Copper lattice

Epitaxial coherency maintained for the three low-index orientations of the fee copper lattice substrate to various degrees. 

Robinson and Torrens have discussed the limitation of the binary-collision approximation. They concluded, for example, that it was likely to fail at energies below 9 eV for collisions between copper atoms in a copper lattice and below 33 eV for gold atoms in a gold lattice. Therefore, phenomena which depend sensitively upon motions of particles with very low energy are likely to be described only qualitatively by the binary collision model. 

The mutual solubilities of metals are not reciprocal. A metal of low valency is more likely to dissolve one of higher valency than vice versa. For example, in the solid solutions of copper and silicon, a silicon atom may replace four copper atoms in the copper lattice, but a copper atom, with only a single valency electron, cannot replace a silicon atom which is linked tetrahedrally with four other silicon atoms. Hence the solubility of silicon in copper is 14 per cent but that of copper in silicon only 2 per cent. In a similar way tin dissolves only I per cent of silver whereas silver can dissolve up to I2 2 per cent of tin. 

Fig. 2.—Expansion of copper lattice compared with methyl formate production (dotted), both as functions of catalyst composition in the decomposition of methanol over Zu-Cu catalysts."...

The foregoing considerations become modified for certain systems, especially those of more than one component, such as alloys, and here a special kind of change, known as an order-disorder transition, can occur. The phenomena shown by the alloy of copper and zinc known as jS-brass will introduce us to a matter of some general importance. At low temperatures the alloy consists of a regular lattice of copper atoms, one at each corner of a series of cubes, and of a similar lattice of zinc atoms, so disposed that each cube of the copper lattice has a zinc atom at its centre and each cube of the zinc lattice a copper atom. The two interpenetrating simple cubic lattices thus give what is called a body-centred cubic lattice. 

The formula Cu i Zn describes the composition. The structure of pure copper (x = 0) is the face centered cubic lattice (fee, Pearson symbol cF4). Upon an increase in the zinc concentration, a solution of zinc in copper is observed (a-phase). The solubility extends up to X = 0.38 depending on the temperature. The zinc atoms are statistically distributed in the copper lattice. 

Copper has an fee lattice. The unit cell is described in the original model by its electronic structure 4Cu (d °), Icocu Half of the octahedral interstitial sites and a quarter of the tetrahedral sites are filled with free electrons. The copper lattice has Cu" cations. 

Figure 11.1. Nuclei of CujO formed on copper surface at 10" mmHg oxygen pressure (13.3Pa), 525°C, 20s (17,600x). Black lines are bands of imperfections (stacking faults) in the copper lattice (Brockway and Rowe [5]).

From investigations of the active phase of a bulk metallic copper catalyst under reaction conditions of the partial methanol oxidation by means of in situ XAS at the oxygen K-edge and copper L2-,L3-edges it was concluded that the partial oxidation of methanol to formaldehyde is catalysed by a copper plus oxygen phase where oxygen atoms probe defects of tiie copper lattice, which represent the catalytically active sites [3, 4, 6j. 

By differentiating the XANES spectra, it was identified that the intensity of the edge absorption for the catalyst was lower than that for copper foil, consistent with the nanosized dimension of the copper particles. Moreover, the positive shift of the derivative peaks at ca. 8990 and 8984 eV relative to those of copper foil suggested some alterations in the chemical environment around the copper species. Combined with the XRD results, the positive shift was tentatively assigned to a distortion of the copper lattice due to the presence of microstrain at the interface between Cu NPs and ZnO NRs. Consequently, the superior catalytic performance of the ZnO NR Cu NPs catalyst in methanol reforming was attributed to the enhanced dispersion of Cu NPs and the existence of the SMSl effect. 

With the development of the electronic industry, copper has been one of the important materials in many fields such as electrical interconnects, and in the past decade, which has been of significant interest to many researchers I22-27].ln our simulations of nano-machining and nanostructures, we also considered the monocrystalline copper and pyramid rigid diamond as the workpiece and tool, respectively, as shown in Fig.l. The initial atomic configuration of the workpiece material is created from the face-centred cubic (FCC) copper lattice and the tool is tri-pyramid diamond tip with a rake angle of -60°. The atoms of workpiece are divided two parts. The upper part of workpiece is made of the 36 layers newtonial atoms and the atoms of surfaces are free, while the bottom of workpiece is made of the 4 layers boundary atoms and atoms are fixed in space at the process of scratching. The sizes of slab at x[l 0 0], y[0 1 0] and z[0 0 1] direction are 30, 17 and 18ao, where ao is the equilibrium lattice constant (for FCC Cu, ao = 362 nm). 

It could be supposed that the first stages of Cu and Sn codeposition occurring at E < involve the underpotential deposition of tin on foreign (copper) lattice. In... 

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