Mechanical quenching phenomenon in diamond

• 成果类型: Article
• 署名作者: Su, Zhengping; Duan, Yu; Tian, Yusong; Guo, Shukuan; Li, Penghui; Wang, Lin; Bu, Yeqiang; Nie, Anmin; Wang, Hongtao; Tian, Yongjun; Yang, Wei
• 署名单位: Zhejiang University; Suzhou Laboratory; Zhejiang University; Yanshan University
• 刊物名称: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• ISSN/ISSBN: 0027-12830
• DOI: 10.1073/pnas.2319663121
• 发表日期: 2024-04-02
• 关键词: electron localization; dislocation core; anvil cell; cathodoluminescence; strength; aluminum; silicon

摘要

The structure of dislocation cores, the fundamental knowledge on crystal plasticity, remains largely unexplored in covalent crystals. Here, we conducted atomically resolved characterizations of dislocation core structures in a plastically deformed diamond anvil cell tip that was unloaded from an exceptionally high pressure of 360 GPa. Our observations unveiled a series of nonequilibrium dislocation cores that deviate from the commonly accepted five- seven- membered ring dislocation core model found in FCC- structured covalent crystals. The nonequilibrium dislocation cores were generated through a process known as mechanical quenching, analogous to the quenching process where a high- energy state is rapidly frozen. The density functional theory-based molecular dynamic simulations reveal that the phenomenon of mechanical quenching in diamond arises from the challenging relaxation of the nonequilibrium configuration, necessitating a large critical strain of 25% that is difficult to maintain. Further electronic - scale analysis suggested that such large critical strain is spent on the excitation of valance electrons for bond breaking and rebonding during relaxation. These findings establish a foundation for the plasticity theory of covalent materials and provide insights into the design of electrical and luminescent properties in diamond, which are intimately linked to the dislocation core structure.