Influence of additives on the properties of spherical nickel particles prepared by ultrasonic spray pyrolysis

Ideal spherical nonagglomerated Ni particles (mean diameter 0.62-1.12 mu m) were prepared by ultrasonic spray pyrolysis of NiCl2 aqueous solution in t he presence of 0.1 mass% of Pd, Cu, or Ni in an H-2-N-2 atmosphere at 900 d egrees C. Incomplete reduction of the NiCl2 aqueous solution in the absence of additives was observed under the same conditions. Differential thermal and thermal-gravimetric analyses revealed a decrease in initial reduction t emperature of NiCl2 from 375 to 275 degrees C by the addition of Pd, Cu, or Ni. The morphology of Ni particles was analyzed using scanning tunneling m icroscopy. The surface roughness of Ni particles was found to be controllab le by addition of appropriate additives.