Effect of composition on the lattice parameters and thermal behaviour of nickel(II)–cobalt(II) hydroxide nitrate solid solutions

Abstract

A series of coprecipitated nickel(II)–cobalt(II) hydroxide nitrate samples with different cationic compositions has been studied by means of X-ray diffraction, infrared spectroscopy and thermal analysis. A continuous series of solid solutions Ni_xCo_2–x(OH)₃NO₃(0⩽x⩽2) is formed between the end members Ni₂(OH)₃NO₃ and Co₂(OH)₃NO₃. The observed changes in the IR spectra have been interpreted in terms of increased polarization of the NO₃ ^– group and increased strength of the hydrogen bonds when Ni²⁺ is gradually substituted for Co²⁺. The thermal stability of the solid solutions as well as the phase composition of the solid products of thermal decomposition depend upon the initial Ni : Co ratio in the samples.