Synthesis of LaMO sub(3) (M = Fe, Co, Ni) using nitrate or nitrite molten salts

Perovskite compound LaMO sub(3) (M = Fe, Co, Ni) nanocrystals were successfully synthesized in molten nitrates or nitrites from a mixture of lanthanum nitrate and an M-containing nitrate for 2 h. The effect of the various process parameters on the phase purity, crystallite size, specific surface area and morphology of the synthesized nanocrystals were systematically studied by XRD, scanning electron microscopy (SEM), simultaneous TG/DSC and BET measurements. The results showed that salt medium, annealing temperatures (mainly 450-850 degree C), oxidising properties and basicity of the melt played an important role in the synthesis of LaMO sub(3). The addition of Na sub(2)O sub(2) facilitated the reaction between La sub(2)O sub(3) and NiO or Co sub(3)O sub(4), leading to the formation of LaNiO sub(3) and LaCoO sub(3) at a much lower temperature of 450 degree C. Pure hexagonal LaNiO sub(3) nanocrystals were obtained in molten NaNO sub(3)-KNO sub(3) eutectic with Na sub(2)O sub(2) at 550-750 degree C.