Preparation and characterisation of BaTiO 3 based PTC ceramics with high performance

The nanocrystalline BaTiO₃ based PTC powders had been prepared by a simple sol–gel method starting from comparatively cheap raw materials. The powders and ceramics were characterised by thermogravimetry–differential scanning calorimetry, X-ray diffraction and scanning electron microscopy, while electronic properties of the ceramics were also studied. The good material electronic properties were obtained, including a Curie temperature (T_C) of 100°C, a resistivity at room temperature (ρ_25°C) of 18 Ω cm, a high resistivity step ratio (ρ_max/ρ_min) of 1·2×10⁶, a temperature coefficient of resistivity (α₃₀) of 17% °C⁻¹ and a withstand voltage intensity (V_b) of 196 V mm⁻¹.