Fully stabilized zirconium dioxide is widely used. One of the basic requirements to this material is the thermal stability of the structure. The most effective stabilizer for zirconium oxide is yttrium oxide. However, the structure of Y-ZrO2 degraded at low temperature. Partial substitution of Fe3+ for Y(3+)supercript stop decreases both the crystallization and sintering temperature of zirconia ceramic. The aim of present work is the investigation of structural peculiarities of zirconium oxide stabilized by combined dopant depending on chemical composition, synthesis conditions and heat treatment. The polymorphic composition of a ZrO2-based materials has been determined in series of samples that correspond to the formula [1-(x+y)](ZrO2Y2O3Fe2O3)-Y-.x-Fe-. in the temperature range 620-1570 K. It has been found that at the same molar ratio ZrO2 : doping oxides, the degree of ZrO2 stabilization increases, and the low-temperature degradation process is retarded by the partial substitution of Fe3+ for Y3+. Nonequivalent sites of Fe3+ ions have been identified: two with octahedral coordination for CPH and three with octa-, penta- and tetrahedral coordination for SPH. The possibility of cluster distribution of Fe3+ ions and the dependence of the number of vacancies on synthesis conditions have been shown. (c) 2005 Springer Science + Business Media, Inc.