Disordered off-center direction of Ti4+ in pseudo-cubic type BaTiO3 prepared by mixed hydroxide process

Akihisa AIMI, Keisuke HORIUCHI, Yuki YAMAGUCHI, Shigeru ITO, Kenjiro FUJIMOTO
2021 Journal of the Ceramic Society of Japan  
Recently, perovskite-type BaTiO 3 showing sharp X-ray diffraction peak comparable to that synthesized by a conventional solid-state reaction was obtained by mixing Ba(OH) 2 and TiO 2 hydrous gel and by leaving the mixture at 323 K or less. However, the obtained BaTiO 3 was cubic crystal system, which was different from that synthesized by a conventional solid-state reaction. In this study, the structural analysis of cubic-BaTiO 3 obtained by this technique was conducted, and the factors to form
more » ... cubic structure were investigated. Since no second harmonic generation signal was observed, the structure of BaTiO 3 was essentially different from that of traditional tetragonal-BaTiO 3 . Rietveld analysis with the initial structure model of ideal cubic perovskite structure exhibited that Ti 4+ had exceptionally large isotropic atomic displacement parameter. A reasonable isotropic atomic displacement parameter was obtained by considering the static site disorder in the initial structural model, that is, Ti 4+ locates at off-center position in TiO 6 octahedron by displacing in a disordered direction, resulting in pseudo-cubic symmetry.
doi:10.2109/jcersj2.20147 fatcat:qmajg2fvdneyphm3qj5q2h7ko4