Microscopic analysis and electrical properties of TiO_2 varistor ceramics

The effects of sintering temperature on microstructure, micro-composition, barrier structure and electrical properties of TiO2 varistor ceramics were investigated. Microstructures and grain’s chemistry compositions of samples were tested by SEM and EDS methods. Based on the thermoelectronic emission theory, barrier structure of samples was calculated by analyzing electrical properties of samples. The sample sintered at 1 350 ℃ exhibits a compact and homogeneous microstructure. The grains size of the TiO2 sample is about 15 μm, solid solubility of donor doping Nb5+ solute in TiO2 grains of 1.49 %, B of 0.28 eV, xD of 48 nm, V1mA of 5.25 V/mm, α of 4.2 and er of 1.1×104.