Influência de dopantes doadores na degradação do varistor à base de SnO2 e o efeito do oxigênio pós-degradação

Abstract

A degradação elétrica de varistores à base de SnO2 foi estudada e verificou-se que na temperatura de 220 ºC ocorreu a degradação do material. Suas características foram recuperadas quando tratadas em atmosfera de O2, o que mostra que esta atmosfera é fundamental para a característica do varistor.

Electrical Properties of a TiO₂-SrO Varistor System

“…The Eb value also decreases with density and increases with the sintering temperature, bus as the SrO concentrations increa, the Eb value decreases, probably because of the formation of electronic barriers in the grain boundary of the TiO 2 network. These results are in agreement with what is expected from the addition of dopants, as these may influence the formation of the energy diagram of the grain boundaries by changing the form of potential barriers [22,18,23].…”

Improvement in varistor properties of CaCu3Ti4O12 ceramics by chromium addition

“…Thermal avalanche is a phenomenon in which a reduction in the nonlinearity coefficient occurs as the temperature increases [59]. The increase in temperature favours the mobility of the species located in the bulk that recombined with the species located in the grain boundary, facilitating the reduction in potential barrier height, allowing all current to cross the thickness of the sample, leading to material degradation [59].…”