Copper cubic crystal structure

A ternary compound of cerium with copper and antimony of the stoichiometric ratio 3 3 4 was identified and studied by means of X-ray analysis by Skolozdra et al. (1993). Ce3Cu3Sb4 compound was found to have the Y3Au3Sb4 type with the lattice parameters of a = 0.9721 (X-ray powder diffraction). For experimental details, see the Y-Cu-Sb system. At variance with this data, Patil et al. (1996) reported a tetragonal distortion of the cubic crystal structure Y3Cu3Sb4 for the Ce3Cu3Sb4 alloy which was prepared by arc melting the constituent ele-... 

Morreale et al. find that 80 wt%> Pd-20 wt% Cu alloys exhibit higher resistance to H2S (at very high partial pressures of hydrogen) relative to the 60 wt% Pd-40 wt% Cu composition [77]. However, the 80-20 composition has a lower initial (unpoisoned) permeability relative to the 60—40 composition. The 80-20 Pd-Cu composition has the face centered cubic crystal structure as do unalloyed elemental palladium and copper [77]. 

The copper atom has a single valence electron in its 4s subshell, and this electron is loosely bound. The solid metal consists of positive ion cores, Cu+, at regular sites, in the face-centered cubic crystal structure. The valence electrons detach themselves from their parents and wander around freely in the solid, forming a kind of electron cloud or gas. These mobile electrons are free to respond to an applied held, creating a current density /j..The valence electrons in the electron gas are therefore conduction electrons. 

The differing malleabilities of metals can be traced to their crystal structures. The crystal structure of a metal typically has slip planes, which are planes of atoms that under stress may slip or slide relative to one another. The slip planes of a ccp structure are the close-packed planes, and careful inspection of a unit cell shows that there are eight sets of slip planes in different directions. As a result, metals with cubic close-packed structures, such as copper, are malleable they can be easily bent, flattened, or pounded into shape. In contrast, a hexagonal close-packed structure has only one set of slip planes, and metals with hexagonal close packing, such as zinc or cadmium, tend to be relatively brittle. 

The ruthenium-copper and osmium-copper systems represent extreme cases in view of the very limited miscibility of either ruthenium or osmium with copper. It may also be noted that the crystal structure of ruthenium or osmium is different from that of copper, the former metals possessing the hep structure and the latter the fee structure. A system which is less extreme in these respects is the rhodium-copper system, since the components both possess the face centered cubic structure and also exhibit at least some miscibility at conditions of interest in catalysis. Recent EXAFS results from our group on rhodium-copper clusters (14) are similar to the earlier results on ruthenium-copper ( ) and osmium-copper (12) clusters, in that the rhodium atoms are coordinated predominantly to other rhodium atoms while the copper atoms are coordinated extensively to both copper and rhodium atoms. Also, we conclude that the copper concentrates in the surface of rhodium-copper clusters, as in the case of the ruthenium-copper and osmium-copper clusters. 

To illustrate this, take the situation in a very common and relatively simple metal structure, that of copper. A crystal of copper adopts the face-centered cubic (fee) structure (Fig. 2.8). In all crystals with this structure slip takes place on one of the equivalent 111 planes, in one of the compatible <110> directions. The shortest vector describing this runs from an atom at the comer of the unit cell to one at a face center (Fig. 3.10). A dislocation having Burgers vector equal to this displacement, i <110>, is thus a unit dislocation in the structure. 

Figure 3.11 Cubic close-packed structure of face-centered cubic crystals such as copper as a packing of atom layers (a) a single close-packed layer of copper atoms (b) two identical layers, layer B sits in dimples in layer A (c) three identical layers, layer C sits in dimples in layer B that are not over atoms in layer A. The direction normal to these layers is the cubic [111] direction.

Copper(II) oxide is found in nature as the minerals tenorite and paramela-conite. They differ in crystalline structure tenorite exists as triclinic crystals while paramelaconite consists of tetrahedral cubic crystals. 

When we determined the crystalline structure of solids in Chapter 4, we noted that most transitional metals form crystals with atoms in a close-packed hexagonal structure, face-centered cubic structure, or body-centered cubic arrangement. In the body-centered cubic structure, the spheres take up almost as much space as in the close-packed hexagonal structure. Many of the metals used to make alloys used for jewelry, such as nickel, copper, zinc, silver, gold, platinum, and lead, have face-centered cubic crystalline structures. Perhaps their similar crystalline structures promote an ease in forming alloys. In sterling silver, an atom of copper can fit nicely beside an atom of silver in the crystalline structure. 

Just as the body-centered cubic structure can be considered as made of two interpenetrating simple cubic lattices, the face-centered cubic structure can be made of four simple cubic lattices. There are some interesting cases of ordered alloys with this crystal structure and ratios of approximately one to three of the two components. An example is found in the copper-gold system, where such a phase is found in the neighbor-... 

When the a phase, i.e, the primary solid solution, has only a limited range of stability, other intermediate phases are formed. At particular concentrations of the second component a transformation from one crystal structure to another takes place. In a large number of binary systems, e.g. Gu-Au, Cu-Al, Cu-Sn, a transition from the cubic close packed structure of copper to a body centred cubic structure ()3 phase) occurs at a particular concentration. The phase is stable over a particular range of concentration and at higher concentrations is generally converted to the y-phase which has a complex structure, followed by the e and >) phases which are... 

With the exception of manganese and urauium, all true metals have one of the following crystal structures body-centered cubic (sodium, potassium, molybdenum), iron face-centered cubic (copper, silver, gold), iron close-packed hexagonal (beryllium, magnesium, zirconium). 

Metal oxide nanocomposites were synthesized by electrical discharge method using a combination of aluminum and copper electrodes submerged into water. The crystal structure, lattice parameters and grain size of the nanopowders were determined by XRD using Cu K radiation (Fig. 3b). The XRD pattern exhibited the presence of cubic copper with a lattice constant of 0.3615 nm, as well as aluminum and copper oxide and hydroxide phases. The positions of all peaks were in agreement with the JCPDS standards. 

The metals aluminum, nickel, copper, and silver, among others, crystallize in the face-centered cubic (fee) structure shown in Figure 21.13. This unit cell contains four lattice points, with a single atom associated with each point. No atom lies wholly within the unit cell there are atoms at the centers of its six faces, each of which is shared with another cell (contributing 6 X y = 3 atoms), and an atom at each corner of the cell (contributing 8 X = 1 atom), for a total of four atoms per unit cell. 

For example, the experimentally measured density of copper is 8.92 g/cm, the unit cell dimension of its cubic unit cell is a = 3.615 A, and the molecular mass of a formula unit is 63.55 a.m.u., which is the molar mass of copper, one atom per formula unit. Thus, Eq. 6.4 results in Z = 3.99 4 atoms per unit cell. The same equation may be used to calculate the density of a material when its crystal structure has been established. It is worth noting that the computed value of the material s gravimetric density is known as the x-ray density, and it is usually slightly higher than the measured density because real materials always have some defects and porosity that are not accounted in Eq. 6.4. 

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