Autoclave Synthesis of Finely Divided Nickel Powders

The reduction of divalent nickel with hydrazine hydrate from alkaline ammonia solutions at elevated temperatures was studied. A procedure to synthesize finely divided nickel powders was proposed. The morphology of the objects obtained under various synthesis conditions was investigated by scanning electron microscopy; it was shown that both needle-like and spherical particles can form. The specific surface area of the synthesized metallic nickel powders was determined by low-temperature nitrogen adsorption to be within the range 5-20 m(2)/g, depending on the synthesis conditions (the concentration of the initial salt in the solution, the pH, and the temperature). X-ray powder diffraction analysis showed that all the powders are mixtures of two phases: nickel (to 99%) and nickel hydroxide. X-ray photoelectron spectroscopy demonstrated that a particle of the powders consists of a nickel(0) core coated with several atomic layers of nickel hydroxide.

Automated summary

The research studied the reduction of divalent nickel with hydrazine hydrate from alkaline ammonia solutions at elevated temperatures and proposed a method to synthesize finely divided nickel powders. It was found that needle-like and spherical particles can form under different synthesis conditions, with the specific surface area of the metallic nickel powders ranging from 5-20 m(2)/g depending on the synthesis conditions. X-ray analysis showed that the powders are mixtures of nickel and nickel hydroxide, with X-ray photoelectron spectroscopy revealing that the particles consist of a nickel(0) core coated with nickel hydroxide layers.