Positive Temperature Coefficient of Resistivity Effect of Semiconducting BaTiO3–(Bi1/2Na1/2)TiO3 Ceramics Prepared by a Wet-Chemistry Route

Without any additional donor dopants, BaTiO 3 –(Bi 1/2 Na 1/2 )TiO 3 (BT–BNT) positive temperature coefficient of resistivity (PTCR) ceramics were successfully prepared by a wet-chemistry route. With 2 mol % BNT addition, the obtained BT–BNT ceramics had semiconductivity and exhibited a PTCR behavior at about 155 °C. The onset temperature of the PTCR effect increased to ∼165 °C for the 4 mol % BNT added samples. Room-temperature resistivity ρ RT increased with the content of BNT added and the ceramics changed from a semiconductor to an insulator, which was consistent with the variation of the microstructure. The temperature of resistivity anomaly in BT–BNT ceramics also increased with increasing BNT content. A small amount of manganese (Mn) dopant was found to improve the PTCR effect in the BT–BNT system. The possible mechanism underlying the PTCR effect in BT–BNT ceramics was proposed.