Compositional and processing effects on electrical properties of (Ba0.85Pb0.15)TiO3-based positive temperature coefficient resistors

In the present work, (Ba0.85Pb0.15)TiO3-based positive temperature coefficient resistors (PTCRs) with low room-temperature resistivities were produced, and the effects of composition and processing conditions on materials electrical properties were investigated. For (Ba,Pb)TiO3-based ceramics, it was noted that an addition of double donors Sb2O3+Nb2O5 led to a lower room-temperature resistivity than that of single donor Nb2O5. The resistivity followed to reduce when properly increasing the donor concentration and decreasing the acceptor (MnO2) concentration. The correlation of sintering temperature with ceramic parameters, namely, density, grain size, room-temperature resistivity, resistivity jump, and room-temperature breakdown strength, was discussed. Metal Cr was added to ceramic matrix to further reduce the resistivity. A reducing sintering and a subsequent oxidation treatment processes were employed, and the influences of metallic content and processing conditions on composite density, room-temperature resistivity, and room-temperature breakdown strength were analyzed. Low room-temperature resistivity PTCRs were produced by controlling both Cr content and the processes.