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首页> 外文期刊>Journal of Non-Crystalline Solids: A Journal Devoted to Oxide, Halide, Chalcogenide and Metallic Glasses, Amorphous Semiconductors, Non-Crystalline Films, Glass-Ceramics and Glassy Composites >The residual configurational entropy below the glass transition: Determination for two commercial optical glasses
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The residual configurational entropy below the glass transition: Determination for two commercial optical glasses

机译：玻璃化转变温度以下的残留构型熵：两种商用光学玻璃的测定

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摘要

Essentially from differential scanning calorimetry and viscosimetry, the residual configurational entropy below the glass transition is determined for two linearly cooled commercial optical glasses, K7~TM and N_LaK12~TM from SCHOTT. The procedure is according to the conventional understanding of glass entropy and the conventional description of the configurational state by a distribution of fictive temperatures. For a cooling rate of 10 K/min, the residual entropy values found below the glass transition are 0.146 J/ (g K) for K7~TM and 0.148 J/(g K) for N-LaK12~TM. The result is discussed comparing with both the lower limit for the residual entropy resulting from the reversibly exchanged heat (f dq/T, 'Clausius limit') and the upper limit given by the configurational entropy of an equilibrium liquid with the same fictive temper_ature. The difference between the residual entropy and its lower limit is equal to the entropy generation due to the fall-out from equilibrium during linear cooling. The difference between the residual entropy and its upper limit is the driving force of the crossover- (or Kovacs-) effect. It turns out that the difference between the residual entropy and the Clausius limit is very small. The values found amount to less than 0.0001 J/(g K) for both glasses. Therefore, this difference can be neglected concerning the extrapolation of the Adam-Gibbs relation to low temperatures.
机译：基本上从差示扫描量热法和粘度测定法，可以确定两种线性冷却的商用光学玻璃（肖特的K7〜TM和N_LaK12〜TM）在玻璃化转变温度以下的残留构型熵。该过程是根据对玻璃熵的常规理解以及通过虚拟温度的分布对构型状态的常规描述。对于10 K / min的冷却速率，对于K7〜TM，在玻璃化转变以下发现的残余熵值为0.146 J /（g K），对于N-LaK12〜TM，则为0.148 J /（g K）。将讨论结果与可逆交换热量产生的残余熵的下限（f dq / T，“克劳修斯极限”）和具有相同虚拟温度的平衡液体的构型熵给出的上限进行比较。残余熵及其下限之间的差异等于线性冷却过程中由于平衡失衡而产生的熵。残余熵及其上限之间的差异是交叉效应（或Kovacs效应）的驱动力。事实证明，残留熵和克劳修斯极限之间的差异很小。两种玻璃的发现值均小于0.0001 J /（g K）。因此，在将Adam-Gibbs关系与低温进行外推时，可以忽略这种差异。

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