Potential Barrier Behavior of BaTiO sub(3)-(Bi sub(0.5)Na sub(0.5))TiO sub(3) Positive Temperature Coefficient of Resistivity Ceramic

High-Curie-temperature (T sub(c)) lead-free Y-doped 90mol%BaTiO sub(3)-10mol%(Bi sub(0.5)Na sub(0.5))TiO sub(3) ceramic with positive temperature coefficient of resistivity (PTCR) is prepared by the conventional solid state reaction in nitrogen atmosphere. The PTCR ceramic exhibits a room-temperature resistivity ([rho]25) of ~500 ohm.cm and a high PTCR effect (maximum resistivity ([rho] sub(max))/minimum resistivity ([rho] sub(min))) of ~4.5 orders of magnitude. A capacitance-voltage approach is first employed to calculate the potential barrier ([Phi]) of the grain boundary of PTCR ceramic above T sub(c). It is found that the potential barrier changes from 0.17 to 0.77eV as the temperature increases from 180 to 220[degrees]C, which is very close to the predictions of the Heywang-Jonker model, suggesting that the capacitance-voltage method is valid to estimate the potential barrier of PTCR thermistor ceramics.