Low voltage varistor ceramics based on SnO2

Metal Oxide ZnO-Based Varistor Ceramics

Synthesis Mechanism of Low-Voltage Praseodymium Oxide Doped Zinc Oxide Varistor Ceramics Prepared Through Modified Citrate Gel Coating

High demands on low-voltage electronics have increased the need for zinc oxide (ZnO) varistors with fast response, highly non-linear current-voltage characteristics and energy absorption capabilities at low breakdown voltage. However, trade-off between breakdown voltage and grain size poses a critical bottle-neck in the production of low-voltage varistors. The present study highlights the synth...

Homogenized Maxwell’s Equations; a Model for Varistor Ceramics

A model for a semiconducting ceramic material used in devices to protect electrical equipment against overvoltages is presented. The fine structure in the material induces highly oscillating coefficients in the Maxwell equation. Maxwell equations are homogenized to obtain a coupled system. The fine scales in the model yield a local problem coupled with the homogenized Maxwell’s equations. In th...

Crystal phase analysis of SnO2-based varistor ceramic using the Rietveld method

A second addition of lmol% of CoO to a pre calcined SnO2-based ceramic doped with 1.0mol% of CoO, 0.05mol% of Nb2O5 and 0.05mol% of Cr2O3 promotes the appearance of a secondary phase, Co2SnO4, besides the SnO2 cassiterite phase, when the ceramic was sintered at 1350°C/2h. This was observed using X-ray powder diffraction, scanning electron microscopy and energy dispersive X-ray techniques. Rietv...

A Comparative Study of Thermal Conductivity in ZnO- and SnO2-Based Varistor Systems

We performed a comparative study of electrical and thermal properties of ZnOand SnO2-based varistor. The electrical properties of commercial ZnO-based varistor are equivalent to that found in SnO2-based varistor system. In spite of this, the SnO2 showed a thermal conductivity higher than commercial samples of ZnO-based varistor, which allied with its simpler microstructure and lower dopant conc...