Cleaved crystal faces

In uniform corrosion the superficial or geometrical area of the metal is used to evaluate both the anodic and cathodic current density, although it might appear to be more logical to take half of that area. However, surfaces are seldom smooth and the true surface area may be twice to three times that of the geometrical area (a cleaved crystal face or an electropolished single crystal would have a true surface area that approximates to its superficial area). It follows, therefore, that the true current density is smaller than the superficial current density, but whether the area used for calculating /, and... 

Prepared reactant freshly cleaved crystal face... 

Certain materials, most notably semiconductors, can be mechanically cleaved along a low-mdex crystal plane in situ in a UFIV chamber to produce an ordered surface without contamination. This is done using a sharp blade to slice tire sample along its preferred cleavage direction. For example. Si cleaves along the (111) plane, while III-V semiconductors cleave along the (110) plane. Note that the atomic structure of a cleaved surface is not necessarily the same as that of the same crystal face following treatment by IBA. 

An alkali halide (NaCl, KCl, KBr, etc.) which has a freshly cleaved (001) face is introduced into a polymer solution and then the pol5nner is to be crystallized epitaxially onto the face of the alkali halide. In general, flexible-chain polymers are apt to be crystallized as rod-like crystals on such an alkali halide these rod-like crystals are edge-on lamellae with their lateral surface being mostly in contact with the (001) face of the alkali halide. A given polymer deposited on an alkali halide can be melted and subsequently crystallized there in an epitaxial fashion. 

Production of a fresh surface in an ultrahigh vacuum by cleaving a single crystal. This method is limited to single crystals which permit cleaving in vacuum and is thus applicable only for certain crystal faces and to a relatively small number of cases. 

It is of considerable interest to learn if the surface structure of a cleaved crystal is similar to that of one cleaned by ion bombardment and annealing. An experiment of this type was first performed by Haneman (21) who made observations on the (0001) face of bismuth telluride. The results for the surfaces prepared by the two methods were... 

The collector [polished glass, cleaved mica, (100) face of a sodium chloride crystal, face of a metal, face of the metal] is maintained at a temperature below the melting point of the metal (in vacuum or in a neutral gas) so that crystal nuclei can be formed. The area of the film can reach several square centimeters. 

In fig. 77 we exploit the possibilities of a negative elastic constant. Boppart et al. (1980a) have glued strain gauges on the faces of a (100) cleaved crystal of IV TmSe... 

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