Effect of Sn-precursor on the morphology and composition of Ir0.3Sn0.7O2 oxide films prepared by sol-gel process

With the aim of investigating the effect of the type of Sn-precursor on the physical-chemistry properties of iridium dioxide coatings, electrodes of I r0.3Sn0.7O2 nominal composition were prepared by the sol-gel technique as a n alternative to the classical thermal procedure. The influence of the Sn-p recursor on the surface properties of these electrode materials was investi gated by scanning electron microscopy, energy-dispersive X-ray and X-ray di ffraction and cyclic voltammetry. The colloidal dispersion was prepared by refluxing (46 h, 80 degrees C) a mixture in the appropriate proportion of p recursors, Oxide films were deposited on Ti-subtracts by thermal decomposit ion (400 degrees C, 1h, 51 min(-1) O-2 flux) Of colloidal dispersion. An ex pressive difference was observed in the morphology of the oxide layer with the change of the type of Sn-precursor. The X-ray diffractogram of the SnCl 2-precursor film had only broad peaks indicating the amorphous state of the oxide mixture. While the [CH3(CH2)(3)](3)SnOC2H5-precursor film had diffra ction peaks due to SnO2 rutile structure and reflections due to iridium met al in addition to Ir hydroxyoxide phase. The cyclic voltammetric data are c onsistent with the surface analysis results. Independently of the Sn-precur sor adopted, the actual composition of the layer is close to nominal showin g the sol-gel procedure is more efficient than the thermal decomposition pr ocedure to obtain Sn containing with this property. (C) 2000 Elsevier Scien ce B.V. All rights reserved.