Bennett, T.D.

Yue, Yuanzheng

Zhou, Chao

English

PosterProc-SR-BosonThermodynamic features and sub-Tg enthalpy relaxation in a melt-quenched metal-organic framework glass - ZIF-62Zhou, Chao1, Bennett, T. D.2, Yue, Y. Z.1(1) Department of Chemistry and Bioscience, Aalborg University, Frederik Bajers Vej 7H, DK-9220 Aalborg, Denmark; (2) Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, CB3 0FS Cambridge, UKPresenting Author’s E-mail Address: czh@bio.aau.dk (​mailto:czh@bio.aau.dk​)Metal-organic frameworks (MOFs) have been extensively investigated in recent decades because of their multi-functionalities for applications such as gas absorption, catalysis and sensing. Recent discoveries have shown that certain types of zeolitic imidazolate frameworks (ZIFs), a subset of MOFs, could be vitrified upon quenching.[1-3] Study of this new family of glasses would give new angles to understand fundamental glass problems such as glass formation, glass transition, and glass relaxation. In the present work, we explore the thermodynamic evolution upon heating to melting point (Tm) in a melt-quenched metal-organic framework glass, namely, ZIF-62 [Zn(Im)1.75(bIm)0.25] glass, and its enthalpy relaxation. The temperature dependence of the difference in Gibbs free energy between ZIF-62 liquid and crystal in the range of temperature from glass transition temperature (Tg) to Tm is found to be weaker than that of metallic glasses. Owing to its small thermodynamic driving force for crystallization, ZIF-62 glass is rather stable against crystallization. We have found a striking feature for the enthalpy relaxation in the ZIF-62 glass, i.e., a wide range of the stretched exponent β of relaxation function for various sub-Tg annealing temperatures, compared to metallic and oxide glasses. The wide β range suggests a high degree of structural heterogeneity in ZIF-62 glass.References1.	Bennett, T. D., Tan, J. C., Yue, Y. Z., Baxter, E., Ducati, C., Terrill, N. J., Yeung, H. H. M., Zhou, Z., Chen, W., Henke, S., Cheetham, A. K., Greaves, G. N., Hybrid glasses from strong and fragile metal-organic framework liquids, Nature Communications. 6, 8079 (2015).2.	Bennett, T. D., Yue, Y. Z., Li., P., Qiao., A., Tao., H. Z., Greaves, G. N., Richard., T., Lampronti, G. I., Redfren, S. A. T., Blanc, F., Farha, O. K., Hupp, J. T., Cheetham, A. K., Keen, D. A., Melt-Quenched Glasses of Metal–Organic Frameworks, Journal of the American Chemical Society. 138, 3484-3492 (2016).3.	Tao, H. Z., Bennett, T. D., Yue, Y. Z., Melt-Quenched Hybrid Glasses from Metal–Organic Frameworks, Advanced Materials. 1601705 (2017).

Thermodynamic features and sub-Tg enthalpy relaxation in a melt-quenched metal-organic framework glass - ZIF-62

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Thermodynamic features and sub-Tg enthalpy relaxation in a melt-quenched metal-organic framework glass - ZIF-62

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