Rietveld refinement of barium titanate stannate crystal structure

Abstract

The barium titanates have wide application in electronic industry as a dielectric and ferroelectric materials.The BaTiO3 doped with Sn is important for practical application in ceramic capacitors as well as in functionally graded materials. It is known that BaTiO3 materials have the typical perovsikite crystal structural. Their ideal crystal structure is a centrosimetric cubic structure with space group. However, the changes in temperature, pressure, and composition lead to phase transitions and crystal structure transformations. Pm 3m in this study using by Rietveld refinement, we resolved crystal structure of barium titanate stannate (BTS) BaTi1−xSnxO3 (x = 0, 0.025, 0.05, 0.07, 0.10, 0.12, 0.15 and 0.20) solid solutions. The powders were prepared by simple solid state reaction at 1420 oC, in air for 2 hours. The structural investigations of the BTS samples were done at room temperature using an X-ray diffraction, Raman spectroscopy and TEM micrograph. The Rietveld refinement of the X-ray diffraction data was used to analyze the structural changes depending on amount of the Sn4+ ions in the BTS. Obtained data show that increasing of Sn amount in the structure provokes the transformation of crystal structure from tetragonal to cubic one. We suppose that the absence of orthorhombic and rhombohedral phases is probably a consequence of phase (0.025≤x<0.20) stabilization caused by method of sample preparation (high temperature solid state reaction).