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

Abstract

The non-isothermal cold crystallization process from the antiferroelectric SmC*A 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 l-process (reorientation molecules around the long axis) and collective (anti-phase phason) relaxation processes during cold crystallization. The amplitude of l-process decreases faster than the intensity of anti-phase phason process. The kinetics of non-isothermal 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.