文章基本信息

标题：Generating gradient germanium nanostructures by shock-induced amorphization and crystallization
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作者：Shiteng Zhao ; Bimal Kad ; Christopher E. Wehrenberg 等
期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2017
卷号：114
期号：37
页码：9791-9796
DOI：10.1073/pnas.1708853114
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Gradient nanostructures are attracting considerable interest due to their potential to obtain superior structural and functional properties of materials. Applying powerful laser-driven shocks (stresses of up to one-third million atmospheres, or 33 gigapascals) to germanium, we report here a complex gradient nanostructure consisting of, near the surface, nanocrystals with high density of nanotwins. Beyond there, the structure exhibits arrays of amorphous bands which are preceded by planar defects such as stacking faults generated by partial dislocations. At a lower shock stress, the surface region of the recovered target is completely amorphous. We propose that germanium undergoes amorphization above a threshold stress and that the deformation-generated heat leads to nanocrystallization. These experiments are corroborated by molecular dynamics simulations which show that supersonic partial dislocation bursts play a role in triggering the crystalline-to-amorphous transition.
关键词：amorphization ; laser shock ; nanocrystallization ; germanium ; gradient materials