INVESTIGATION OF STRUCTURE AND COMPOSITON OF IrO₂ - Ta₂O₅ SURFACE LAYERS. J. Krysa^1, J. Maixner^{2, 1}Department of Inorganic Technology, ²Central Laboratories, Institute of Chemical Technology, Technicka 5, 166 28 Prague 6, Czech Republic

IrO₂ - Ta₂O₅ coating is so far the best electrocatalyst for an oxygen evolution (1). Therefore, the structure and composition of the IrO₂ - Ta₂O₅ thermally deposited surface layers on Ti substrate were investigated by X - ray diffraction and electron microscopy.

X - ray diffraction revealed the crystalline form of IrO₂ and the amorphous form of Ta₂O₅ in the coating. The average coating thickness was calculated from the decrease of Ti substrate intensities using 2 methods and it is proportional to the deposited iridium content. The X-ray intensities of IrO₂ coating show the same dependence.

From analysis of microphotographs of IrO₂ - Ta₂O₅ surface layer it is apparent that the mixture of both oxides is uniformly distributed over the surface area.

(1) R. Mráz and J. Krysa, J. Appl. Electrochem., 24, 1262 (1994)

(2) R. Kuzel Jr.:Difpatan, Program for X-ray analysis, Charles University, Czech Republic