Thermodynamic study of simple molecular glasses: universal features in their heat capacity and the size of the cooperatively rearranging regions.
Thermodynamic study of simple molecular glasses: universal features in their heat capacity and the size of the cooperatively rearranging regions.
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DOI：
10.1103/physrevlett.109.045701
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发表时间：
2012-07
影响因子：
8.6
通讯作者：
S. Tatsumi;S. Aso;O. Yamamuro
中科院分区：
文献类型：
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作者：
S. Tatsumi;S. Aso;O. Yamamuro
得到了分子液体玻璃化转变的一些普遍热力学性质。用新研制的绝热量热计测定了气相沉积法玻璃化丙烯的热容C（p）。丙烯的玻璃化转变温度最低（T（g）=56 K），在T（g）处C（p）跃变最大（C（p）（lq）/C（p）（gl）~2.5），剩余熵（S（res）~ Rln 2）最低。我们用液体淬火玻璃化的其它烃分子分析了目前的数据，并得到以下结果：（1）用Kauzmann温度T（K）可以很好地标定过剩热容。（2）冻结在T（g）处的协同重排区（CRR）的大小随T（g）和T（K）之间温差的减小而增大。（Kauzmann温度），和（3）分子越简单，冷冻CRR变得越大。这些都支持亚当-吉布斯理论的有效性。
We have obtained some universal thermodynamic properties on glass transitions of molecular liquids. The heat capacity C(p) of glassy propene, which was vitrified by using a vapor-deposition technique, was measured with a newly developed adiabatic calorimeter. Propene has the lowest glass transition temperature (T(g)=56 K), the largest C(p) jump at T(g) (C(p)(lq)/C(p)(gl)~2.5), and the lowest residual entropy (S(res)~Rln2) compared with glass-forming molecules measured before. We have analyzed the present data with other hydrocarbon molecules vitrified by liquid quenching and obtained the following results: (1) The excess heat capacities are scaled well by using a Kauzmann temperature T(K), (2) The size of the cooperative rearrangement region (CRR) frozen at T(g) increases with decreasing the temperature difference between T(g) and T(K) (Kauzmann temperature), and (3) The simpler the molecule is, the larger the frozen CRR becomes. These are all supporting the validity of the Adam-Gibbs theory.