Metal atomistic aspects

In this chapter we derive the Butler-Vohner equation for the current-potential relationship, describe techniques for the study of electrode processes, discuss the influence of mass transport on electrode kinetics, and present atomistic aspects of electrodeposition of metals. 

In the discussion of atomistic aspects of electrodepKJsition of metals in Section 6.8 it was shown that in electrodeposition the transfer of a metal ion M"+ from the solution into the ionic metal lattice in the electrodeposition process may proceed via one of two mechanisms (1) a direct mechanism in which ion transfer takes place on a kink site of a step edge or on any site on the step edge (any growth site) or (2) the terrace-site ion mechanism. In the terrace-site transfer mechanism a metal ion is transferred from the solution (OHP) to the flat face of the terrace region. At this position the metal ion is in an adion state and is weakly bound to the crystal lattice. From this position it diffuses onto the surface, seeking a position with lower potential energy. The final position is a kink site. 

Section 3.1.2 discusses metal/metal-ion interphase at equilibrium Sect. 3.1.3 discusses the relationship between current and potential Sect. 3.1.4 describes the atomistic aspects of electrodeposition and Sect. 3.1.5 presents the techniques for studying deposition processes. 

In the discussion of atomistic aspects of electrodeposition of metals, Sect. 3.1.5, it was shown that in the electrodeposition the transfer of a metal ion M"+ from the solution into the ionic metal lattice in the electrodeposition process may proceed via one of the following two mechanisms ... 

From atomistic aspects, a metal can be considered as a fixed lattice of positive ions permeated by a gas of free electrons [1], Positive ions are the atomic cores, while the electrons are the valence electrons. Since there are about 1022 atoms in 1 cm3 of a metal, one can expect that some atoms are not exactly in their right place. Thus, one can expect that a real lattice will contain defects (imperfections). The most common defects are point defects (e.g. a vacancy, an interstitial) and dislocations (e.g. the edge dislocation, screw dislocation) [2]. 

And, yet, the transcendental aspect of elements was not completely forgotten and continued to serve an explanatory function in nineteenth-century chemistry but not necessarily a microscopic explanation. A chemist could be skeptical of atomistic explanations, as many were in the nineteenth-century, and yet could readily accept a transcendental explanation, for example, for the persistence of the elements in their various compounds. As was alluded to earlier, one of the benefits of regarding the elements as having a transcendental existence is that it provides a way out of the apparent paradox concerning the nature of elements when combined in compounds. Suppose that sodium and chlorine are combined to form sodimn chloride (common salt). In what sense is the poisonous metal sodium present in a sample of white crystalline common salt Similarly, one may ask how it is that the element chlorine, a green and poisonous gas, continues to exist in common salt. Clearly, the elements themselves, in the modern sense of the word, do not appear to survive, or else they would be detectable and one would have a mixture of sodium and chlorine able to show the properties of both these elements. The response available from the nineteenth-century element scheme is that simple substances do not survive in the compound but abstract elements do. ... 

The detailed study of molecular mechanisms involved in adhesion requires an atomistic treatment of the substrate surfaces and their interaction with the organic components contained in the adhesive. Interesting aspects of the substrate-adhesive interaction include the preferential molecular orientation due to the interaction at the surface [1] or the influence of the initial stages of polymer grafting on the stability of polymer/metal interfaces [2]. The structure and composition of the interface can have a decisive effect on the properties of the re-... 

Electronic properties of nanocrystals critically depend on size. This aspect is aptly put forth in the quest How many atoms make a metal . It is clear that as the size of metal nanocrystals is reduced, the accompanjung changes in the electronic structure render them insulating. This transition, called the size-induced metal-insulator transition (SIMIT), has evoked much interest from chemists and physicists alike. A SIMIT is manifested in experiments that measure the electronic band structure and atomistic properties such as ionization energy. 

K. Sieradzki, Atomistic and micromechanical aspects of environment induced cracking of metals. Proceedings of First International (Conference on Envirorunent Induced Cracking of Metals, Kohler, Wisconsin, NACE, October 1988, pp. 125-138. 

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