Production and characterization of the oxide enriched materials for ceramic varistors II. Synthesis, chemical and physico-structural analysis, conductive grains doping influence upon the current-voltage characteristics

The paper presents two new products of synthesis based on enriched ZnO, obtained by sequential coprecipitation and respectively, the procedures (methods) for obtaining the active tablets from. the structure of the ceramic varistors. These contain two heterojunctional-structures; the conductive grains based on ZnO enriched with Mn (II, III) oxides and the intergranulator dielectric film made of Sb(III) and Bi(III) oxides' eutectoid. The products are characterised by the chemical analysis, thermogravimetry, IR spectroscopy and X-ray diffraction, emphasising the composition and the distribution of the two phases (conductive grains and the intergranulator dielectric film). There is also presented the influence of the enrichment with Mn (II, III) oxides of the conductive grains based on ZnO on the current-voltage characteristics.