To Theany, Sørensen Søren S, Stepniewska Malwina, Qiao Ang, Jensen Lars R, Bauchy Mathieu, Yue Yuanzheng, Smedskjaer Morten M
Department of Chemistry and Bioscience, Aalborg University, DK-9220, Aalborg, Denmark.
Department of Materials and Production, Aalborg University, DK-9220, Aalborg, Denmark.
Nat Commun. 2020 May 22;11(1):2593. doi: 10.1038/s41467-020-16382-7.
Metal-organic framework glasses feature unique thermal, structural, and chemical properties compared to traditional metallic, organic, and oxide glasses. So far, there is a lack of knowledge of their mechanical properties, especially toughness and strength, owing to the challenge in preparing large bulk glass samples for mechanical testing. However, a recently developed melting method enables fabrication of large bulk glass samples (>25 mm) from zeolitic imidazolate frameworks. Here, fracture toughness (K) of a representative glass, namely ZIF-62 glass (Zn(CHN)(CHN)), is measured using single-edge precracked beam method and simulated using reactive molecular dynamics. K is determined to be ~0.1 MPa m, which is even lower than that of brittle oxide glasses due to the preferential breakage of the weak coordinative bonds (Zn-N). The glass is found to exhibit an anomalous brittle-to-ductile transition behavior, considering its low fracture surface energy despite similar Poisson's ratio to that of many ductile metallic and organic glasses.
与传统的金属玻璃、有机玻璃和氧化物玻璃相比，金属有机框架玻璃具有独特的热性能、结构性能和化学性能。到目前为止，由于制备用于机械测试的大块玻璃样品存在挑战，人们对它们的机械性能，特别是韧性和强度缺乏了解。然而，最近开发的一种熔化方法能够从沸石咪唑酯骨架制备大块玻璃样品（>25毫米）。在此，使用单边预裂纹梁法测量了一种代表性玻璃（即ZIF-62玻璃（Zn(CHN)(CHN)））的断裂韧性（K），并使用反应分子动力学进行了模拟。确定K约为0.1 MPa m，由于弱配位键（Zn-N）的优先断裂，其甚至低于脆性氧化物玻璃。尽管该玻璃的泊松比与许多韧性金属玻璃和有机玻璃相似，但其断裂表面能较低，因此表现出异常的脆韧转变行为。
