New method for determining the thermal diffusion coefficient of thin films using ferroelectric crystals

A new method for determining the thermal diffusion coefficient of thin dielectric films deposited on a ferroelectric crystal detector is presented. The surface of the specimen was periodically heated by a rectangular modulated heat flow. The impact of the ratio of the film thickness to the detector thickness, as well as the film thermal diffusion coefficient on the shape of the system’s pyroelectric response is analyzed. Optimal conditions for the measurements are offered. Approbation of the method was carried out on an unannealed lead zirconate titanate (PZT) film deposited on a lithium tantalate crystal. The thermal diffusion coefficient of the specimen was α = 1.5 × 10⁻⁷ m²/s, which correlates with an independent estimation of this magnitude for polarized films.