We explore the concept of correlative activation free energy (CAFE) for the analysis and interpretation of viscosity data of a collection of 847 inorganic oxide glass formers that exhibit various degrees of non-Arrhenius behavior. The CAFE model formalism is strictly based on transition state theory and accounts for the variation in the activation barrier height for the viscous dissipation due to the structural evolution the system undergoes upon traversing the glass transition regime. Thus, fitting parameters are meaningful in a statistical thermodynamic context. Compared to the VFT and MYEGA equations, fits using the CAFE model are more robust when extrapolating to infinite temperature because the latter encodes non-enthalpic contributions to the rate coefficient more realistically. The CAFE model-based analysis reveals a strong connection between melt fragility and the degree of change in the potential energy landscape with temperature. Accordingly, while the average ground-state potential energy of the glass forming liquid gradually increases with temperature, the energy of the activated state remains relatively invariant. Our analysis also allows one to estimate the number of atoms involved in the viscous relaxation process, which ranges from approximately 10 to 50 atoms for the oxide glass formers studied. We observe that thermally activated dynamic phenomena exhibited by glassy networks, such as the mixed alkali effect, persist into the supercooled liquid state.

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相关活化自由能 （CAFE） 模型：在无机氧化物玻璃成型剂中的粘性工艺中的应用


我们探索了相关活化自由能 （CAFE） 的概念，用于分析和解释 847 种表现出不同程度非 Arrhenius 行为的无机氧化物玻璃形成剂的粘度数据。CAFE 模型形式严格基于过渡态理论，并考虑了由于系统在穿越玻璃过渡态时经历的结构演变而导致的粘性耗散的活化势垒高度的变化。因此，拟合参数在统计热力学背景下是有意义的。与 VFT 和 MYEGA 方程相比，使用 CAFE 模型的拟合在外推到无限温度时更加稳健，因为后者更真实地编码了对速率系数的非焓贡献。基于 CAFE 模型的分析揭示了熔体脆性与势能景观随温度变化的程度之间的密切联系。因此，虽然玻璃成型液的平均基态势能随着温度的增加而逐渐增加，但活化态的能量保持相对不变。我们的分析还允许估计粘性弛豫过程中涉及的原子数，对于所研究的氧化物玻璃形成剂，范围约为 10 到 50 个原子。我们观察到玻璃网络表现出的热激活动力学现象，例如混合碱效应，持续到过冷液态。