Preparation and characterisation of cobalt–copper hydroxysalts and their oxide products of decomposition

Three cobalt–copper hydroxysalts with chemical formulae Co(CO3)0.5(OH)1.0· 0.11H2O, Co0.67Cu0.33(CO3)0.4(OH)1.2 and Co0.49Cu0.51(CO3)0.43(OH)1.14 have been obtained and characterised by powder X-ray diffraction (XRD), thermal analysis (TG, DTG and DTA), diffuse reflectance spectroscopy (DRS), magnetic susceptibility and X-ray photoelectron spectroscopy (XPS). The above precursors treated at 723 K for 24 h both in N2 and in air give several cobalt and copper oxides which were characterised by magnetic susceptibility, X-ray diffraction, X-ray photoelectron spectroscopy and diffuse reflectance. Depending on the Co : Cu atomic ratios and on the treatments with various gases, the products consist of oxides such as CoO, CuxCo1–xO, CuCoO2 and CuxCo3–xO4 for the samples calcined in N2, and Co3O4, CuxCo3–xO4 and CuO for those calcined in air.