Preparation of Ni particles by ultrasonic spray pyrolysis of NiCl2 center dot 6H(2)O precursor containing ammonia

The preparation of nickel particles from nickel ammine complex was studied by ultrasonic spray pyrolysis in the presence and the absence of hydrogen. In the presence of H-2 (about 9 vol.%), nickel particles were formed at 500 degreesC, which is much lower than that reported. Metallic nickel, togethe r with NiO, was obtained as a major phase at 400 degreesC. In the absence o f H-2, metallic Ni was also obtained, but higher temperature (e.g. 900 degr eesC) was needed. It is suggested that the addition of NH3.H2O and NH4HCO3 to NiCl2. 6H(2)O precursor changes the reaction pathway of Ni formation. By careful control, spherical, solid and well-distributed Ni particles of abo ut 0.5 mum were obtained at a residence time of 7-9 s in the aerosol reacto r. (C) 2001 Kluwer Academic Publishers.