Polymerizable complex synthesis of lead-free ferroelectric Na0.5Bi0.5TiO3 suppressing evaporation of sodium and bismuth

We present the results of experiments that assess the viability of the polymerizable complex method to synthesize sodium bismuth titanate Na0.5Bi0.5TiO3 (NBT) while preventing sodium and bismuth from evaporating. To synthesize NBT with the stoichiometric composition and no sodium and bismuth deficiencies, it is of vital importance to direct our attention to preventing the evaporation of sodium and bismuth, which can easily occur in high-temperature sintering. X-ray diffraction (XRD) and thermogravimetry-differential thermal analysis (TG-DTA) of precursors synthesized by the polymerizable complex method revealed a crystallization temperature located at a temperature between 300 and 400 degrees C. The C-13 NMR results show the peak intensity derived from residual organics decreased with an increase in the calcining temperature. The complete single phase in NBT was obtained at a temperature higher than 600 degrees C. From ferroelectric hysteresis loops, values of the remanent polarization were larger for the samples synthesized by the polymerizable complex method than for those by the solid-state reaction method. This result indicates that the NBT samples synthesized by the polymerizable complex method retain their stoichiometric compositions even if they are calcined at high temperatures below the melting point of NBT, which is supported by the results of Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES). (C)2015 The Ceramic Society of Japan. All rights reserved.