Preparation of fine Ni particles by the spray-pyrolysis technique and their film forming properties in the thick film method

Fine Ni particles were directly prepared from Ni(NO₃)₂ and NiCl₂ aqueous solutions by the spray-pyrolysis technique under an H₂-N₂ atmosphere. Hollow Ni particles with rough surfaces were obtained at a low reaction temperature (700–900 °C). With increasing reaction temperatures from 900 °C to 1500 °C, the particles varied gradually to solid ones with a smooth surface, and the particles obtained at 1600 °C were perfectly spherical ones whose average size was ∼0.6 μm. From the point of view that aggregation free powders are considered to be good for thick film applications, Ni(NO₃)₂ was preferred to NiCl₂ as a starting material. The perfectly spherical particles derived from Ni(NO₃)₂ gave a Ni film about 3 μm in thickness having sheet resistance of 37.7 mΩ · square⁻¹.