Positive temperature coefficient of electrical resistivity (PTCR) materials with low Curie temperature have been paid increasing attention lately. In this study, PTCR materials with a Curie temperature of approximately -15 °C were investigated by La3+ doping Ba0.55Sr0.45TiO3 ceramics. It could be expected to meet the requirements of thermal management systems for low-temperature control. In addition, a trace amount of Bi0.5Na0.5TiO3 (BNT) was employed to improve the resistivity and the PTCR performance. A significant PTCR effect was achieved with a high resistivity jump of nearly four orders of magnitude, a high temperature coefficient of ~28.76%/°C, and a narrow transition temperature span of 22 °C in the (Ba0.55Sr0.45)0.99875La0.00125Ti1.01O3-0.0025Bi0.5Na0.5TiO3 ceramics. The PTCR enhancement mechanism of BNT is discussed.
Keywords: BST; Bi0.5Na0.5TiO3; PTCR ceramics; low Curie temperature; sol–gel.