Co(II)-Co(III) hydrotalcite-like compounds

The synthesis of monometallic hydrotalcite-like compounds (MHLC) type Co(II )-Co(III) materials was achieved by precipitation of a solution of cobalt n itrate(II) followed by microwave irradiation during the hydrothermal treatm ent step. The effects of irradiation time, precipitant agent and atmosphere were studied in order to establish the preparation conditions and the stab ility of these materials. As expected, these materials required careful pre paration conditions, mainly a very slow addition of the precursors. NH,OH h ad to be used as precipitant agent in an air atmosphere. Short microwave ir radiation times during the hydrothermal treatment provided a better crystal lization of MHLC. The low stability of these compounds (similar to 200 degr eesC) was explained by the presence of several Go-complexes between the lay ers of the laminar structure. X-ray diffraction (XRD), Fourier transform in frared spectroscopy (FTIR), differential thermal analysis and thermogravime tric analysis (DTA/TGA), and thermoprogrammed oxidation (TPO) were used as characterization techniques. (C) 2001 Published by Elsevier Science Ltd.