An improved chemical reduction route for fine nickel powders

Abstract

We report an improved chemical reduction route toward fine nickel powders by using nickel hydrazine complexes [Ni(N2H4) 3SO4 and Ni(N2H4)nCl 2 (n = 2 and 3)] as the starting materials, rather than Ni(OH) 2, which is used in the conventional procedure. The reductions of the hydrazine complexes had reaction rates that were three to ten-fold higher than those of the conventional method. As a result, the products consist of homogeneous, phase-pure, spherical, fine nickel particles that have smooth surfaces; they were formed without the need for additives or extreme reaction conditions. The reaction rates could be related to the solubilities of the precursors, which increase in the order Ni(N2H4) 2Cl2 > Ni(N2H4) 3Cl2 > Ni(N2H4) 3SO4; we propose a reaction mechanism based on this observation.