Solution combustion synthesis of CeO2–CeAlO3 nano-composites by mixture-of-fuels approach

Nano-composites of CeO2–CeAlO3 are synthesised by solution combustion method employing (a) urea and (b) a mixture of urea and glycine as fuels with corresponding metal nitrates. The as-prepared powders are all nano-sized (5–30 nm) and the same is confirmed by broadening of the X-ray diffraction peaks and transmission electron microscopy. A starting composition of Ce:Al in the atomic ratio 4:6 gives rise to different phases depending on the fuel being used for combustion. When urea alone is used as fuel, nano-crystalline CeO2 phase is formed with Al2O3 being in the amorphous state. When the mixture of fuels is used, a mixture of nano-sized CeO2 and CeAlO3 phases is obtained. However, upon sintering at 1400 °° C in air, the stable phases CeO2 and α-Al2O3 are formed in both the cases. Combustion synthesis using mixture-of-fuels is proposed to be a route to stabilise low oxidation compounds such as CeAlO3.