New intergrowth Bi2WO6-Bi3TaTiO9 ferroelectrics

Abstract

A new intergrowth bismuth layer-structured ferroelectric, Bi2WO6-Bi3TaTiO9 (BW-BTT), was successfully synthesized by solid-state reaction, and the regular intergrowth structure was confirmed by the Rietveld method. Differential thermal analysis measurements suggested that the BW-BTT underwent ferroelectric phase transitions twice at around the Curie temperatures of the constituent compounds of BW and BTT. The structural analysis of the BW-BTT showed that there are two kinds of Bi ions in the bismuth oxide layers, and that one Bi ion was displaced the polarization direction by about 2% of the lattice constant a from the corresponding position in the parent tetragonal structure. This displacement of Bi in the bismuth oxide layers is the structural feature which was found for the first time for both conventional and intergrowth bismuth layered structures.