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arXiv 2012.07264cond-mat.dis-nn
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玻璃化转变表观活化能的解释

Interpretation of the apparent activation energy of glass transition

Koun Shirai

摘要:

玻璃粘度的温度依赖性是玻璃研究领域的主要关注点。与阿克里乌斯定律的强烈偏离使得活化能的解释变得困难。在本研究中,一个合理的解释的表观活化能被证明沿着类似的线在固态物理和化学。与普遍认为玻璃中的相变发生在根据Vogel-Fulcher-Tammann公式的参考温度$T_{0}$的观点相反,在本工作中,在玻璃化转变温度$T_{g}$观察到的转变被认为是从液相到固相的相变。玻璃的一个显著特征是能垒在转变范围内随宽度$ΔT_{g}$而显著变化。能量势垒的这种变化改变了表观活化能构成阿耳忒弥斯形式的方式。现有的实验数据的分析表明,实际的能量势垒是显着小于表观活化能,重要的是,所获得的值是在合理的范围内的预期的化学键的能量。表观活化能的高估取决于比率$T_{g}/ΔT_{g}$,这解释了两种类型的玻璃强和脆玻璃的存在。脆性可以被重新解释为当从高温接近$T_{g}$时能垒增加程度的指示。由于在$T_{g}$以下没有观察到粘度的差异,因此在$T_{0}$处不太可能发生转变。

英文摘要:

The temperature dependence of the viscosity of glass is a major concern in the field of glass research. Strong deviations from the Arrhenius law make the interpretation of the activation energy difficult. In the present study, a reasonable interpretation of the apparent activation energy is demonstrated along similar lines as those adopted in solid-state physics and chemistry. In contrast to the widely held view that phase transition in glass occurs at the reference temperature $T_{0}$ according to the Vogel--Fulcher--Tammann formula, in the present work the transition observed at the glass-transition temperature $T_{g}$ is regarded as a phase transition from the liquid to solid phases. A distinct feature of glass is that the energy barrier significantly changes in the transition range with width $ΔT_{g}$. This change in the energy barrier alters the manner in which the apparent activation energy constitutes the Arrhenius form. Analysis of available experimental data showed that the actual energy barrier is significantly smaller than the apparent activation energy, and importantly, the values obtained were in the reasonable range of energy expected for chemical bonds. The overestimation of the apparent activation energy depends on the ratio $T_{g}/ΔT_{g}$, which explains the existence of two types of glasses strong and fragile glasses. The fragility can be re-interpreted as an indication of the degree of increase in the energy barrier when approaching $T_{g}$ from high temperatures. Since no divergence in viscosity was observed below $T_{g}$, it is unlikely that a transition occurs at $T_{0}$.

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