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

(1 - x)BaTiO3-xBi(0.5)K(0.5)TiO(3) (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 N-2 flow atmosphere, subsequently reoxidized at a temperature range of 800-1,100 A degrees 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 N-2 possessed relatively low room temperature resistivity (rho(RT)) 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 similar to 50 A degrees C than the pure BT ceramics.