Effects of excess Bi2O3 on the ferroelectric behavior of Nd-doped Bi4Ti3O12 thin films

Abstract

Effects of excess Bi2O3 content on formation of (Bi3.15Nd0.85)-Ti3O12 (BNT) films deposited by RF sputtering were investigated. The microstructures and electrical properties of BNT thin films are strongly dependent on the excess Bi 2O3 content and post-sputtering annealing temperature, as examined by XRD, SEM, and P-E hysteresis loops. A small amount of excess bismuth improves the crystallinity and therefore polarization of BNT films, while too much excess bismuth leads to a reduction in polarization and an increase in coercive field. P-E loops of well-established squareness were observed for the BNT films derived from a moderate amount of Bi2O3 excess (5 mol%), where a remanent polarization 2Pr of 25.2 μC/cm 2 and 2Ec of 161.5 kV/cm were shown. A similar change in dielectric constant with increasing excess Bi2O3 content was also observed, with the highest dielectric constant of 304.1 being measured for the BNT film derived from 5 mol% excess Bi2O3.