PTCR effect in BaBiO3-doped BaTiO3 ceramics

BaBiO3 shows, at room temperature, a distorted perovskite lattice with monoclinic unit cell (I2/m) characterized by two different B sites, occupied respectively by Bi3+ and Bi5+. The influences of BaBiO3 content on the electrical property and the microstructure of BaTiO3-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 BaBiO3 content the grain size decreases rapidly. All the prepared BaBiO3 doping BaTiO3-based thermistors show typical PTC effect. As the amount of BaBiO3 added in BaTiO3-based ceramics increases, resistivity appears to exhibit a minimum value. At high BaBiO3 content (≥ 0.3), the resistivity increased again with increasing BaBiO3 content. At a given content of BaBiO3, the influence of sintering temperature on the electrical properties of samples has been investigated. A maximum of ρmax/ρmin ratio was obtained at the sintering temperature equal to 1290 °C at a given content of BaBiO3.