The phenomenon of epitaxy

The consideiation on the jumps requires certain continuity between the two lattices of the solids M and MG this phenomenon is known as epitaxy . 

The formed solid has its own stmcture, but the interatomic distances are not those of its normal phase they are adapted as compared to the distances that exist in the initial solid. This phenomenon often occurs in experiments each time a solid layer grows on a solid support and, in particular, for thin layers created in heterogenous reactions [BEN 62]. 

In both the cases, we can assume that there is continuity in the lattice for representing the equations for the elementary jumps at the solid-solid interfaces. 

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The work of adhesion is also related to the force needed to break chemical bonds at the interface on the atomic scale. When bonds form at the interface of two solids, restructuring can occur at both sides of the interface, thereby optimizing the strength of the interfacial chemical bond. This restructuring is related to the adsorbate-induced restructuring processes and to the phenomenon of epitaxy that was discussed in Chapters 2 and 5. It involves the movement of atoms perpendicular, as well as parallel, to the interface. We may call this movement the work of interface restructuring It involves surface atoms as well as atoms two to three layers away from... 

The structure of such precipitates can be influenced by the carrier. Thus, oriented deposits are known in which the crystallites of the deposit are preferentially attached to a specific crystal plane of the carrier. Further, there exists the phenomenon of epitaxy, in which the crystal axes of the individual deposit particles have a definite spatial and geometric relationship to each other and to the crystal axes of the carrier. Under such conditions, there may occur significant changes in the relative proportions of some crystal surfaces to the total surface area. Precipitation on a surface is not necessarily preceded by a chemical reaction. 

The phenomenon of epitaxy takes place if the lattice geometry of the different crystals is similar. In a first approximation, it is obvious that epitaxy takes place if the difference between the lattice parameters is less than 15%. 

In our opinion, the phenomenon of the heterogeneous melting allows one to understand the vapor-liquid-solid mechanism of epitaxy, which occurs at a temperature below the reference melting temperature, and the mechanism of layer-by-layer growth of crystals. 

Oriented ultrathin overgrowth of a polymer on a non-polymeric substrate is the latest combination of materials to show epitaxy. The most recent, remarkable form of this phenomenon is the formation of an array of parallel polymer chains on a substrate by depositing monomers and then polymerising them in situ. The Japanese discoverer of this phenomenon (Sano 1996) has called it polymerisation-induced... 

Epitaxy the phenomenon whereby a deposit or coating takes up the lattice habit and orientation of the substrate. 

Coaxial intergrowth is a paragenetic relation that describes crystals of two different species growing with a common axis the misfit ratios between the two crystals in the direction of the common axis are small, without exception. The formation of coaxial intergrowth can be understood to be one crystal conjunct to the other in an epitaxial relation, where both continue to grow. If a liquid of eutectic A-B component is solidified from one side (unidirectional solidification), crystals of the two phases A and B precipitate in dotted, columnar or lamellar (with common axis) form, and show unique textures for unidirectional solidification. This is a well known phenomenon in metallurgy. 

The atomistic theory becomes of additional significance for the transition from 2D Me phase formation in the UPD range to 3D Me phase formation in the OPD range. Experimental results obtained using modern in situ techniques with lateral atomic resolution showed that the transition phenomena can only be interpreted on the basis of atomistic approaches. The UPD surface modification turns out to be a more general phenomenon affecting not only the nucleation processes but also the growth mode and epitaxy of 3D metal phases. 

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