Prevalence of approximate square root(t) relaxation for the dielectric alpha process in viscous organic liquids.
Prevalence of approximate square root(t) relaxation for the dielectric alpha process in viscous organic liquids.
复制标题
粘性有机液体中介电 α 过程普遍存在近似平方根 (t) 弛豫。
作者：
A. Nielsen;T. Christensen;B. Jakobsen;Kristine Niss;N. B. Olsen;R. Richert;J. Dyre
本文介绍了有机玻璃形成液体的介电弛豫数据汇编从不同的群体，并补充了新的测量。感兴趣的主要量是在双对数图中作为频率的函数绘制的α介电损耗的“最小斜率”，即，损耗峰值频率以上的数值最大斜率。由53种液体的347个光谱组成的数据显示出接近-1/2的最小斜率的普遍性，对应于短时间内介电弛豫函数的近似平方根（t）依赖性。本文研究了最小斜率与以下因素之间可能存在的相关性：（1）温度（通过损耗峰值频率量化）;（2）逆幂律与损耗峰值以上数据的拟合程度;（3）时间-温度叠加程度;（4）损耗峰值半宽;（5）偏离非Arrhenius行为;（6）损耗强度。对于前三个点，我们发现相关性表明液体的特殊状态，最小斜率接近-1/2。对于最后三个点，只发现相当不显著的相关性，除了具有最小斜率的大损失液体，其在数值上显著大于1/2。我们的结论是-不包括大损失的液体-近似平方根（t）松弛似乎是一个通用的属性的α松弛的有机玻璃形成。
This paper presents dielectric relaxation data for organic glass-forming liquids compiled from different groups and supplemented by new measurements. The main quantity of interest is the "minimum slope" of the alpha dielectric loss plotted as a function of frequency in a log-log plot, i.e., the numerically largest slope above the loss peak frequency. The data consisting of 347 spectra for 53 liquids show prevalence of minimum slopes close to -1/2, corresponding to approximate square root(t) dependence of the dielectric relaxation function at short times. The paper studies possible correlations between minimum slopes and (1) temperature (quantified via the loss peak frequency); (2) how well an inverse power-law fits data above the loss peak; (3) degree of time-temperature superposition; (4) loss peak half width; (5) deviation from non-Arrhenius behavior; (6) loss strength. For the first three points we find correlations that show a special status of liquids with minimum slopes close to -1/2. For the last three points only fairly insignificant correlations are found, with the exception of large-loss liquids that have minimum slopes that are numerically significantly larger than 1/2. We conclude that--excluding large-loss liquids--approximate square root(t) relaxation appears to be a generic property of the alpha relaxation of organic glass formers.