Kinetics of non-isothermal cold crystallization in the antiferroelectric smectic phase of 3F5BFBiHex as seen by differential scanning calorimetry and broadband dielectric spectroscopy

The non-isothermal cold crystallization process from the antiferroelectric SmCA* phase of 3F5BFBiHex was studied by differential scanning calorimetry (DSC) and broadband dielectric spectroscopy (BDS) experiments in detail with various heating rates. DSC studies have revealed the complexity of the crystallization process. The use of the dielectric spectroscopy method allowed to describe the behavior of molecular I-process (reorientation molecules around the long axis) and collective (anti-phase phason) relaxation processes during cold crystallization. The amplitude of I-process decreases faster than the intensity of anti-phase phason process. The kinetics of nonisothermal crystallization process was analyzed in terms of Ozawa and Mo models. The use of the Ozawa model allowed to obtain the dimensionality parameter m and the crystallization constant rate Z. The energy barrier obtained using the Kissinger equation is almost the same in both DSC and BDS methods (51 kJ/mol). Energy barriers obtained by means of Augis-Bennett model for DSC data are around 10-20 kJ/mol smaller than those determined based on dielectric data. (C) 2020 Elsevier B.V. All rights reserved.

Automated summary

The non-isothermal cold crystallization process of 3F5BFBiHex from the antiferroelectric SmCA* phase was studied using DSC and BDS experiments. DSC studies showed the complexity of the crystallization process, while BDS method described the behaviors of molecular I-process and collective anti-phase Phason relaxation processes. Energy barriers obtained from different models differed, but were close in DSC and BDS methods.