PREPARATION OF MONODISPERSE RHOMBOHEDRON-TYPE NICKEL OXALATE PARTICLES FROM A HIGHLY CONDENSED Ni(OH)_2 SUSPENSION

摘要

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 al, were evaluated experimentally on the particles sizes and morphologies.