PTCR effect in BaBiO3-doped BaTiO3 ceramics

BaBiO 3 shows, at room temperature, a distorted perovskite lattice with monoclinic unit cell ( I2/m ) characterized by two different B sites, occupied respectively by Bi 3+ and Bi 5+ . The influences of BaBiO 3 content on the electrical property and the microstructure of BaTiO 3 -based materials have been studied. At a low dopant concentration the grain size is not influenced significantly by the donor concentration. With an increase in BaBiO 3 content the grain size decreases rapidly. All the prepared BaBiO 3 doping BaTiO 3 -based thermistors show typical PTC effect. As the amount of BaBiO 3 added in BaTiO 3 -based ceramics increases, resistivity appears to exhibit a minimum value. At high BaBiO 3 content (≥ 0.3), the resistivity increased again with increasing BaBiO 3 content. At a given content of BaBiO 3 , the influence of sintering temperature on the electrical properties of samples has been investigated. A maximum of ρ max / ρ min ratio was obtained at the sintering temperature equal to 1290 °C at a given content of BaBiO 3 .