Up to now, multifunctional varistor-capacitor materials were based on TiO2, even though these materials failed to have practical applications. For the first time, in this research, multifunctional varistor-capacitor properties are observed in the CuO-doped SnO2-CoO-Sb2O3 system. The XRD analysis showed that this system has a single phase microstructure. SEM images indicated that the CuO addition resulted in a better densification and larger grain size. The very low electric breakdown field of the CuO-doped SnO2-CoO-Sb2O3 system (12 V/mm, similar to TiO2), is a consequence of coarse-grained microstructure. This varistor had a suitable surge withstand capability as well. The colossal dielectric constant of about 4.5 * 104 was observed in CuO doped-SnO2 system. This immense constant dielectric can be explained by the internal barrier layer capacitor model. These results attest that the novel multifunctional varistor-capacitor materials based on SnO2 can be used in practical applications.
