NaCl-CsCl

Crystal structure Distorted NaCl CsCl CsCl See text... 

We have touched briefly on three simple ionic lattices, but there are many others. Moreover, the stmctures of many crystalline network solids can also be described by the methods we have introduced here for NaCl, CsCl, and CaF2. 

The coordination numbers of the atoms increase from 6 to 8 in the NaCl —> CsCl type conversion therefore, it is a reconstructive phase transition which can only be a first-order transition. 

Figure 2.5. Simplified version of Pettifor s map for AB compounds. The component elements are arranged along the axes according to their Mendeleev number (M). As an example, the existence regions of the NaCl, CsCl and cubic ZnS type phases are evidenced.

Figure 4.22. Space-filling curves for compounds having the NaCl, CsCl, NaTl or ZnS type structures. For the different structures, the ratio

The ten most commonly occurring structure types in order of frequency are NaCl, CsCl, CrB, FeB, NiAs, CuAu, cubic ZnS, MnP, hexagonal ZnS, and FeSi respectively. Structures cF8 (NaCl) and cP2 (CsCl) are ordered with respect to underlying simple cubic and body-centred cubic lattices respectively, as is clear from Figs 1.10(a) and 1.11(a). The Na, G sites and Cs, Cl sites are, therefore, six-fold octahedrally coordinated and fourteen-fold rhombic dodecahedrally coordinated, respectively, as indicated by the Jensen symbols 6/6 and 14/14. 

While radius ratio rules generally predict correct structure types for the alkali halides in only about 50% of the cases, the MEG calculations (not even shell stabilized) correctly predict the NaCl structure to be more stable for 15 of the 16 compounds studied. Calculated structural parameters were also in good agreement with experiment, and calculated pressures for the NaCl CsCl transition were in fair agreement with the limited experimental data available. These results indicate that preferred coordination numbers and structural types in alkali halides can be accu-... 

Each compound has either the NaCl, CsCl, or ZnS type cubic structure. Predict the type of structure formed (NaCl, CsCl, or ZnS), the type and fraction of holes filled by the cations, and estimate the density of each compound. 

The Structures of Chapter 4 considered the topic of simple ionic compounds such as NaCl, CsCl, Cap2,... 

ZnS, SiOg and Cdig the division of the crystal into single molecules is impossible. Only in TiOg is there a suggestion of a molecular unit. Such formulae as NaCl, CsCl etc thus represent the ratio of the different species of atoms or ions present in the crystal and not the formula of a single molecule. We must now consider the nature of the forces producing the various crystal structures. 

He used the B. xyz) so obtained to calculate very accurately the Made-lung constants for the cubic lattice t3rpra NaCl, CsCl, ZnS, CaF2 and CU2O. Relations between various grundpotentials have been shown to exist by Hund (55), by Emersleben SS) and by Sakamoto 111) who has summarized them and recalculated a number of Emersleben s original values. 

LiCl-NaCl-CsCl LiCl,NaCl, LiCl,2NaCl, LiCl.CsCl (d. 352 °C), LiCl,2CsCl (d. 382 °C) 309... 

NaCl CsCl CaFs Zinc Blende Wurtzite 1.74756 1.76267 5.03878 1.63805 1.64132... 

AI2O3 Merck, washed 10 mol dm" NaCl. CsCl, LiCl 25... 

PZC at the same pH in the presence of NaCl, CsCl, NaNO., KNO,. and CsNO, is reported in the conclusion. 

Shchiikarcv, A.V., A study of the SiOj-aqueous electrolyte (NaCl, CsCl) interface by X-ray photoelectron spectroscopy. Colloid J., 69, 514, 2007. 

Table 2 shows the effects of NaCl, CsCl, and various lithium-salts on the reaction over NiO. It is obvious that alkali-halides such as LiCl, LiBr and NaCl exert favorable effect on the selective formation of C2H4. Moreover, it should be noted that addition of any kinds of alkali metal salts improved... 

However, let us return to the solubility data in caesium iodide-melt at 700 °C. It can be seen that the oxide solubilities in this melt are intermediate between those in KCl-NaCl (CsCl-KCl-NaCl) and CsBr-KBr melts. Since for the said iodide-melt the range of oxides suitable for the investigations is too small, compared with other halides, and the range of solubilities is too narrow, some of the correlations considered above have not been analysed for molten Csl. Nevertheless, for chloride, bromide and iodide-melts, linear correlations between pPMe0 and rk 2 can be found, and the corresponding parameters of equation (3.7.16), with their confidence ranges, are presented in Table 3.7.16. 

C) and molten CsCl-KCl-NaCl and KCl-LiCl eutectic mixtures at 800 °C. The solubility parameters obtained are collected in Table 3.7.20, where the oxoacidic properties of the chloride melts reduce when moving from the top to the bottom. From the data cited here, it follows that the solubility products of MgO increase with the substitution of the low-acidic constituent cation by that possessing enhanced acidic properties. The same can be said for the increase in the concentration of the constituent acidic cation in the melt there is an increase in the MgO solubility in the sequence, KCl-CsCl-KCl-NaCl(CsCl)-NaCl, where the concentration of Na+ and hence the melt acidity, increases. 

With reference to the NaCl, CsCl and Ti02 lattice t5q)es, explain what is meant by (a) coordination number, (b) unit cell, (c) ion sharing between unit cells, and (d) determination of the formula of an ionic salt from the unit cell. 

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