Liu, S.J.

Tao, H.Z.

Yue, Yuanzheng

Zhang, Y.F.

    Aalborg UniversitetEstimation of critical cooling rates for nucleation in phosphosilicate glassesLiu, S.J.; Tao, H.Z.; Zhang, Y.F.; Yue, YuanzhengPublished in:The 24th International Congress on Glass - AbstractsPublication date:2016Document VersionPublisher's PDF, also known as Version of recordLink to publication from Aalborg UniversityCitation for published version (APA):Liu, S. J., Tao, H. Z., Zhang, Y. F., & Yue, Y. (2016). Estimation of critical cooling rates for nucleation inphosphosilicate glasses. In The 24th International Congress on Glass - Abstracts (pp. 266). InternationalCommission on Glass (ICG).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, 2017Estimation of critical cooling rates for nucleation in phosphosilicate glasses   Shujiang Liu1,2, Haizheng Tao1, Yanfei Zhang1,2, Yuanzheng Yue1,2,3*  1State Key Laboratory of Silicate Materials for Architectures, Wuhan University of Technology, Wuhan, Hubei 430070, China 2Key Laboratory of Processing and Testing Technology of Glass & Functional Ceramics of Shandong Province, Qilu University of Technology, Jinan 250353, China 3Department of Chemistry and Bioscience, Aalborg University, Aalborg DK-9000, Denmark  lsj-24@163.com    Crystallization of a liquid below the liquidus temperature is a complex process involving simultaneous nucleation and growth of crystallites.1) Nucleation is the crucial step of the whole crystallization process in liquid and determines the glass-forming ability. In most cases there exists a large temperature overlap between nucleation and crystal growth. It is known that The typical “TTT” diagram is used to measure critical cooling rate qc* of glass-forming liquids, and this is very time consuming and experimentally challenging. The determined qc* depends on the accuracy of determination of crystallinity and the resolution limit of the microscopic analyses. In this paper we attempt to derive a physical correlation between the cooling rate and nucleation, and to further obtain the qc* for glass formation from a liquid. We determine the critical cooling rates of some phosphosilicate liquids based on the differential scanning calorimetric (DSC) and viscometric measurements. The relation between the nucleation onset temperature and relatively low cooling rate can be obtained from DSC curves (Fig. 1). However, for the fast quenching process with larger cooling rate, the dependence of nucleation onset temperature on cooling rate is described by comparing both functions, (f1(T) and f2(T), which are derived from the classical nucleation theory (Fig. 2).2) f1(T) is cooling rate dependent, whereas f2(T) is independent on cooling rate. The crossover temperature above Tg for both curves corresponds to the nucleation onset temperature. Thus the qc* value is calculated at a crossover point between both f1(T) and f2(T) functions. The XRD results confirm the correlation between qc and nucleation onset temperature of slow- and fast-quenched samples. The qc of the fast quenched sample is determined from the relation between the cooling rate and the viscosity at fictive temperature. 3)   1) H. Yinnon, D. R. Uhlmann, Applications of thermoanalytical techniques to the study of crystallization kinetics in glass-forming liquids, Part I: Theory, J. Non-Cryst. Solids, 54, (1983) 253-275.  2) D. Becker, W. Döring. The kinetic treatment of nuclear formation in supersaturated vapors, Annalen der Physik, 24 (1935), 719-752. 3) Y. Z. Yue, R. von der Ohe, S. L. Jensen, Fictive temperature, cooling rate, and viscosity of glasses, J. Chem. Phys., 120 (2004), 8053-8059.    (a)                                                                            (b) 750 800 850 900 950 10000.81.21.62.02.430405060 Cp ( Jg-1K-1)T (K)20Cooling rate        (Kmin-1):   650 700 750 800 850 900 950-30-25-20-15-10-505932 936 940 944f2T (K)f1Tgcooling rate (Kmin-1):ln(   TT/qcT (K) 6050302040 a+b[TL(TL+T)2/T3  T2] Figure 1. CP curves of the glasses underwent various cooling rates.     Figure 2. Two temperature functions derived from  classical nucleation theory. Inset: nucleation onset temperatures with relatively low cooling rate.  

Estimation of critical cooling rates for nucleation in phosphosilicate glasses

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Estimation of critical cooling rates for nucleation in phosphosilicate glasses

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