Glass Transition in Binary Eutectic Systems: Best Glass-Forming Composition

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• 作者：Li-Min Wang ; Zijing Li ; Zeming Chen ; Yue Zhao ; Riping Liu ; Yongjun Tian
• 刊名：Journal of Physical Chemistry B
• 出版年：2010
• 出版时间：September 23, 2010
• 年：2010
• 卷：114
• 期：37
• 页码：12080-12084
• 全文大小：270K
• 年卷期：v.114,no.37(September 23, 2010)
• ISSN：1520-5207

文摘

The glass transition and glass-forming ability in a binary eutectic system of methyl o-toluate (MOT) versus methyl p-toluate (MPT) are studied across the whole composition range. The phase diagram is constructed to explore the best glass-forming composition as the characteristic temperatures of the glass transition, crystallization, eutectic, and liquidus are determined. The best vitrification region is found to locate between the eutectic and the midpoint compositions of the eutectic line, indicating a remarkable deviation from the eutectic composition. The compilation of various simple binary eutectic systems covering inorganic, metallic, ionic, and molecular glass-forming liquids reproduces the rule. Kinetics and thermodynamics in binary systems are investigated to associate with the rule. The composition dependence of the structural relaxation time and the kinetic fragility are presented with dielectric measurements. It is found that whereas mixing of binary miscible liquids kinetically favors glass formation, thermodynamic contribution to the deviation of the best glass-forming composition from eutectics is implied.