Cobalt ferrite, CoFe 2 O 4 , nanoparticles have been obtained from pre-prepared layered double hydroxide carbonate, LDH-CO 3 , by mechanical milling. X-ray powder diffraction shows the only product of the milling for 5 h of the LDH-CO 3 is cobalt ferrite nanoparticles. Longerterm milling induces particle growth characterized by sharpening of the Bragg peaks and an increase of the blocking temperature, while prolonged milling results in the formation of some cobalt metal. Mo ¨ssbauer spectra and temperature dependence of the magnetization of the 5-h milled sample suggest that it consists of nanoparticles of size less than 10 nm with blocking temperature of 200 K, in good agreement with microscopy showing an average size of 6 nm. The magnetic properties exhibit a strong dependence on the particle size as a result of an unusual cation distribution and of surface effect. The saturation magnetization at 5 K and the squareness of the hysteresis loops increase with the average particle size. The difference between zero-field-cooled and field-cooled hysteresis loops is correlated with the presence of randomness of the moments at the surface.

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High surface area, bulk molybdenum nitride catalysts were synthesized via temperature programmed ammonalysis of ammonium hepta molybdate and citric acid (CA) composite. The sythesized materials were tested for COx free H 2 production via ammonia decomposition for fuel cell application. Cobalt was added in different loadings (1, 3, 5wt %) as a promoter for the bulk molybdenum nitrides. The chemical composition and surface morphology of nitride catalysts were studied by XRD, XPS, SEM-EDAX and TEM techniques. Addition of cobalt increased the formation of γ-Mo 2 N phase and cobalt existed as Co 3 Mo 3 N phase, which was uniformly distributed over Mo 2 N evidenced by TEM and SEM analysis.A drastic increase in Mo 2 N crystal size was observed when the Co loading exceeded 3 wt%, which in turn decreased the catalyst activity for ammonia decomposition reaction. All catalysts are exhibiting high activity than reported nitride catalysts at low temperatures. All catalysts showed stable activity for 30 hours. Activation energy calculated for ammonia decomposition was decreased drastically from 131.2 to 99kJ/mol by the addition of cobalt (1 wt%) in Mo 2 N prepartion.