Possible Suppression of Partial Electronic Conductivity of CeO2-based Electrolytes by Electron Traps

A critical drawback of ceria-based electrolytes is that they are much more prone to reduction, thus limiting the lower bound of their electrolytic domain to much higher oxygen activity than the classic electrolyte YSZ. We examined the possibility to suppress the partial electronic conductivity, thus to expand the electrolytic domain width, of acceptor(A)-doped Ce(1-x)A(x)O(2-x/2) by trapping reduction-induced electrons by variable valence impurities with 3d (Ti, Mn, Fe, Co, Cu) and 4f electrons (Eu, Yb, Sm, Tb). It has been found that a few of 4f elements are indeed effective to extend the domain width to lower oxygen activity by as much as two orders of magnitude. We report the results of suppressing the partial electronic conductivity of Ce(1-x)A(x)O(2-x/2).