Morphology, microstructure, and surface area of La-added MgFe<sub>2</sub>O<sub>4</sub> powder

La-added and pure MgFe2O4 powders were prepared from a malic acid complex, and the effect of La-adding on the microstructure and specific surface area of MgFe2O4 powder were examined. There were no traces of impurity phases for pure MgFe2O4 powder in the X-ray diffraction measurement after calcination in the range of 600 to 800°C. When La atoms were added to MgFe2O4, the crystallite growth of MgFe2O4 was suppressed remarkably, resulting in a higher specific surface area in comparison with the pure material, and the lattice volume increased. X-ray photoelectron spectroscopy measurements showed that the binding energies of Mg 2s, Fe 2p, O 1s, and La 3d signals were in good agreement with the Mg2+, Fe3+, O2−, and La3+ valence states, respectively. Scanning electron microscopy observations revealed that MgFe2O4 powder shows an aggregation of granular particles and that the individual particles are tightly interconnected with each other, whereas smaller particles compared with pure MgFe2O4 were observed for the La-added powder. It was found from the N2 adsorption measurement, moreover, that the amount of mesopore increases with La addition.

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