Face-centered cubic lattice structures

Zero-valent silver nanoparticles have also been synthesized using GSH as a surface passivant. Under standard reducing conditions, a preformed Ag(I)GSH complex was reduced to form nanoparticles of Ag°-(GSH). After isolation and purification of the nanoclusters, characterization showed a plasmon resonance band at 486 nm, a face-centered cubic lattice structure revealed by powder XRD, and a particle diameter of 8.6 3.5 nm by TEM. ... 

Additionally, Pt° nanoclusters were synthesized with glutathione as a ligand. Upon reduction of a preformed Pt(II)GSH complex, nanoparticulate material of PU-(GSH) was formed. These nanoparticles had an average diameter of 17.0 6.2 nm and demonstrated no plasmon absorbance due to the electronic and dielectric properties of the metal. Powder XRD analysis confirmed a face-centered cubic lattice structure for the material. ... 

The Rhj3 nuclear clusters have the structure of a face-centered cubic lattice structure with a rhodium atom coordination number equal to 12. These clusters are 4 nm in diameter. They interact with the protective polymer owing to electrostatic attraction or to physical adsorptioiL The formation of coordination bonds is also possiUe. 

The following generalizations may be made about the effects of low temperatures on the mechanical properties of metals, such as aluminum, which have face-centered, cubic lattice structures [10,11]. There is a small increase which is gradual and continuous in the initial resistance to deformation (yield strength) and in the elastic modulus as the temperature is lowered. There is little or no... 

In hydrates with their open structure the relative contribution of second and third neighbor solvent molecules to w(r) is only of the order of i of that in the much denser face-centered cubic lattice. It is therefore a better approximation to neglect second and third neighbors altogether than to use the functions derived by Wen tor f et al.u for the face-centered cubic lattice including contributions due to second and third shell neighbors. 

Magnesia forms solid solutions with NiO. Both MgO and NiO have face-centered cubic lattices with NaCl-type structures. The similarity between the ionic radii of the metals (Ni2+ = 0.69 A, Mg2+ = 0.65 A) allows interchangeability in a crystal lattice, and thus the formation of solid solutions with any proportion of the two oxides is possible. Such solid solutions are more difficult to reduce than NiO alone. Thus Takemura et al. (I) demonstrated that NiO reduced completely at 230°-400°C (446°-752°F) whereas a 10% NiO-90% MgO solid solu-... 

Hauke (1937) reported the same structure for NaZn13 and two other compounds (KZn13 and KCd13), and later (1938) for two more (RbCd13 and CsCd13). The structure is based on a face-centered cubic lattice. 

Figure 4.3.2 The diamond crystalline lattice structure composed of two interpenetrating face-centered cubic lattices.

Figure 5.18.1 The NaCl crystal structure consisting of two interpenetrating face-centered cubic lattices. The face-centered cubic arrangement of sodium cations (the smaller spheres) is readily apparent with the larger spheres (representing chloride anions) filling what are known as the octahedral holes of the lattice. Calcium oxide also crystallizes in the sodium chloride structure.

Figure 9.2 is schematic diagram of the crystal structure of most of the alkali halides, letting the black circles represent the positive metal ions (Li, Na, K, Rb, and Cs), and the gray circles represent the negative halide ions (F, Cl, Br, and I).The ions lie on two interpenetrating face-centered-cubic lattices. Of the 20 alkali halides, 17 have the NaCl crystal structure of Figure 9.1. The other three (CsCl, CsBr, and Csl) have the cesium chloride structure where the ions lie on two interpenetrating body-centered-cubic lattices (Figure 9.3). The plastic deformation on the primary glide planes for the two structures is quite different.

The fourth and final crystal structure type common in binary semiconductors is the rock salt structure, named after NaCl but occurring in many divalent metal oxides, sulfides, selenides, and tellurides. It consists of two atom types forming separate face-centered cubic lattices. The trend from WZ or ZB structures to the rock salt structure takes place as covalent bonds become increasingly ionic [24]. 

Stabilization of a Face-Centered-Cubic Mn Structure with the Ag Lattice Parameter. 

The clean siuface of solids sustains not only surface relaxation but also surface reconstruction in which the displacement of surface atoms produces a two-dimensional superlattice overlapped with, but different from, the interior lattice structure. While the lattice planes in crystals are conventionally expressed in terms of Miller indices (e.g. (100) and (110) for low index planes in the face centered cubic lattice), but for the surface of solid crystals, we use an index of the form (1 X 1) to describe a two-dimensional surface lattice which is exactly the same as the interior lattice. An index (5 x 20) is used to express a surface plane in which a surface atom exactly overlaps an interior lattice atom at every five atomic distances in the x direction and at twenty atomic distances in the y direction. 

