Unveiling the strong dependence of the alpha-relaxation dispersion on mixing thermodynamics in binary glass-forming liquids
Unveiling the strong dependence of the alpha-relaxation dispersion on mixing thermodynamics in binary glass-forming liquids
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揭示二元玻璃形成液体中 α 弛豫色散对混合热力学的强烈依赖性
DOI：
10.1039/d0cp06358d
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发表时间：
2021
影响因子：
3.3
通讯作者：
Wang Li-Min
中科院分区：
文献类型：
--
作者：
Liu Xin;Li Xudong;Wang Ji;Feng Shidong;Wang Li-Min
利用焓和介电弛豫测量研究了具有不同混合焓ΔHmix的二元分子玻璃形成混合物中的结构α-弛豫色散。本文通过测定非指数指数β，重点研究了弛豫色散对混合热力学的依赖关系及其组成依赖性。由焓弛豫和介电弛豫测定的β值吻合较好。值得注意的是，混合焓为正的体系（放热的，ΔHmix >0）对纯组分的两个β值进行线性平均时，β的组成依赖性有正偏差，而混合焓为负的体系（吸热的，ΔHmix <0）的β的组成依赖性有负偏差。此外，还讨论了非指数行为与混合熵之间的关系，揭示了β的组成依赖于混合的正或负偏差都伴随着相对于理想混合的过量熵的相同符号。
Structural α-relaxation dispersion in binary molecular glass forming mixtures with distinct mixing enthalpy ΔHmix was investigated using enthalpic and dielectric relaxation measurements across the entire composition range. This study focused on the dependence of the relaxation dispersion on the mixing thermodynamics by determining the non-exponential exponent β, and its composition dependence. The β values determined by the enthalpic and dielectric relaxations agree well. Remarkably, it is found that the systems with positive enthalpy of mixing (exothermic, ΔHmix >0) have positive deviations in the composition dependence of β from the linear averaging of the two β values of the pure components, while negative deviations are observed for the systems with negative enthalpy of mixing (endothermic, ΔHmix <0). Furthermore, the relation between the non-exponential behaviors and entropy of mixing is discussed, revealing that the positive or negative deviation of β in its composition dependence on mixing is accompanied by the same sign of the excess entropy of mixing relative to the ideal one.