EFFECT OF COMPOSITION ON THE LATTICE-PARAMETERS AND THERMAL-BEHAVIOR OF NICKEL(II)-COBALT(II) HYDROXIDE NITRATE SOLID-SOLUTIONS

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 NixCo2-x(OH)3NO3 (0 less-than-or equal-to x less-than-or-equal-to 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.