Abstract

DIBB, Alessandro et al. Evaluation of rare earth oxides doping SnO₂.(Co_1/4,Mn_3/4)O-based varistor system. Mat. Res. [online]. 2006, vol.9, n.3, pp. 339-343. ISSN 1516-1439.  http://dx.doi.org/10.1590/S1516-14392006000300015.

The present paper aims to verify the inuence of rare earth oxide such as lanthanum (La₂O₃) and neodymium (Nd₂O₃) doping SnO₂ + 0.25%CoO + 0.75%MnO₂ + 0.05%Ta₂O₅ system. The analysis focus on microstructural inuence on electrical properties. Microstructural analysis were made by using Transmission Electron Microscopy (TEM) at different regions of the samples. From such analysis it was found that La₂O₃ and Nd₂O₃ oxides cause heterogeneous segregation and precipitation at grain boundary concerning cobalt and manganese, decreasing the nonohmic electrical properties, as discussed, likely due to the increasing of grain boundary non-active potential barriers.

Keywords : ceramic; varistor; tin dioxide; rare earth oxides.