Zirconia-based metastable solid solutions through self-propagating high-temperature synthesis: Synthesis, characterization, and mechanistic investigations

Cubic Zr1-xMexOy (Me = Fe, Co, Ni, Cu) metastable solid solutions with meta l content significantly higher than equilibrium levels have been synthesize d by the self-propagating high-temperature synthesis method based on a ther mite reaction between metallic zirconium and the transition-metal oxides Co O, Fe2O3, CuO, and NiO. Through in situ XRD analysis, it was determined tha t when heated to 1100 degrees C, the cubic solid solution transformed to th e tetragonal phase with the concomitant formation of iron oxide. When coole d to lower temperatures, the tetragonal phase transformed to the monoclinic phase at or below 500 degrees C, Results of auxiliary experiments strongly suggest that the Formation of the solid solution takes plate behind the co mbustion front by a reaction between zirconia and the metal.