Bondarchuk O. Current saturation in indium oxide based ceramics

The subjects of inquiry are In2O3-SrO ceramics having nonlinear voltage-current characteristic with the sublinear region. The aim of research - to study the mechanism of non-ohmic electrical conduction of new indium oxide based ceramics with sublinear current-voltage characteristic. Methods: experimental (electrical measurements, X-ray photoelectron spectroscopy, X-ray structure analysis, thermogravimetric analysis, electron microscopy), numerical (computer simulation the current-limiting effect in indium oxide based ceramics) and analytical analysis (making comparison the computational modeling result with the experimental data). The thesis is devoted to a synthesis and study of physical properties of indium oxide based ceramics with the functional capability to limit the current. This material has voltage-current characteristic with the current limiting region followed the superlinear region. The current limiting effect was observed, studied and explained. The modified grain-boundary model was suggested. In this model the additional adsorption of oxygen due to a capture of electrons at the grain-boundary states is assumed. Accordingly, the barrier height is increased and current is saturated. The region with positive temperature coefficient of resistance in In2O3-SrO between ~570 and ~670 K was observed. The model for current saturation effect in the fine-grained ZnO ceramic films was proposed.