Nickel cubic crystal structure

NICKEL. [CAS 7440-02-0]. Chemical element, symbol Ni, at. no. 28. at. wt. 58.69, periodic table group 10, mp 1453rC, bp 2732°C. density 8.9 g/cm3 (solid, 20"C>. 9.04 g/cnr (angle crystal). Elemental nickel has a face-centered cubic crystal structure. Nickel is a silver-white metal, harder than iron, capable of taking a brilliant polish, malleable and ductile, magnetic below approximately 360°C. When compact, nickel is not oxidized on exposure to air at ordinary temperatures. The metal is soluble in HNO3 (dilute), but becomes passive in concentrated HNO3. The... 

Skutterudite is the name of a C0AS3-based mineral that was first extensively mined as a source of cobalt and nickel in the region of Skutterud Norway. Compounds with the same cubic crystal structure have since been known as skutterudites . Oftedal first extensively studied the skutterudite crystal structure in 1928 (Oftedal, 1928). An example of a well-formed natural skutterudite mineral is shown in fig. 1. 

In the present work, the interaction of the ethylene molecule with the (100) surfaces of platinum, palladium and nickel is studied using the cluster model approach. All these metals have a face centered cubic crystal structure. The three metal surfaces are modelled by a two-layer M9(5,4) cluster of C4V symmetry, as shown in Fig. 6, where the numbers inside brackets indicate the number of metal atoms in the first and second layer respectively. In the three metal clusters, all the metal atoms are described by the large LANL2DZ basis set. This basis set treats the outer 18 electrons of platinum, palladium and nickel atoms with a double zeta basis set and treats all the remainder electrons with the effective core potential of Hay and Wadt... 

The solid solution of carbon in the face-centered cubic crystal structure of iron. Austenite is only stable at high temperatures in ferritic steels but may be retained by fast cooling [retained austenite). In austenitic stainless steels it is stabilised at ambient and lower temperatures by the nickel in the steels. 

Stainless and heat-resisting steels containing at least 18% by weight chromium and 8% nickel are in widespread use in industry. The structure of these steels is changed from magnetic body centered cubic or ferritic crystal structure to a nonmagnetic, face-centered cubic or austenitic crystal structure. 

Nickel is known to have a face-centered cubic (fee) type of crystal structure. The atomic density of the metal is 9.14 X lO atoms/cm, the atomic weight is 58.73, and the density (p) is 8.91 g/cm. ... 

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. 

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. 

The crystal structures of metallic ruthenium and copper are different, ruthenium having a hexagonal close-packed structure and copper a face-centered cubic structure (7). Although the ruthenium-copper system can hardly be considered one which forms alloys, bimetallic ruthenium-copper aggregates can be prepared that are similar in their catalytic behavior to alloys such as nickel-copper (3,4,8). 

Cag.sNaAlgOis possesses an orthorhombic unit cell, space group Pbca. The mean A1—O bond length is 1.751(1) A, and the A1 atoms are distributed at positions very near the corners of pseudo-cubic sub-cells. The crystal structures of a number of nickel aluminosilicates have been determined. " ... 

The nickel aluminide NijAl - known as the y phase - crystallizes with the cubic LI2 structure (CujAu-type) which results from the fc.c. structure by ordering (see Fig. 1). Deviations from stoichiometry are accommodated primarily by antisite defects (Lin and Sun, 1993). The density of NijAl is 7.50 g/cm (see Liu et al., 1990) and thus is only slightly lower than that of the superalloys (see Table 2) which, however, is still of interest. The elastic constants have been studied experimentally and theoretically by various authors (e.g. Davies and Stoloff, 1965 Dickson et al., 1969 Kayser and Stassis, 1969 Foiles and Daw, 1987 Wallow et al., 1987 Yoo and Fu, 1991, 1993 Yasuda et al., 1991a, 1992). Young s modulus of cast polycrystalline NijAl at room temperature is about the same as that of pure Ni with a weaker temperature dependence (Stoloff, 1989),... 

