Yang, G.

Yue, Yuanzheng

Zhang, Y.F.

    Aalborg UniversitetDetection of structural heterogeneity in a hyperquenched silicate glassZhang, Y.F.; Yang, G.; Yue, YuanzhengPublication date:2015Document VersionPublisher's PDF, also known as Version of recordLink to publication from Aalborg UniversityCitation for published version (APA):Zhang, Y. F., Yang, G., & Yue, Y. (2015). Detection of structural heterogeneity in a hyperquenched silicateglass. Abstract from ICG Annual Meeting, Bangkok, Thailand.General rightsCopyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright ownersand it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.            ? Users may download and print one copy of any publication from the public portal for the purpose of private study or research.            ? You may not further distribute the material or use it for any profit-making activity or commercial gain            ? You may freely distribute the URL identifying the publication in the public portal ?Take down policyIf you believe that this document breaches copyright please contact us at vbn@aub.aau.dk providing details, and we will remove access tothe work immediately and investigate your claim.Downloaded from vbn.aau.dk on: April 30, 2017Detection of structural heterogeneity in a hyperquenched silicate glass Yanfei Zhanga, Guang Yangb, Yuanzheng Yuea,c   aKey Laboratory of Processing and Testing Technology of Glass & Functional Ceramics of Shandong Province, Qilu University of Technology, Jinan, 250353, P.R. China bElectronic Materials Research Laboratory, Key Laboratory of the Ministry of Education & International Center for Dielectric Research, Xi’an Jiaotong University, Xi’an 710049, China cSection of Chemistry, Aalborg University, Aalborg, DK-9220, Denmark  Keywords: Structural heterogeneity, Relaxation, Crystallization  The heterogeneous structure and dynamics in supercooled liquids and their glassy states is an important key to understand the nature of glass and glass transition. Here we study the structural heterogeneity in a ternary silicate glass using hyperquenching–annealing–calorimetry approach [1,2]. We observed two separated sub-Tg relaxation peaks on the calorimetric curve of the hyperquenched CaO–MgO–SiO2 glass, which have been attributed to two distinct structural domains of higher and lower potential energies, respectively. The higher energy domains in nanoscale are so unstable that they become ordered during hyperquenching. This is verified by the high-resolution transmission electron microscopy (HRTEM) images exhibiting ordered nanodomains in the glass matrix. Moreover, the nanoscale domains are further confirmed by the change of the lower temperature crystallization peak with sub-Tg annealing degree. The pre-ordered domains could lower the activation energy of crystal growth above Tg, and thus they remain stable during the sub-Tg annealing. But the higher temperature crystallization peak varies with the sub-Tg annealing degree, implying that the sub-Tg annealing affects only the lower energy domains, i.e., the disordered glass matrix. In addition, the higher energy domains during relaxation behave as a strong glass phase, whereas the lower energy domains do as a fragile one. It is found that silica crystals form at 1084 K for 4 hours, indicating the existence of the typical strong phase – silica in the supercooled magnesium-calcium silicate. It is also found that both silica and diopside form at 1084 K for 24 hours or at 1283 K for 2 hours, indicating the existence of the typical fragile phase – diopside. Therefore, the coexistence of the two types of local structures in the hyperquenched CaO–MgO–SiO2 glass is a clear manifestation of the structural heterogeneity in the supercooled liquid.   [1] Y. F. Zhang, G. Yang, Y. Z. Yue, Calorimetric signature of structural heterogeneity in a ternary silicate glass, J. Am. Ceram. Soc. 96 (2013) 3035-3037. [2] Y. F. Zhang, L. N. Hu, S. J. Liu, C. F. Zhu, Y. Z. Yue, Sub-Tg enthalpy relaxation in an extremely unstable oxide glass and its implication for structural heterogeneity, J. Non-Cryst. Solids 381 (2013) 23-28. 

Detection of structural heterogeneity in a hyperquenched silicate glass

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Detection of structural heterogeneity in a hyperquenched silicate glass

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