Preparation of ceria–zirconia (Ce0.75Zr0.25O2) powders by microwave–hydrothermal (MH) route

Binary mixed metal oxides, having composition Ce0.75Zr0.25O2 were prepared by microwave–hydrothermal (MH) reaction (200 °C, 200 psi, 30 min) using ZrO(NO3)2·xH2O, Ce(NO3)3·6H2O as starting precursors and KOH as mineralizer. 0.025, 0.075 and 1.2 M solutions of ZrO(NO3)2·xH2O, Ce(NO3)3·6H2O and KOH, respectively, are used for MH synthesis. Solution (7.5 ml) of each of ZrO(NO3)2·xH2O (0.025 M) and Ce(NO3)3·6H2O (0.075 M) are mixed with 25 ml of KOH and treated in specially designed vessels using microwave accelerated reaction system to obtain ceria–zirconia solid solution. Various physico-chemical techniques such as XRD, Raman, SEM, EDAX, TEM, BET, etc. are used to characterize the resultant powders. The results showed that the as-prepared powder particles consisted of solid solution of ceria–zirconia having cubic fluorite structure with surface area equal to 125 m2 g−1. SEM/TEM photographs for the same showed varied distribution of agglomerates with primary particle size≅7 nm. The cubic phase is obtained at a temperature (pressure) and time as low as 180 °C (127 psi) and 5 min.