Fabrication and positive temperature coefficient of resistivity properties of semiconducting ceramics based on the BaTiO 3–(Bi 1/2K 1/2)TiO 3 system

Abstract

BaTiO 3–(Bi 1/2K 1/2)TiO 3 (BT–BKT) ceramics have a low ρ RT of 10 1–10 2 Ω cm like that of semiconducting materials prepared by sintering in a N 2 flow with low O 2 concentration. By annealing in air, the BT–BKT ceramics show an abrupt increase in their resistivity near the T c, 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, ρ max/ ρ RT, of the highest resistivity ( ρ max) and the resistivity at room temperature ( ρ RT) of the ceramics increased on adding a small amount of Mn and a sintering aid.