Complex impedance analyses of PTCR ceramics based on barium-lithium-bismuth titanate

The formation of (1-x)BaTiO₃-xLi_0.5Bi_0.5TiO₃ (0 ≤ x ≤ 0.6) solid solutions with positive temperature coefficient of resistance (PTCR) effect was studied. Powders were prepared by solid-phase reaction technique. Ceramics were sintered under reducing atmosphere N₂/H₂ in the temperature range 1200-1450°C with subsequent oxidation in air. It was shown that minimum value of resistivity rises with increase in x value. Complex impedance analysis shown that ceramic grains of (1-x)BaTiO₃-xLi_0.5Bi_0.5TiO₃ materials consist of three areas with different electrical properties. Boundaries and outer layers of grains make the main contribution to the PTCR effect in lithium-containing solid solutions. The potential barrier decreases with increasing x.