Disordering of Metal-Organic Framework Crystals and Glasses upon Irradiation

Minerals tend to become disordered at the atomic scale when subjected to vitrification or irradiation. Recently, a subset of metal-organic frameworks (MOFs), e.g., the zeolitic imidazolate framework ZIF-4 (Zn[Im]2), can be vitrified into a glass state through melt-quenching. However, whether ZIF-4 can also reach a disordered state through irradiation remains poorly understood. Moreover, irradiation provides an extra degree of freedom to probe the relationship between structural disorder and mechanical properties in disordered MOFs. Therefore, we here perform simulated irradiation of both ZIF-4 crystals and glasses by reactive molecular dynamics simulations. We track the convergence of the two phases toward a new disordered state, with simultaneous evolution of both structure and mechanical properties. This study therefore helps to establish structure-property relations in forbidden glass states that are not accessible through any thermal path.