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Title: Structure and energetics of nanotwins in cubic boron nitrides

Abstract

Recently, nanotwinned cubic boron nitrides (NT c-BN) have demonstrated extraordinary leaps in hardness. However, an understanding of the underlying mechanisms that enable nanotwins to give orders of magnitude increases in material hardness is still lacking. Here, using transmission electron microscopy, we report that the defect density of twin boundaries depends on nanotwin thickness, becoming defect-free, and hence more stable, as it decreases below 5 nm. Using ab initio density functional theory calculations, we reveal that the Shockley partials, which may dominate plastic deformation in c-BNs, show a high energetic barrier. We also report that the c-BN twin boundary has an asymmetrically charged electronic structure that would resist migration of the twin boundary under stress. These results provide important insight into possible nanotwin hardening mechanisms in c-BN, as well as how to design these nanostructured materials to reach their full potential in hardness and strength.

Authors:
;  [1];  [2];  [3];  [4];  [5];  [6]
  1. Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China)
  2. School of Materials Science and Engineering, and International Research Institute for Multidisciplinary Science, Beihang University, Beijing 100191 (China)
  3. Key Laboratory of Polar Materials and Devices, Ministry of Education, East China Normal University, Shanghai 200062 (China)
  4. National Institute for Materials Science, Tsukuba, Ibaraki 305-0044 (Japan)
  5. Nanostructures Research Laboratory, Japan Fine Ceramics Center, Nagoya 456-8587 (Japan)
  6. Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)
Publication Date:
OSTI Identifier:
22590518
Resource Type:
Journal Article
Journal Name:
Applied Physics Letters
Additional Journal Information:
Journal Volume: 109; Journal Issue: 8; Other Information: (c) 2016 Author(s); Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0003-6951
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; BORON NITRIDES; DENSITY; DENSITY FUNCTIONAL METHOD; ELECTRONIC STRUCTURE; HARDNESS; NANOSTRUCTURES; PLASTICITY; THICKNESS; TRANSMISSION ELECTRON MICROSCOPY

Citation Formats

Zheng, Shijian, Ma, Xiuliang, Zhang, Ruifeng, Huang, Rong, Taniguchi, Takashi, Ikuhara, Yuichi, Institute of Engineering Innovation, The University of Tokyo, Tokyo 113-8656, and Beyerlein, Irene J. Structure and energetics of nanotwins in cubic boron nitrides. United States: N. p., 2016. Web. doi:10.1063/1.4961240.
Zheng, Shijian, Ma, Xiuliang, Zhang, Ruifeng, Huang, Rong, Taniguchi, Takashi, Ikuhara, Yuichi, Institute of Engineering Innovation, The University of Tokyo, Tokyo 113-8656, & Beyerlein, Irene J. Structure and energetics of nanotwins in cubic boron nitrides. United States. https://doi.org/10.1063/1.4961240
Zheng, Shijian, Ma, Xiuliang, Zhang, Ruifeng, Huang, Rong, Taniguchi, Takashi, Ikuhara, Yuichi, Institute of Engineering Innovation, The University of Tokyo, Tokyo 113-8656, and Beyerlein, Irene J. 2016. "Structure and energetics of nanotwins in cubic boron nitrides". United States. https://doi.org/10.1063/1.4961240.
@article{osti_22590518,
title = {Structure and energetics of nanotwins in cubic boron nitrides},
author = {Zheng, Shijian and Ma, Xiuliang and Zhang, Ruifeng and Huang, Rong and Taniguchi, Takashi and Ikuhara, Yuichi and Institute of Engineering Innovation, The University of Tokyo, Tokyo 113-8656 and Beyerlein, Irene J.},
abstractNote = {Recently, nanotwinned cubic boron nitrides (NT c-BN) have demonstrated extraordinary leaps in hardness. However, an understanding of the underlying mechanisms that enable nanotwins to give orders of magnitude increases in material hardness is still lacking. Here, using transmission electron microscopy, we report that the defect density of twin boundaries depends on nanotwin thickness, becoming defect-free, and hence more stable, as it decreases below 5 nm. Using ab initio density functional theory calculations, we reveal that the Shockley partials, which may dominate plastic deformation in c-BNs, show a high energetic barrier. We also report that the c-BN twin boundary has an asymmetrically charged electronic structure that would resist migration of the twin boundary under stress. These results provide important insight into possible nanotwin hardening mechanisms in c-BN, as well as how to design these nanostructured materials to reach their full potential in hardness and strength.},
doi = {10.1063/1.4961240},
url = {https://www.osti.gov/biblio/22590518}, journal = {Applied Physics Letters},
issn = {0003-6951},
number = 8,
volume = 109,
place = {United States},
year = {Mon Aug 22 00:00:00 EDT 2016},
month = {Mon Aug 22 00:00:00 EDT 2016}
}