BaTiO 3 – ( Bi 1 ∕ 2 Na 1 ∕ 2 ) TiO 3 solid-solution semiconducting ceramics with Tc>130°C

Abstract

As a candidate of a lead-free positive temperature coefficient of resistivity (PTCR) material, barium titanate (BaTiO3)-based solid-solution ceramics, Ba1−x(Bi1∕2Na1∕2)xTiO3 with x=0.05 (BBNT5), have been synthesized by an ordinary sintering technique. Temperature dependences of the dielectric and ferroelectric properties show ferroelectric and paraelectric phase transition of the ceramics with the Curie temperature of Tc=170°C, which is higher than that of BaTiO3 (130°C). The La-doped BBNT5 ceramics display low ρ values of 102–103Ωcm at room temperature and their abrupt changes of 102–104 at about 220 °C. The reduced BBNT5 ceramics show small PTCR characteristics compared to the La-doped ones.