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Effect of Simultaneous Nucleation and Crystal Growth on DSC Crystallization Peaks of Glasses

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Author to whom correspondence should be addressed. e-mail: aluisio_cab@yahoo.com.br

Abstract

In this study, the change of the height of the crystallization peak, (δT)p, and the reciprocal of the crystallization peak temperature, 1/Tp, were investigated as a function of nucleation heat-treatment time for two silicate glasses: (2BaO·TiO2·2SiO2B2TS2) and lithium disilicate (Li2O·2SiO2LS2). Then, monolithic pieces were heat-treated in a differential scanning calorimetry furnace. The results demonstrated that these glasses behave similarly with respect to peak crystallization temperature, i.e., 1/Tp decreases with the heating rate for nucleation (φn). However, the results with B2TS2 samples demonstrated that (δT)p increases with rising heating rates for nucleation (shorter nucleation heat treatment times), φn, whereas (δT)p was found to decrease with φn in the LS2 specimens. This unexpected behavior is attributed to the extensive overlapping of the I(T) and U(T) curves shown by fresnoite glass.

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