Amorphous atomic structure

However, we do not know exactly to what extent simulated amorphous atomic structures depend upon the rate of quenching. It is known, for example, that in the ion implantation technique for the preparation of amorphous metals, one can achieve effective rates of cooling of 10 K/s (see, e.g. Ref. [15], p. 27) which is already close to that achievable in computer simulations. The resulting atomic structures are basically the same as those obtained by quenching techniques with six orders of magnitude smaller rates of cooling. 

A computer simulation of the surface of the amorphous Si02 has been reported in Ref. [16]. It was accomplished in two steps. First, the bulk amorphous atomic structure was simulated by the usual MD melt-quench technique described above. Then a free surface was created by removing the periodic boundary condition in one dimension (Z) and freezing the bottom layer of atoms. After that the system was annealed at 1000 K and then cooled gradually to 300 K. 

Some systematic deviations of simulated isotherms from experiment in the BET-region may be explained on assumption that real surfaces of amorphous oxide are characterized not just by the atomic roughness of the irregular amorphous atomic structure, but may also have another kind of roughness with a much larger scale of length. 

Material Aspects of Hydrogenated Amorphous Silicon 1.1.2.1. Atomic Structure... 

Natural diamond Natural graphite Synthetic diamond alloyed with iron, 23 248 in amorphous silica, 22 385 antimony impregnated, 3 53 atomic structure of, 22 232 biologically active, 17 803 as a blast furnace refractory,... 

When the surface is completely covered by an oxide film, dissolution becomes independent of the geometric factors such as surface curvature and orientation, which are responsible for the formation and directional growth of pores. Fundamentally, unlike silicon, which does not have an atomic structure identical in different directions, anodic silicon oxides are amorphous in nature and thus have intrinsically identical structure in all orientations. Also, on the oxide covered surface the rate determining step is no longer electrochemical but the chemical dissolution of the oxide.1... 

In order to discuss an essential feature of the laser-induced structural change, we mnst first consider the structure of amorphous films. Almost all available structural data indicate that the main constituent of a-Sbj Sei j (x < 0.05) is the chain mol-ecnle, althongh molecules with Sb branching sites may be contained in minority. That is, we assume that the local structure of a-Se containing Sb additives resembles the hexagonal (trigonal) Se structure. Accordingly, in atomic structural terms, a-Sbj Sci withx < 5at.% may be characterized as a quasi-one-dimensional chain structnre. 

Thin film technology is becoming one of the important technologies today. While there are infinite varieties of thin film fabrication methods, most amorphous thin films seem to exhibit fractal-like atomic structures. Depending on the fabrication conditions, a thin film grows on the substrate into columnar structures with many voids interdispersed in the thin film.80 These structures can be seen in the field ion microscope, and compositional variation can be analyzed with the atom-probe. In addition, formation of atomic clusters inside the thin film can be substantiated with the observation of a large fraction of cluster ions in field evaporation by the atom-probe. 

The breadth of X-ray reflections may be used to calculate crystal size within the range in which broadening occurs the method is mentioned in Chapter XI. The interpretation of amorphous patterns in terms of atomic structure is also referred to in the same chapter. 

As pointed out by Stephens and Goldman (State University of New York at Stony Brook). Quasicrystals are neither uniformly ordered like crystals nor amorphous like glasses. Many features of quasicrystals cun be explained, but their atomic structure remains to be described fully. See also Aluminum Alloys and Engineered Materials... 

A glass is an amorphous solid. How would the atomic structure of a glass differ from the particle structure of a crystalline solid ... 

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