Guidance Evolution Mechanism of Nickel Oxalate Micro- structure for Formation of Polycrystalline Nickel Nano-fibers

Nickel oxalate nano-fibers were controllably synthesized via a restricted self-assembly growth process in a liquid phase precipitation system. Nickel nano-fibers were prepared by decomposing nickel oxalate under the guidance of fiber micro-structure in Ar gas atmosphere. The characteristics of the samples were measured by X-ray powder diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM). Result show that the existence of ammonia changes the growth behavior of nickel oxalate from free self-assembly mode to a restricted one. The nickel oxalate crystal nano-fibers with monoclinic geometry are 100∼200 nm in diameter, and 1∼5 μm in length. The nickel nano-fibers with face-centered cubic geometry are also 100∼200 nm in diameter, and 1∼5 μm in length, and the surface is very rough. Nickel nano-fibers are formed via a process of nucleation, grain growth and aggregation under the guidance of long and narrow space provided by nickel oxalate nano-fibers.