Mn-doped (Bi0.5Na0.5) TiO3 thin film with low leakage current density and high ferroelectric performance

The films of (Bi0.5Na0.5)(Ti1-xMnx)O3-delta (BNTMx) were deposited on the substrates via the sol-gel method. The influence of the doping content of Mn on the microstructures and ferroelectric properties of the films were investigated. In addition, the valence states of Mn ions were analyzed. The results show that Mn ions have dissolved into the lattice of Bi0.5Na0.5TiO3 (BNT) without forming any secondary phase. When the doping content of Mn is 0.04, the film of BNTMx possesses a dense microstructure, maximum of remnant polarization (20.2 mu C center dot cm(-2)), minimum value of leakage current density (3.31 x 10(-5) A center dot cm(-2)), which shows good ferroelectric property and insulation performance. The results of XPS indicate that Mn ions exist in form of Mn2+, Mn3+ and Mn4+. The ratio of the amount of Mn4+ to that of Mn3+ and Mn2+ is 5.5:1. In this work, relationship between valence states of Mn ions and leakage current densities or ferroelectric property of the films were investigated in detail. The results will provide a new way for future applications of BNT-based multi-functional devices and an alternative for environmental-friendly ferroelectric materials.