Crystal structure and ferroelectric property of Bi4Si3O12-added Bi4−xSmxTi3O12

We synthesized Bi4−xSmxTi3O12 (x=0.55, 0.65, 0.80) and y mol% Bi4Si3O12-added Bi4−xSmxTi3O12 (x=0.65; y=5, 10, 15, 20) by a solid-state reaction, and investigated a relationship between the ferroelectric properties and crystal structures in these samples. From the P–E hysteresis measurements, it was clarified that the Bi3.35Sm0.65Ti3O12 showed better ferroelectric properties than the others with different Sm content, and the sample began to exhibit larger remanent polarization by adding Bi4Si3O12. In order to examine an effect of the Bi4Si3O12-addition from a structural point of view, we measured synchrotron X-ray diffractions of the samples at room temperature and 1000 K, and analyzed their crystal and electronic structures with the Rietveld technique and the maximum entropy method. As a result, it was suggested that the Bi4Si3O12-addition made distortions of the Ti-O6 octahedra larger and had an effect on the TiO bond strengths.

► A remanent polarization of Bi3.35Sm0.65Ti3O12 became larger by adding Bi4Si3O12(BSO).
► Rietveld analyses indicated higher distortions of TiO6 octahedra by the BSO addition.
► MEM analyses implied that the addition affected the electron density in the crystal.