Study of layered structured ferroelectric materials grown by laser ablation

Abstract

Layered structured ferroelectric thin films of different compounds were deposited by excimer laser ablation process. SrBi₂Nb₂O₉ was here chosen as the initial compound. The remnant and spontaneous polarization in pure SrBi₂Nb₂O₉ thin film were found to be 6 µ C/cm² and 15 μ C/cm² respectively. The dielectric constant was 220 at 100 kHz. In the films, the usual 'B' site cation, 'Nb⁺²' replaced 'Ta⁺²' partially. Different parameters were chosen during deposition, which in turn controlled the Sr⁺²/Ta⁺⁵ ratio. It was seen that the extent of crystallinity and the microstructure depends upon the amount of 'Sr⁺²' present in the compound. The dielectric and the conduction properties were studied as a function of the cation (Ta⁺²/Nb⁺²) ratio in the 'B' site, to study the coupling phenomenon.