The role of crystal imperfections in electrochemical phase formation and growth

Abstract

The role of different crystal imperfections and surface inhomogeneities in the processes of electrochemical phase formation and crystal growth is discussed on the basis of experimental results obtained by electrodeposition of metals on native and foreign single crystal substrates in selected model systems. The major role of screw dislocations in the electrochemical growth of real crystals is demonstrated in the case of silver electrodeposition on silver single crystal faces prepared by the so-called capillary technique. Experimental results show that the electrochemical spiral growth of silver crystal faces with low dislocation density can be used for a preparation of surfaces with a defined and uniform density of monatomic steps. Combined electrochemical and in situ scanning probe microscopy (SPM) studies of underpotential deposition (UPD) of metals on foreign single crystal substrates show that surface inhomogeneities induce a stepwise formation of different low-dimensional (0D, 1D, and 2D) metal phases. The thermodynamic, kinetic, and structural aspects of the stepwise formation of Me phases of different dimensionality in the UPD range are discussed on an atomic level using results of electrochemical and in situ SPM measurements in various systems. Keywords: electrocrystallization, screw dislocations, spiral growth, surface inhomogeneities, underpotential deposition, low-dimensional phases, scanning tunneling microscopy.