Neutron diffraction study of the cationic distribution in Cu xCo 3− xO 4 (0< x⩽1.0) spinels prepared by thermal decomposition of layered hydroxide nitrate precursors

Abstract

A neutron powder diffraction refinement of the structure parameters of six samples of copper cobalt oxide spinels Cu x Co 3− x O 4 (0 < x ⩽ 1.0), prepared by thermal decomposition of layered hydroxide nitrate precursors has been carried out. It was found that the Cu 2+ ions are statistically distributed over the tetrahedral ( A) and the octahedral ( B) lattice sites. This particular cationic distribution is responsible for the observed cubic lattice symmetry and the dependences of the unit cell parameters, the oxygen parameter and the tetrahedral and octahedral bond lengths on the copper content, x, in the formula unit. The results can be regarded as the first direct confirmation of the suggestion that the cationic distribution in the spinels is predetermined by the structure of the precursors and the mechanism of their thermal decomposition.