The preparation and electrical properties of SrTiO3-based capacitor-varistor double-function ceramics

SrTiO3 powders were prepared using a sol-gel process. The electrical properties and the microstructure of doped SrTiO3-based capacitor-varistor double functions ceramics prepared by the sol-gel process were compared with those of ceramics prepared via the solid-state reaction method using X-ray diffraction, scanning electron microscopy, and measurements of dielectric constants and current-voltage characteristics. The sol-gel based materials exhibited enhanced capacitor-varistor properties compared to those prepared by a conventional solid-state method. These enhanced properties are attributed to the smaller, more uniform grain structure obtained in the sol-gel-derived material, which promotes the formation of an effective core-shell structure in which an acceptor-doped layer encapsulate the donor-doped SrTiO3 grains. The effect of such microstructures on electrical properties is discussed.