Rate of Propagation of Growth Layers on Cubic Crystal Faces in Electrocrystallization of Silver

Abstract

The advancement rate of mono‐ and polyatomic growth steps was measured on perfect, screw dislocation‐free cubic faces of silver single crystals during electrocrystallization of silver. For low overvoltages, a linear dependence of the rate on overvoltage was found. It was established that the advancement rate of the steps depends on the surface conditions of the crystal face and is about two times larger on a “fresh” surface than on an “aged” one. It was also found that mono‐ and polyatomic steps advance with the same rate on a fresh surface. A polyatomic step is considered as a ledge composed of monoatomic steps. The ledge spacing of this composite step was estimated. On the basis of these experimental results as well as on the experimentally determined value of the exchange current of adatoms with metal ions of the electrolyte, it is concluded that the electrolytic deposition of silver in 6M solution of silver nitrate is carried out according to the direct transfer mechanism. The value of the exchange current of the edge atoms at the steps with ions of the electrolyte was determined to be for an aged surface and for a fresh surface.