A novel method of preparing Ba0.96Ca0.04Ti1.02O3 ceramics with low room temperature resistivity

Using an ordinary ceramic processing technique, a new method of preparing Ba0.96Ca0.04Ti1.02O3 positive temperature coefficient resistors (PTCR) ceramics with low room temperature (r.t.) resistivity is introduced. The ceramics are prepared by mixing powder A, containing low concentration of donor dopants (0.12 mol.% Sb2O3), with powder B, containing high concentration of donor dopants (0.24 mol.% Sb2O3). As the weight ratio of A to B, A/B, is 10:1, the samples of PTCR ceramics with r.t. resistivity (∼5.0 Ω cm) are obtained. The ceramics exhibit PTC properties with ρmax/ρ25 as great as 104.1, and breakdown voltage as high as 120 V mm−1, which are much higher than those of the conventional BaTiO3 ceramics with the same r.t. resistivity prepared from one kind of PTCR powder. With the aid of grain boundary theory, the influence of microstructure on electrical properties is discussed.