Preferred orientation of nickel electro-deposits: III. Generalization of the theory

Abstract

This paper discusses the lines along which the proposed theory of texture development (for nickel electro-deposits) can be extended to include (a) lateral growths, (b) deposits of other metals and (c) deposits from adulterated baths. It suggested that when deposits adopt the lateral mode of growth, the slowest-growing {hkl} facets are formed - in the ideal case - parallel to the substrate. The normal to these facets becomes the texture-axis. In practice, the {hkl} facets may deviate from parallelism and the texture-axis then develops a scatter from its ideal position. The theory can be generalized to cover other metals by using the fact that surface coverage with hydrogen atoms depends on the heat of hydrogen adsorption which varies from metal to metal. Hence, the textures of Pb, Ag and Cu should correspond more to free growth orientations, whereas those of Fe and Co should be coverage-dependent like Ni. The many ways in which addition agents can influence textures are indicated. Addition agents can influence, for instance, the hydrogen evolution reaction, the nucleation rate and the mode of growth. Their differential adsorption on different facets and their surface activity are also discussed.