The effect of TiO 2 on the microstructural and electrical properties of low voltage varistor based on (Sn,Ti)O 2 ceramics

SnO 2 ·CoO·Nb 2 O 5 ceramics doped with TiO 2 have been prepared by a conventional oxide method which focuses its application on low voltage varistors. The dopant was added in 0.5 and 1.0% molar concentrations, and the samples were investigated by X‐ray diffraction, scanning electron microscopy, current vs . voltage, and impedance measurements. The electron microscopy results showed an increase in the mean grain size of ceramics with the addition of TiO 2 , which is related to the effect of the dopant on the matrix. The electrical characterization showed that the addition of TiO 2 in 1 mol% provides a system with a good nonlinear coefficient (8.7) and a breakdown electrical field of 617 V/cm. These results indicate that this composition can be applied as a low voltage varistor. The impedance data showed that the voltage barrier at the grain boundary is a back‐to‐back Schottky‐type, and it was demonstrated that the addition of TiO 2 does not significantly modify the barrier.