PTCR characteristics and fabrication of porous, Sb-doped BaTiO3 ceramics

Sb-doped BaTiO3 ceramics containing corn-starch were prepared by sintering at 1350degreesC for 1 h in air. In this study, the effect of corn-starch on positive temperature coefficient of resistivity (PTCR) characteristics and microstructures of Sb-doped BaTiO3 ceramics was investigated. It was found that the porosity and pore size increased and the grain size slightly decreased with increasing corn-starch content. XRD results showed the presence of BaTiO3 peaks only in the Sb-doped BaTiO3 ceramics with and without corn-starch. The PTCR jump of the Sb-doped BaTiO3 ceramics with corn-starch was over 10(6) and 1-2 orders higher than that of samples without corn-starch. The increase in the room-temperature resistivity with increasing corn-starch content was attributed mainly to the increase in the electrical barrier height of grain boundaries and the porosity as well as the partial decrease in the donor concentration of grains and the grain size. It was also noticed that the grain boundary resistivity contributed largely to the total resistivity of the Sb-doped BaTiO3-corn-starch ceramics.