Preparation of monodisperse rhombohedron-type nickel oxalate particles from a highly condensed Ni(OH)2 suspension

Monodisperse micron size nickel oxalate particles with rhombohedron morphology were prepared from condensed Ni(OH)2 suspension by a novel gel-sol process proposed by one of the authors. Firstly, condensed nickel hydroxide gel was formed by fast adding 1 mol dm(-3) NaOH solution into 0.2 mol dm(-3) nickel chloride solution, and then oxalic acid solution with a concentration of 0.25 mol dm(-3) was dropped into the gel drop wise through a pump equiped with a pH controller under preset pH value, and in this process, Ni(OH)(2) gel was converted gradually into monodisperse nickel oxalate sol. The formation of the nickel oxalate particles was found to proceed through a dissolution-recrystallization mechanism from the nickel hydroxide gel. The product particles exhibited rhombohedron like shape with micron size long axis and sub-micron size short axis. The effects of such factors, as temperature, surfactants, et at, were evaluated experimentally on the particles sizes and morphologies.