The simplest crystal structures are cubic unit cells with only one atom centered at each lattice point. Most metals have such structures. Nickel, for example, has a face-centered cubic unit cell, whereas sodium has a body-centered cubic one. Figure 11.34 T shows how atoms fill the cubic unit cells. Notice that the atoms on the comers and faces do not lie wholly within the unit cell. Instead, these atoms are shared between unit cells. Table 11.6 summarizes the fraction of an atom that occupies a unit cell when atoms are shared between unit cells. 

Sumi et al. investigated the effect of the crystal structure of YSZ and ScSZ in nickel based anodes on the dynamics of carbon deposition and oxidation [108]. Anodes formed from YSZ-NiO and ScSZ-NiO were first characterised with Raman spectroscopy as a function of Ni content after calcination at 1673 K in air and at 1073 K in 10% H2/N2 mixed atmosphere. The Raman spectra suggested a mix of primarily cubic phase zirconia with a small contribution from other phases. The prevalence of cubic phase of ScSZ was found to be stronger than other phases compared to the YSZ based materials. The low solubility of Ni in ScSZ was observed to generate fine Ni particles on NiO reduction. The susceptibility of the different anode... 

Most metals fall in these three simple crystal structure categories. For example, V, Fe, Cr, Nb, and Mo have a body-centered cubic structure while Al, Ca, Ni, Cu, and Ag are face-centered cubic crystal systems and Ti, Zn, Co, and Mg are hexagonal close packed. The solubility of one metal into another to create alloys is greatly determined by the respective similarities between the crystal lattice of these metals and by other properties such as the size of the atoms. Noteworthy families of alloys made of iron (Fe, BCC), nickel (Ni, FCC), and chromium (Cr, BCC) are explained and described by their crystal structure as illustrated in Fig. 2.2. 

The nickel stabilizes the austenitic phase [y, face centered cubic crystal (fee) structure], at room temperature and enhances corrosion resistance. The austenitic phase formation can be influenced by both the Ni and Cr contents as shown in Figure 38.1 for 0.10% carbon stainless steels. The minimum amount of Ni for maintaining austenitic phase is approximately 10%. 

HGURE 11.56 Closest-Packed Crystal Structures in Metals Nickel crystallizes in the cubic closest-packed structure. Zinc crystallizes in the hexagonal closest-packed structure. 

For two metals to form a substitutional alloy, the radii of the two metal atoms must be similar, usually within 15% of each other. For example, the atomic radii of copper and nickel are both 135 pm, and both of the elements form the face-centered cubic structure. Therefore, either metal can easily replace the other in the metal crystal structure. 

Some alloys are composed of metals that have different crystal structures. For example, nickel crystallizes in the face-centered cubic structure and chromium in the body-centered cubic structure. Because of their different structures, these two metals do not form a miscible solid solution at all compositions. At some intermediate composition, the structure has to change from that of one of the metals to that of the other. Figure 23.7 shows the nickel and chromium phase diagram from 700 °C to 1900 °C. Notice that the diagram has two different solid phases face-centered cubic and body-centered cubic. From pure nickel (0 mol % chromium) to about 40-50 mol % chromium, the structure is face-centered cubic. 

The two aystals that exist at point A are (1) the nickel-rich face-centered cubic structure with 40 mol % Cr aud (2) the chromium-rich body-centered cubic structure with 5 mol % Ni. The 50% composition on the phase diagram has just slightly more Cr atoms thau can fit into the nickel structure. Thus most of the crystals in the two-phase region are the nickel-rich face-centered cubic structure with only a small amount of the chrominm-rich body-centered cubic structure, as determined by a method called the lever rule. The lever rule teUs us that in a two-phase region, whichever phase is closest to the composition of the alloy is the more abundant phase. In this example, the 50 mol % Cr composition on the phase diagram is closer to the 40 mol % Cr composition of the nickel-rich face-centered cubic phase than the 95 mol % Cr composition of the chromium-body-centered cubic phase, so more face-centered cubic crystals are present than body-centered cnbic crystals. 

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