释的，但在熔点附近的自相关函数对应于正电子的存在。氧化物高温超导体中FeMI表面的测定：为了探索氧缺乏的影响，我们进行了2D-ACAR实验。我们找不到任何效果。根据这一事实，反过来，我们可以确定费米面。它完全是二维的，并且发现了一个电子柱和两种空穴柱。(4)直接观测铅基稀薄合金中的原子激子；(5)测量电子辐照镍中空位周围的电子动量分布及氢对其的影响。较少

项目成果

谷川庄一郎: 日本金属学会会報.

Shoichiro Tanikawa：日本金属研究所通报。

S. Tanigawa: Maruzen. Positron Annihilation Technique in Oyo-Butsuri Handbook,

S. 谷川：丸善。

I. Kanazawa: J. Phys. Chem. of Solids. 48. 701-705 (1987)

I.金泽：J.Phys。

谷川庄一郎 他: "応用物理学ハンドブック(陽電子消滅の項)" 丸善, 3

谷川昭一郎等人：《应用物理手册（正电子湮灭部分）》丸善，3

A. Uedono: "A Detection of Helium Implanted into Nickel by Slow Positrons" Phys. Lett. A.

A. Uedono：“通过慢速正电子检测氦注入镍” Phys。