Fabrication and positive temperature coefficient of resistivity properties of semiconducting ceramics based on the BaTiO3–(Bi1/2K1/2)TiO3 system

BaTiO3–(Bi1/2K1/2)TiO3 (BT–BKT) ceramics have a low ρRT of 101–102 Ω cm like that of semiconducting materials prepared by sintering in a N2 flow with low O2 concentration. By annealing in air, the BT–BKT ceramics show an abrupt increase in their resistivity near the Tc, namely, a positive temperature coefficient of resistivity (PTC) characteristic. With 5 mol% and 10 mol% BKT added to BT, the ceramics display the PTC characteristic at 155 °C and 165 °C, respectively. Furthermore, the ratio, ρmax/ρRT, of the highest resistivity (ρmax) and the resistivity at room temperature (ρRT) of the ceramics increased on adding a small amount of Mn and a sintering aid.