Fabrication of high Tc lead free (1 − x)BaTiO3–xBi0.5K0.5TiO3 positive temperature coefficient of resistivity ceramics using reoxidation method

Abstract

(1 – x)BaTiO3−xBi0.5K0.5TiO3 (abbreviated as BT–BKT, where x = 0, 0.1 and 0.2) ceramics were prepared by solid state reaction method. All ceramic samples were sintered in a pure N2 flow atmosphere, subsequently reoxidized at a temperature range of 800–1,100 °C in air for several hours. The influences of BKT content and reoxidation on the positive temperature coefficient of resistivity (PTCR) behavior of ceramic samples were investigated. BT–BKT ceramic samples sintered in N2 possessed relatively low room temperature resistivity (ρRT) and showed weak PTC effect. Through an appropriate reoxidation, the ceramic samples re-obtained PTC effect of almost three orders of magnitude. With the addition of BKT, the Curie temperature (Tc) was enhanced by ~50 °C than the pure BT ceramics.