Preparation and positive temperature coefficient of resistivity behavior of BaTiO3–BaBiO3–Bi0.5Na0.5TiO3 ceramics

Abstract

In this study, as a promising material for lead-free positive temperature coefficient of resistivity ceramics, (1 − x − y)BaTiO3 − xBaBiO3 − y(Bi0.5Na0.5)TiO3 (x = 0.001, 0.002, 0.003; y = 0, 0.002, 0.004, 0.006, 0.01) samples were prepared by the conventional mixed oxide method. All the samples were sintered in air atmosphere for 1 h. X-ray diffraction, scanning electron microscope and resistivity-temperature measurement were used to study the crystal structure, microstructure and resistivity-temperature dependence. The results revealed that proper amount of BaBiO3 doping not only decreased the room temperature resistivity, but also increased the Curie temperature. Its optimal doping content was finally chosen as 0.2 mol%. And with an increase of BNT content, both the Curie temperature and the room temperature resistivity increased. When BaBiO3 = 0.2 mol%, BNT = 0.6 mol%, the Curie temperature was 153 °C and the room temperature resistivity was 1512 Ω cm. When the BNT content increased to 1 mol%, the Curie temperature increased to 157 °C but the room temperature resistivity increased sharply to 4.0 × 105 Ω cm.