Effect of Sn2+ Ion Substitution on Dielectric Properties of (Ba,Ca)TiO3 Ferroelectric Ceramics

In this study, we investigated the sintering atmosphere dependence of the electric properties of Sn-doped (Ba0.82Ca0.13)TiO3 ceramics to clarify the effect of Sn2+ ions. The temperature of the dielectric constant peak for Sn-doped (Ba0.82Ca0.13)TiO3 ceramics sintered in a low P(O2) (1×10-11 MPa) atmosphere is higher than that for the sample sintered in a high P(O2) (2×10-2 MPa) atmosphere. The remanent polarization and coercive field for the Sn-doped (Ba0.82Ca0.13)TiO3 ceramics sintered at low P(O2) (1×10-11 MPa) also increased compared with those of the sample sintered at high P(O2) (2×10-2 MPa) at room temperature. The low P(O2) sintering atmosphere for Sn-doped (Ba0.82Ca0.13)TiO3 ceramics leads to a high tetragonality and the existence of Sn2+ ions. In addition, by X-ray absorption spectroscopy, it was verified that Sn2+ ions occupy Ba2+ sites in the (Ba0.82Ca0.13)TiO3 ceramics. Consequently, it is concluded that the high ferroelectric-to-paraelectric phase transition temperature and the high remanent polarization on the ceramics originate from Sn2+ ions substituted for Ba2+ sites in Sn-doped (Ba0.82Ca0.13)TiO3 ceramics.