On the existence of copper cobaltite

The preparation and structure of the double oxide CuCo₂O₄, the existence of which has been disputed, are discussed. This compound, a spinel of lattice parameter a = 8.084 Å, can be obtained in the simple way proposed by Holgersson & Karlsson in 1929. A comparison is made with the spinel ZnCo₂O₄, whose cell parameter a is 8.088 Å. X-ray powder diffraction data for both compounds are included.