INFLUENCE OF ADDITIVES ON THE ELECTRICAL-PROPERTIES OF DENSE SNO2-BASED CERAMICS

Highly densified 0.99 SnO2-0.01 CuO-based ceramics with antimony, tant alum, or niobium oxides as additives have been prepared. Samples have been characterized by dc conductivity and complex impedance spectrosco py as a function of temperature and by current density as a function o f electric field. Microstructures have been analyzed by scanning elect ron microscopy, electron microprobe, and Auger spectroscopy. The elect rical properties of Ta- and Nb-doped ceramics are grain boundary contr olled at least at low temperature. Sb-doped materials show a different electrical behavior due to the presence of a segregation layer of ant imony which inhibits grain boundary effects.