Immediately after the isolation of macroscopic quantities of Cgo solid [298], highly conducting [299] and superconducting [141] behaviors were verified for the K-doped compounds prepared by a vapor-solid reaction (Haddon, Hebard, et al.). Crystallographic study based on the powder X-ray diffraction profile revealed that the composition of the superconducting phase is KsCeo and the diffraction pattern can be indexed to be a face-centered cubic (fee) structure with a three-dimensional electronic pathway [300]. The lattice parameter (a = 14.24 A) is apparently expanded relative to the undoped cubic Ceo = 14.17 A). The superconductivity has been observed for many A3C60 (A alkali metal), e.g., RbsCeo (Tc = 29 K... 

The crystal structure of the FenFem(CN)6 grouping is shown in Figure 37. A face-centered cubic lattice of Fe2+ is interlocked with another face-centered cubic lattice of Fe3 + to give a cubic lattice with the corners occupied by iron ions. The CN ions are located at the edges of the cubes between each Fe2+ ion and the neighboring Fe3 + the carbon atom of the cyanide is bonded to the Fe2 + ion and the nitrogen atom is coordinatively bonded to the Fe3 + ion. The alkali-metal ions and water molecules are inside the cubes formed by the iron ions. 

The sodium chloride structure. Sodium chloride crystallizes in a face-centered cubic structure (Fig. 4.1a). To visualize the face-centered arrangement, consider only the sodium ions or the chloride ions (this will require extensions of the sketch of the lattice). Eight sodium ions form the comers of a cube and six more are centered on the faces of the cube. The chloride ions are similarly arranged, so that the sodium chloride lattice consists of two interpenetrating face-centered cubic lattices. The coordination number (C.N.) of both ions in the sodium chloride lattice is 6. that is, there are six chloride ions about each sodium ion and six sodium ions about each chloride ion. 

After crystal structure II was deduced, a definitive x-ray diffraction study of tetrahydrofuran/hydrogen sulfide hydrate was undertaken by Mak and McMullan (1965), two of Jeffrey s colleagues. The crystal consists of a face-centered cubic lattice, which fits within a cube of 17.3 A on a side, with parameters as given in Table 2.2a and shown in Figure 1.5b. In direct contrast to the properties of structure I, this figure illustrates how a crystal structure may be completely defined by the vertices of the smaller 512 cavities. Because the 512 outnumber the 51264 cavities in the ratio 16 8, only 512 are clearly visible in Figure 1.5b. 

Silicon crystallizes in the diamond structure,16 which consists of two interpenetrating face-centered cubic lattices displaced from each other by one quarter of the body diagonal. In zinc blende semiconductors such as GaAs, the Ga and As atoms lie on separate sublattices, and thus the inversion symmetry of Si is lost in III-V binary compounds. This difference in their crystal structures underlies the disparate electronic properties of Si and GaAs. The energy band structure in... 

BaTiOs crystallizes in the perovskite structure. This structure may be described as a barium-oxygen face-centered cubic lattice, with barium ions occupying the corners of the unit cell, oxide ions occupying the face-centers, and titanium ions occupying the centers of the unit cells, (a) If titanium is described as occupying holes in the Ba-O lattice, what type of hole does it occupy (b) What fraction of the holes of this type does it occupy (c) Suggest a reason why it occupies those holes of this type but not the other holes of the same type ... 

Below 249 K, the molecules are orientated in an ordered fashion, and the symmetry of the crystal is reduced from a face-centered cubic lattice to a primitive cubic lattice. At 5 K, the crystal structure determined by neutron diffraction yielded the following data space group Pa3 (no. 205), a = 1404.08 (1) pm C-C bond lengths (6/6) 139.1 pm, (6/5) 144.4 pm, and 146.6 pm (mean 145.5 pm). 

Abstract. Gas interstitial fullerenes was produced by precipitation of C6o from the solution in 1,2 dichlorobenzene saturated by O2, N2, or Ar. The structure and chemical composition of the fullerenes was characterized by X-ray powder diffraction analysis, FTIR spectroscopy, thermal desorption mass spectrometry, differential scanning calorimetric and chemical analysis. The images of fullerene microcrystals were analyzed by SEM equipped with energy dispersive X-ray spectroscopy (EDS) attachment. Thermal desorption mass spectroscopy and EDS analysis confirmed the presence of Ar, N and O in C60 specimens. From the diffraction data it has been shown that fullerite with face centered cubic lattice was formed as a result of precipitation. The lattice parameter a was found to enhance for precipitated fullerene microcrystals (a = 14.19 -14.25 A) in comparison with that for pure C60 (a = 14.15 A) due to the occupation of octahedral interstices by nitrogen, oxygen or argon molecules. The phase transition temperature and enthalpy of transition for the precipitated fullerene microcrystals decreased in comparison with pure Cgo- Low temperature wet procedure described in the paper opens a new possibility to incorporate chemically active molecules like oxygen to the fullerene microcrystals. 

Apply reasoning analogous to that on page 319 to a face-centered cubic structure (for example, crystalline copper). Decide whether the reflections 100, 110, 111, 200, 220, and 222 should be present or absent. Check with the general statement given for face-centered cubic lattices on page 321. 

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