• Topological defects in crystals: A density-wave theory

• # Fulltext

https://www.ias.ac.in/article/fulltext/boms/010/01-02/0045-0051

• # Keywords

Dislocations; core energy and structure; topological defects in crystals; density wave theory

• # Abstract

A new approach for describing dislocations and other topological defects in crystals, based on the density wave theory of Ramakrishnan and Yussouff is presented. Quantitative calculations are discussed in brief for the order parameter profiles, the atomic configuration and the free energy of a screw dislocation with Burgers vector$$\overset{\lower0.5em\hbox{\smash{\scriptscriptstyle\rightharpoonup}}} {b} = (a/2, a/2,a/2 )$$ in a bcc solid. Our results for the free energy of the dislocation in a crystal of sizeR, when expressed as (λb2/4π) ln (αR/|b|) whereλ is the shear elastic constant, yield, for example, the valueα ⋍ 1·85 for sodium at its freezing temperature (371°K). The density distribution in the presence of the dislocation shows that the dislocation core has a columnar character. To our knowledge, this study represents the first calculation of dislocation structure, including the core, within the framework of an order parameter theory incorporating thermal effects.

• # Author Affiliations

1. Department of Physics, Indian Institute of Science, Bangalore - 560 012, India

• # Bulletin of Materials Science

Volume 44, 2021
All articles
Continuous Article Publishing mode

• # Dr Shanti Swarup Bhatnagar for Science and Technology

Posted on October 12, 2020

Prof. Subi Jacob George — Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bengaluru
Chemical Sciences 2020