Sol–gel preparation and characterisation of mixed metal tin oxide thin films

Mixed metal oxide stannates were prepared by sol–gel methods and coated onto solid titanium substrates as thin films using spin and dip coating methods. Metal oxides such as Sb2O5, ZrO2, CuO, MnOx and PdO were introduced into a SnO2 host matrix using sol–gel technology. The mixed metal tin oxide materials prepared via the sol–gel route were extensively characterised in terms of surface characterisation and chemical composition. Thermogravimetric analysis was performed to confirm that at 600 °C (the calcination temperature) no further structural changes due to mass loss occur. UV spectroscopy of the liquid gels allowed the determination of the band gap energy. The surface morphology of the thin film electrodes were characterised by atomic force microscopy and scanning electron microscopy and the effect of the coating method employed i.e. spin or dip coating could be clearly seen in the estimated values of surface roughness. These techniques were also able to confirm the thickness of the films in the nano range. Combined nuclear beam techniques such as Rutherford backscattering spectroscopy and particle induced X-ray emission provided some insight into the chemical composition of the mixed metal tin oxides and confirmed the presence of the dopant element in the SnO2 host material.