ZnO thin films deposited by chemical bath deposition (CBD) have been studied using x-ray diffraction, scanning electron microscopy, electron microprobe analysis and electrical measurements. The optimum CBD conditions for achieving structured, but adherent, ZnO films are as follows. Zinc acetate (0.0188 mol l−1) and ethylenediamine (0.03 mol l−1) are mixed. The pH of the bath is raised by addition of a base (0.5 mol l−1, NaOH). The solution is maintained at a temperature between 60 °C and 65 ° C, while the bath is continuously stirred. We proceeded to anneal in room air for 30 min at 300 °C and under vacuum for 2 h at 300 °C. All the films obtained are nearly stoichiometric ZnO films crystallized in the usual hexagonal structure. As expected the films are rough and porous. The main difference between the two ZnO film families is their conductivity. The conductivity of the films annealed under vacuum is five orders of magnitude higher than that of those annealed in room air.
Chemical and structural characterizations of natural phosphates of Hahotoe (Togo) have been performed. From chemical analysis and FTIR study, it can be concluded that the material is carbonated fluoroapatite with poor substitution of calcium by cadmium and manganese. From these results, the molecular formula proposed is: Ca 9.925 Cd 0.004 Mn 0.013 [(PO 4) 5.886 (CO 3) 0.113 ]F 2. Powder X-ray diffraction fitting results confirm that compound belongs to the apatite family crystallising in the hexagonal system, space group P6 3 /m. The cell parameters are: a = 9.3547(5) Å; c = 6.8929(4) Å.
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