Dependence of Crystal Structure and Ferroelectric Properties on Composition and Heat Treatment for Sr-Bi-Ta-Si-O Ferroelectric Material

Abstract

We investigated the relation between the crystal structure and ferroelectric properties of Bi₂SiO₅, Bi₄Si₃O₁₂ and Bi₂O₃-added Sr_0.8Bi_2.2Ta₂O₉. Moreover, we investigated that the effect of heat treatment using one of the Bi₄Si₃O₁₂ added Sr_0.8Bi_2.2Ta₂O₉ compounds after a vacuum and high pressure oxygen treatment. The remanent polarization(P_r) increased with the added Bi₄Si₃O₁₂ or Bi₂O₃, however, it decreased due to added Bi₂SiO₅. It was considered that the volume of the tetrahedrons, which makes the top of Bi, increased with the addition of Bi₂O₃ in the (Bi₂O₂)²⁺ layer, and the displacement of the atom becomes easy for the applied field due to the pseudo perovskite (SrTa₂O₇)^2- received stress. It was noted that the T_c decreased with the decreasing tilting angle(α_b) of the TaO₆ octahedron by heat treatment of the reduced direction.