NaCl type structure

The reference to the structure type may be a simpler and more convenient way of describing the structure of the specific phase. The structure type is generally named after the formula of the first representative identified the prototype . Expressions such as KC1 has the NaCl structure type are frequently used. Trivial names and symbols may also be found in several cases. 

Figure 3.38. Experimental densities of titanium oxides (continuous lines). The upper dotted line gives the values computed for a 100% occupancy of the cation sites in the NaCl structure type (from Hyde and Andersson 1989).

Sulphides. The partially ionic alkali metal sulphides Me2S have the anti-fluorite-type structure (each Me surrounded by a tetrahedron of S, and each S atom surrounded by a cube of Me). The NaCl-structure type (6/6 coordination) is adopted by several mono-sulphides (alkaline earth, rare earth metals), whereas for instance the cubic ZnS-type structure (coordination 4/4) is observed in BeS, ZnS, CdS, HgS, etc. The hexagonal NiAs-type structure, the characteristics of which are described in 7.4.2.4.2, is observed in several mono-sulphides (and mono-selenides and tellurides) of the first-row transition metals the related Cdl2 (NiAs defect-derivative) type is formed by various di-chalcogenides. Pyrite (cP 12-FeS2 type see in 7.4.3.13 its description, and a comparison with the NaCl type) and marcasite oP6-FeS2 are structural types frequently observed in several sulphides containing the S2 unit. 

Ce TeSb. The formation and crystal structure of CeTejcSbi- was studied by Ravot et al. (1982) and Rossat-Mignod et al. (1983) from the samples obtained by heating in molybdenum crucibles at 2273 K and slow cooling NaCl structure type, x = 0-0.5, a = 0.6422-0.6403. 

R-U-Sb. A NaCl structure type was observed for continuous solid solution Yi HJxSb alloys, x = 0-1, a = 0.6165-0.6208 by using X-ray powder diffraction method (Frick et al.,... 

We first experimented with the systems formed by yttrium sulfide (Y2S3) with the following divalent metal sulfides MgS, CaS, SrS, BaS, CrS, MnS, FeS, PbS, ZnS, and CdS (7, 8). From this preliminary study, we concluded that solid solutions can be observed only with the MS sulfides of the NaCl structural type MgS, CaS, SrS, BaS, MnS, and PbS. So we have continued our researches on the dia-... 

Note however, that all hydrides of the Group 1 elements actually adopt NaCl structure type. 

Two representatives of the NaCl structure type are diown in Table 8(b), namely InCl and lijTiOa, with very different types of qtlitting and different possibilities for the deformation of the octahedra. A further perovskite-like structure (index 64) is listed below ... 

Buerger, M.J. (1930) Translation-gliding in crystals of the NaCl structural type, Am. Mineral. 15, 174 and 226. 

The unit cell of AgCI (NaCl structure type) can he drawn with Ag+ ions at the corners of the cell, or Cl at the corners. Confirm that the number of Ag" and Cl ions per unit cell remains the same whichever arrangement is considered. 

Sodium fluoride adopts the NaCl structure type. Estimate the lattice energy of NaF using an electrostatic model. 

We can apply the Born-Haber cycle to a metal oxide having a structure type of known Madelung constant, and for which an electrostatic model is a reasonably valid approximation. Magnesium(II) oxide fits these criteria it has an NaCl structure type, /-Q has been accurately determined by X-ray diffraction methods, and compressibility data are available an electrostatic model gives At/(0K) = —3975kJmol . All other quantities in the appropriate Bom-Haber cycle are independently measurable and a value for E Aea (298 K) for reaction 6.21 can be evaluated. A series of similar values for E Aea- °(298 K) for reaction 6.21 can be obtained using different group 2 metal oxides. 

In a Frenkel defect, an atom or ion occupies a normally vacant site, leaving its own lattice site vacant. Figure 6.27 illustrates this for AgBr, which adopts an NaCl structure type. In Figure 6.27a, the central Ag+ ion is in an octahedral hole with respect to the fee arrangement of Br ions. Migration of the Ag ion to one of the previously unoccupied... 

Explain what is meant by Frenkel and Schottky defects in an NaCl structure type. 

Intermetallic compounds of scandium with the 6B elements Se, Te and Po are different compared to all of the previously described scandium compounds. They crystallize in structures typical for oxides, sulphides and other ionic compoimds (AlaMgOq, FeaCaOq, ErCuS2, ErAgAs, NaCl structure types). In these structure types each atom is coordinated... 

At room temperature DySe crystallizes in the cubic NaCl structure type. Lattice constants between 5.705 and 5.713 A are reported, see Section 29.1.2.1.1, p. 7. 

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