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标题：Observation of indentation-induced shear bands in a metal−organic framework glass
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作者：Malwina Stepniewska ; Kacper Januchta ; Chao Zhou 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：2020
卷号：117
期号：19
页码：10149-10154
DOI：10.1073/pnas.2000916117
出版社：The National Academy of Sciences of the United States of America
摘要：Metal−organic framework (MOF) glasses are a newly emerged family of melt-quenched glasses. Recently, several intriguing features, such as ultrahigh glass-forming ability and low liquid fragility, have been discovered in a number of zeolitic imidazolate frameworks (ZIFs) that are a subset of MOFs. However, the fracture behavior of ZIF glasses has not been explored. Here we report an observation of both cracking pattern and shear bands induced by indentation in a representative melt-quenched ZIF glass, that is, ZIF-62 glass (ZnIm 1.68 bIm 0.32 ). The shear banding in the ZIF glass is in strong contrast to the cracking behavior of other types of fully polymerized glasses, which do not exhibit any shear bands under indentation. We attribute this anomalous cracking behavior to the easy breakage of the coordinative bonds (Zn−N) in ZIF glasses, since these bonds are much weaker than the ionic and covalent bonds in network glasses.
关键词：metal−organic framework glass ; indentation ; cracking ; shear band ; hardness