Observation of indentation-induced shear bands in a metal-organic framework glass
Observation of indentation-induced shear bands in a metal-organic framework glass
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DOI：
10.1073/pnas.2000916117
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发表时间：
2020-05-12
影响因子：
11.1
通讯作者：
Yue, Yuanzheng
中科院分区：
文献类型：
--
作者：
Stepniewska, Malwina;Januchta, Kacper;Yue, Yuanzheng
金属有机框架（MOF）玻璃是一种新兴的熔融淬火玻璃。最近，人们在mof的一个子集——沸石咪唑盐框架（zif）中发现了一些有趣的特性，如超高玻璃形成能力和低液体脆性。然而，对ZIF玻璃的断裂行为尚未进行研究。在这里，我们报告了在具有代表性的熔融淬火ZIF玻璃，即ZIF-62玻璃(zni （1.68)bIm(0.32)）中观察到的裂纹模式和由压痕引起的剪切带。ZIF玻璃中的剪切带与其他类型的完全聚合玻璃的开裂行为形成强烈对比，这些玻璃在压痕下不表现出任何剪切带。我们将这种异常开裂行为归因于ZIF玻璃中的配位键（Zn-N）容易断裂，因为这些键比网络玻璃中的离子和共价键弱得多。
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.