LOW-TEMPERATURE STABILIZATION OF ZIRCONIA BY MN THROUGH CO-PRECIPITATED HYDROXIDE GEL ROUTE

Stabilization of zirconia into cubic phase is achieved by partly substituting Zr4+ with Mn4+ ions (5-30 mole %) via hydroxide gel formation and subsequent calcination at 773 K and is supported by XRD and IR data. A linear correlation between the lattice parameter and the Mn content confirms the incorporation of Mn into ZrO2. The XPS and TPR results provide some evidence for the presence of Mn4+ ions in these samples which have a surface area of about 100 m2 g-1 and are stable in the cubic phase up to 973 K. On reduction above 973 K, the cubic phase is stabilized probably by Mn2+ ions.