Derivative-based analysis for temperature and pressure evolution of dielectric relaxation times in vitrifying liquids.

TLDR: The derivative-based analysis for detecting regions of the validity of the Vogel-Fulcher-Tammann (VFT) dependence for superpressed and supercooled liquids is discussed and the relation between the derivative based behavior mentioned above and the apparent activation enthalpy (temperature path) or the apparentactivation volume (pressure path) is indicated.

Abstract: The derivative-based analysis for detecting regions of the validity of the Vogel-Fulcher-Tammann VFT dependence for superpressed and supercooled liquids is discussed. For the temperature T path the analysis introduced by Stickel et al. J. Chem. Phys. 104, 2043 1996; 107, 1086 1997 is recalled. For the pressure P path the derivation based on the counterpart of the VFT dependence proposed in Paluch et al. J. Phys.: Condens. Mater 10, 4131 1998 is presented. The appearance of two ideal glass temperatures T0 or pressures P0, fragility strength coefficients DT,DP, and prefactors 0 , 0 for VFT equations in following dynamical domains, i.e., high-temperature Thigh and low-temperature Tlow or low-pressure Plow and high-pressure Phigh, is stressed. It is noteworthy that the values of T0ThighT0Tlow,DTThigh DTTlow, and 0 Thigh0 Tlow. Analogous behavior was noted for isothermal PL and PH dynamic domains. A similar derivative-based approach is also applied to test the validity of the mode coupling