Effect of SiO₂ on the Varistor and Dielectric Properties of SnO₂-Zn₂SnO₄ Ceramic Composites

ABSTRACT

SnO₂-Zn₂SnO₄ ceramic composites are prepared by traditional ceramics processing and the effect of SiO₂ on the varistor, dielectric properties has been investigated. With increasing SiO₂ content to 0.2 mol%, the nonlinear coefficient α and the breakdown electrical field E_1.0 gets to the maximum of 7.7 and minimum of 12V.mm^–1, respectively. Meanwhile, the dielectric spectra show that the sample doped with 0.2 mol% SiO₂ has the highest relative permittivity ε_r of ∼7×10³ at 40 Hz, 40°C. The dielectric temperature spectra show that the temperature stability of the dielectric properties can be improved by doping 0.2 mol% SiO₂. The good properties indicate that SiO₂ doped SnO₂-Zn2SnO₄ ceramic composites are viable candidate for capacitor-varistor functional devices to protect electrical micro-machines. Further studies show that the density and grain uniformity of the composites are improved by doping proper content of SiO₂. The compact and uniform microstructure may be responsible for the excellent varistor and dielectric properties.

GRAPHICAL ABSTRACT

Keywords:

• Varistors
• Electroceramics
• Dielectric properties