Enhanced ionic conductivity of Ag addition in acceptor-doped Bi _0.5 Na _0.5 TiO ₃ ferroelectrics

A promising lead-free ferroelectric material, Bi _0.5 Na _0.5 TiO ₃ (BNT), was recently proposed as an oxide ion conductor. In a survey of BNT perovskite-structured oxides that exhibit ionic conductive grain, it was found to be highly sensitive to stoichiometry and the synthesis processes. The conduction mechanism and defect properties of these BNT therefore could be greatly influenced. Herein, we show composites made by a ferroelectric matrix of acceptor-doped BNT with a slight amount of Ag ₂ O in which the defect and transport properties could be tailored through different sintering atmospheres. The bulk conductivity increased dramatically by 2800 times to 1.36 mS cm ¹ at 502 C.