An overlayer on a substrate can be notated in either Wood's notation or matrix notation.
|
|
An overlayer is a layer of adatoms adsorbed onto a surface, for instance onto the surface of a single crystal.
|
|
Adsorbed species on single crystal surfaces are frequently found to exhibit long-range ordering; that is to say that the adsorbed species form a well-defined overlayer structure. Each particular structure may only exist over a limited coverage range of the adsorbate, and in some adsorbate/substrate systems a whole progression of adsorbate structure are formed as the surface coverage is gradually increased. The periodicity of the overlayer (which often is larger than that of the substrate unit cell) can be determined by low-energy electron diffraction (LEED), because there will be additional diffraction beams associated with the overlayer.
|
|
Jacques Doucet, 1898-1900, with characteristics of the aesthetic dress movement : simple in design, "yet extravagant by the choice of materials used. The sheer overlayer is enhanced by the solid lamé underlayers and a sense of luxury is added by the hidden lace flounce at the hem."Ball gown on Metropolitan Museum of Art. Oscar Wilde in his aesthetic lecturing costume, 1882.
|
|
They were brick-built, with a clay overlayer on the top side for the defense path. In the curtain wall interior there are rooms for accommodation of men and ammunition, as well as the workshops required for the Fortress functioning, with passages across the middle. Nowadays, in the reconstructed forge room in the west curtain wall, visitors of the Fortress can meet the Fortress blacksmith.
|
|
Structural reconstruction at the surfaces has been studied extensively by both theoretical and experimental methods. However, a question about surface stress is high enough to be a main driving force of the reconstruction is still not very clear. Most of metallic surface reconstruction exhibit in two genetic forms. On the original (100) surface, it would form a hexagonal overlayer which results in a considerably higher density of surface atoms by 20–25%.
|
|
Two different types of chemical etching have been reported. In the Turner method, a fiber is etched to a point while placed in the meniscus between hydrofluoric acid and an organic overlayer. This technique has been shown to produce fibers with large taper angles (thus increasing the light reaching the tip of the fiber) and tip diameters comparable to the pulling method. The second method is tube etching, which involves etching an optical fiber with a single-component solution of hydrogen fluoride.
|
|
Epitaxy refers to the deposition of a crystalline overlayer on a crystalline substrate, where there is registry between the two. In some cases epitaxial graphene layers are coupled to surfaces weakly enough (by Van der Waals forces) to retain the two dimensional electronic band structure of isolated graphene. An example of this weak coupling is epitaxial graphene on SiC and on Pt(111). On the other hand, the epitaxial graphene layer on some metals can be strongly bonded to the surface with covalent bonds.
|
|
Amorphous growth or multicrystalline growth with random crystal orientation does not meet this criterion. For most technological applications, single domain epitaxy, which is the growth of an overlayer crystal with one well-defined orientation with respect to the substrate crystal, is preferred. The term epitaxy comes from the Greek roots epi (ἐπί), meaning "above", and taxis (τάξις), meaning "an ordered manner". One of the main commercial applications of epitaxial growth is in the semiconductor industry, where semiconductor films are grown epitaxially on semiconductor substrate wafers.
|
|
There is a second type of electrotyping that has been used in which the copper film is deposited onto the outside of a form, and is not separated from it. In this use the form is typically waterproofed plaster, which remains as a core after electrotyping. In German this method is known as Kerngalvanoplastik; the more usual technique described in the previous paragraph is known as Hohlgalvanoplastik. Electrotyping is related to electroplating, which permanently adds a thin metallic overlayer to a metallic object instead of creating a freestanding metal part.
|
|
The external defense zone consisted of ravelins - triangular bastions protecting the main walls and obstructing the enemy access to the Fortress. All ravelins are constructed of rammed earth and brick walled on the outside, while in the upper part there is an overlayer and parapets. Within the west and east ravelin walls there is a redoubt - the pentagonal fortification used as a provisional powder magazine and as a gunsmith's. Due to the rapid development of the siege techniques, the Brod Fortress lost its defensive task already by the mid 19th century.
|
|
Epitaxy refers to a type of crystal growth or material deposition in which new crystalline layers are formed with one or more well-defined orientations with respect to the crystalline substrate. The deposited crystalline film is called an epitaxial film or epitaxial layer. The relative orientation(s) of the epitaxial layer to the crystalline substrate is defined in terms of the orientation of the crystal lattice of each material. For epitaxial growth, the new layer must be crystalline and each crystallographic domain of the overlayer must have a well-defined orientation relative to the substrate crystal structure.
|
|