Preparation of Ni–MgO core-shell nano powders

Nickel nanopowders coated by magnesium oxide used for inner electrode of multilayer ceramic capacitor (MLCC) were prepared by coating thermal decomposition sintering method. The effects of reactant concentration and dispersant content on the particle size and homogeneity of the nano-coated nickel salt precursors were investigated, and the influences of reduction sintering temperature on the sphericity and dispersion of the coated nano-nickel powders were discussed. The nickel nanopowders coated by MgO were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and thermomechanical analyzer (TMA). The results show that the nano-nickel salt particles can be obtained when the reactant concentration reaches enough to cause the reaction explosion nucleation. The well-dispersed nano-nickel salt precursor particles can be obtained by adding the proper dosage of dispersant. The nickel nanopowders coated by MgO with good sphericity and dispersion can be obtained at the reduced sintering temperature of 700 ℃. The core-shell structure of the nickel nanopowders coated by MgO is formed, which show the good shrinkage delay effect.