The Synthesis of Nano-Sized Metal Dispersed MgO Composites and Its Magnetic Properties

Nanocrystalline Ni or Co dispersed MgO nanocomposites were fabricated by the reduction and sintering of composite powders. The powder mixtures were prepared by solution chemical processes to obtain a desirable microstructure for ceramic /metal nanocomposites. Nikel or cobalt nitrate, as a source of metal dispersion, was dissolved into alcohol and mixed with magnesia powder. After calcined in air, the metal oxide in the mixed powders were reduced by hydrogen. Through microstructure observations, the nanocomposite powders containing nanometer sized MgO and metallic particles were obtained by adjusting the calcination and reduction conditions. Densified nanocomposites were obtained successively by Pulse Electric Current Sintering (PECS) process. The dispersed metal particle size depended on treatment temperature and time in calcination and reduction processes. The phase analyses of the synthesized powders as a function of temperature were tracked using a dynamic high temperature X-ray diffraction (HTXRD) system. Phase and crystallite size analyses were done using X-ray diffraction and TEM. Through these processes, the MgO/metal nanocomposites were successfully fabricated, and ferromagnetic responses with enhanced coercive force were also observed for these composites.