Investigation on low room-temperature resistivity Cr/(Ba0.85Pb0.15)TiO3 positive temperature coefficient composites

Low room-temperature resistivity positive temperature coefficient (PTC) Cr/(Ba0.85Pb0.15)TiO3 composites were produced via a reducing sintering and a subsequent oxidation treatment. The effects of metallic content and processing conditions on materials resistivity–temperature properties were discussed. Using these special processes, the prepared composite with 20 wt% Cr possessed low room-temperature resistivity (2.96 Ω cm at 25 °C) and exhibited PTC effect (resistivity jump of 10), which is considered as a promising candidate for over-current protector when working at low voltage. The grain-boundary potential barrier of the prepared PTC composite was evaluated based on the Heywang model and the experimental data. The potential barrier was from 0.00 to 0.11 V in the temperature range of 180–270 °C, which is believed to be the first reported intrinsic parameter for PTC composite, determined from the experiment.