Surface studies of nano-dimensional particle size iron-manganese spinel mixed oxides

Monophase binary iron-manganese spinel oxides of high dispersity are prepar ed by thermal decomposition of carbonate precursors in the limits 0.33 less than or equal to Fe/Mn less than or equal to 2, at temperatures 570-770 K. Interparticle meso- and macropores contribute to the surface morphology of the spinel oxides, composed from spherical-shaped particles with diameters in the range 7-12 nm. The cation distribution of manganese ferrite corresp onds to Mn0.85Fe0.15[Mn0.14Fe1.86]O4+delta. Surface analysis by ESCA reveal s high concentration of nonstoichiometric oxygen and presence of Mn(LII) an d Mn(IV) is indicated in the X-ray photoelectron spectra. Reduction with hy drogen proceeds in two steps and is shifted to higher temperatures with inc reasing the iron content.