Fluorite-to-Aurivillius phase transformation kinetics in sol-gel derived SBT thin films

SBT films with different thickness were fabricated using a sol-gel processing and spin coating. The as-coated films were heated at 600 °C for the crystallization to fluorite and then further heated at 740-770 °C for the phase transformation to Aurivillius. It was found that the phase transformation kinetics apparently increased with thickness up to ∼390 nm, and then it decreased above this value. The Johnson-Mehl-Avrami (JMA) isothermal kinetics analyses showed the dependence of nucleation and crystal growth modes on the film thickness. From the Arrhenius plots the activation energy values for the phase transformation were determined for SBT films with different thickness.