Characteristics of Porous Sb-Doped Barium Titanate Ceramics Fabricated by Adding Graphite

Abstract

Porous Sb-doped barium titanate (Sb-BaTiO3) ceramics were fabricated by adding various amounts of graphite powders. The density, structure, microstructure, porosity and electrical resistivity of the porous Sb-BaTiO3 ceramics produced without and with graphite were investigated. All the sintered ceramics showed a tetragonal perovskite structure, irrespective of the amount of graphite added. The porosity of the ceramics increased and the grain size decreased with increasing graphite addition which mainly due to the exothermic reactions of the graphite and oxygen molecules in the ceramics. The prepared porous Sb-BaTiO3 ceramics exhibit PTCR behavior where the PTCR jump of the ceramics with graphite was about 103 which is higher than that of the ceramics without graphite. The increasing in the PTCR jump with increasing graphite addition was attributed mainly due to the increase in the electrical barrier height of grain boundaries and the porosity. It was found that the graphite is an effective pore forming agent for fabricating porous BaTiO3-based ceramics.