Origin of Semiconducting Behavior of CaO Added BaTiO_3-(Bi_(1/2)Na_(1/2))TiO_3 Ceramics

摘要

An effect of addition of CaO on electrical resistivity in BaTiO_3-(Bi_(1/2)Na_(1/2))TiO_3 (BT-BNT) solid solution ceramics was investigated. Three kinds of CaO adding processes were applied. Extra CaO additive against stoichiometric composition is effective to give semiconductive property into the BT-BNT ceramics. However, the ceramics with CaO-inclusive composition such as Ba_(0.9)(Bi_(0.5)Na_(0.15)Ca_(0.35))_(0.1) TiO_3 had a high resistivity. From chemical composition analysis and structure analysis, it was concluded that Ca~(2+) dominantly substituted for Na~+ in the A site of perovskite-type ABO_3 structure and then that residual Bi~(3+) acts a donor.