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

Abstract

Three cobalt–copper hydroxysalts with chemical formulae Co(CO₃)_0.5(OH)_1.0· 0.11H₂O, Co_0.67Cu_0.33(CO₃)_0.4(OH)_1.2 and Co_0.49Cu_0.51(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, Cu_xCo_1–xO, CuCoO₂ and Cu_xCo_3–xO₄ for the samples calcined in N₂, and Co₃O₄, Cu_xCo_3–xO₄ and CuO for those calcined in air.