title: Communication: Enthalpy relaxation in a metal-organic zeolite imidazole framework (ZIF-4) glass-former.
abstract: Amorphization in metal-organic framework materials initiated by the collapsed crystal offers new access to glasses; however, the understanding of such glasses remains to be clarified. Here, we studied the glass transition thermodynamics and kinetics in a zeolitic imidazolate framework ZIF-4 utilizing enthalpy relaxation measurements. The calorimetric glass transition profile and relaxation behaviors in ZIF-4 are found to reproduce the basic features and correlations manifested by conventional melt-quenched glasses. A comparison with various melt-quenched glasses suggests that the low fragility of ZIF-4 is ascribed to the low thermal-pressure coefficient due to the directional tetrahedral bond, partly leading to the low vibrational entropy in the melt-crystal entropy difference.
authors.forename: Di
authors.initials: D
authors.lastname: Xu
authors.forename: Yingdan
authors.initials: Y
authors.lastname: Liu
authors.forename: Yongjun
authors.initials: Y
authors.lastname: Tian
authors.affiliation: State Key Laboratory of Metastable Materials Science and Technology, and College of Materials Science and Engineering, Yanshan University, Qinhuangdao, Hebei 066004, China.
authors.forename: Li-Min
authors.initials: LM
authors.lastname: Wang