Cobalt hexafluoroacetylacetonate polyether adducts for thin films of cobalt oxides

The novel [Co(C5F6HO2)2 · 2H2O · CH3(OCH2CH2)2OCH3] and [Co(C5F6HO2)2 · 2H2O · CH3(OCH2CH2)3OCH3] low-melting adducts have been synthesized and characterized by elemental analysis, IR spectroscopy, mass spectra and TG–DTG thermal measurements. The former adduct is liquid at room temperature, whilst very mild heating of the latter results in a thermal stable liquid compound. Both adducts can easily be evaporated. Deposition experiments, in a low-pressure horizontal hot-wall reactor, on optical transparent SiO2 substrates, using these precursors, result in CoO or Co3O4 films, depending on the deposition conditions. XRD measurements provide evidence that CoO and Co3O4 consist of cubic, highly oriented, (2 0 0) and (3 1 1) crystals, respectively. The mean crystallite sizes were evaluated from the XRD line broadening. Both optical spectra and resistivity measurements of Co3O4 films show that they are semi-conducting and their band-gap was determined from the optical induced transitions. The film cross section and the surface atomic composition were investigated by SEM and XPS analyses, respectively.

Graphical abstractThe diglyme adduct shows a 5.5% mass loss consistent with a dehydration process. The remaining anhydrous, liquid adduct evaporates intact and quantitatively afterward.Figure optionsDownload full-size imageDownload as PowerPoint slide