ИСТИНА

Electrodeposited palladium is of high importance due to its unique hydrogen-sorption and catalytic properties. Such properties could be adjusted, for example, by varying the electrodeposition potential [1] or introducing templating organic molecules [2]. Such an adjustment could significantly affect the texture of a metal [3]. Although systematic study of palladium electrodeposition from chloride baths and its adsorption properties was undertaken, so far no correlations between electrodeposition potential and palladium texture were derived. In this work, we studied systematically the dependence of palladium microstructure and texture on the electrodeposition potential. A set of films was deposited on gold-coated copper disks in a potentiostatic mode using a three-electrode electrochemical cell with a sacrificial Pd anode. Potential values were selected in a way that the set spans from the kinetic-control mode to the diffusion-control mode. Each sample was characterized by a set of techniques, including electrochemical (cyclic voltammetry, CO stripping), and X-Ray diffraction (Whole Powder Pattern Modelling, pole figures) methods. It was found that the electrodeposition potential, from a microstructural side, mainly affects a size of crystallites; it decreases two-fold when comparing lowest and highest deposition potentials. Dislocation density and stacking fault probability feature weak dependence on the deposition conditions. In contrast to what was found for other f.c.c. metals [3], no switching of the texture axis was observed even for high overpotentials, as all electrodeposits have (111) fiber axis; the width of texture peaks increase with increasing electrodeposition overpotential. [1] Yu. E. Roginskaya, E.N. Lubnin, T.Ya. Safonova, A.L. Chuvilin, E.D. Politova, and G.A. Tsirlina. Russ. J. Electrochem., 2003, 39, 283. [2] G.A. Tsirlina, O.A. Petrii, T.Ya. Safonova, I.M. Papisov, S.Yu. Vassiliev, and A.E. Gabrielov. Electrochim. Acta, 2002, 47, 3749. [3] N.A. Pangarov. J. Electroanal. Chem., 1965, 9, 70.