Sr_<1-x>Bi_<2+x>Ta_2O_<9-δ>(x=0, 0.2)強誘電体の結晶構造と強誘電特性に及ぼす熱処理の影響

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Ferroelectric material of SrBi_2Ta_2O_9 consists of (Bi_2O_2)^<2+> layer and peseudoperovskite block, (SrTa_2O_7)^<2->. The crystal structure, defect, oxygen nonstoichiometory, and ferroelectric properties change by heat treatment. In this study, we investigated the relation between crystal structure, physical properties and ferroelectric properties by various heat treatment of Sr_<1-x>Bi_<2+x>Ta_2O_<9-δ> (x= 0, 0.2). From the results, the remanent polarization (P_r) and coercive field (E_c) increase by heat treatment at x= 0. On the other hand, P_r is almost constant and E_c decreased with heat treatment of oxidation direction at x= 0.2. The dielectric constant (ε_s) increase with heat treatment of oxidation direction and Curie temperature (T_C) decrease by heat treatment at x= 0. On the other hand, ε_s decreased with heat treatment of oxidation direction and T_C decrease by heat treatment at x= 0.2. From the results of structural analysis by the Rietveld method using the neutron powder diffraction data, we concluded that the distortion of (Bi_2O_2)^<2+> layer and TaO_4 plane, and tilting angle of TaO_6 octahedra on a-c plane affect E_c. The tilting angle of TaO_6 octahedra on b-c plane affects T_C.
社団法人日本セラミックス協会の論文
2002-09-01