NaCl structure

Cobali [[) oxide, CoO. Olive green solid (heat on Co(OH)2 or cobalt(Il) oxyacid salt in absence of air) with NaCl structure. 

Titanium II) oxide, TiO. Has the NaCl structure but is non-stoicheiomeiric (Ti02 plus Ti). 

The lanthanoids also form metal-rich carbides of stoichiometry M3C in which individual C atoms occupy at random one-third of the octahedral Cl sites in a NaCl-like structure. Several of the actinoids (e.g. Th, U, Pu) form monocarbides, MC, in which all the octahedral Cl sites in the NaCl structure are occupied and this stoichiometry is also observed for several other carbides of the early transition elements, e.g. M = Ti, Zr, Hf V, Nb, Ta Mo, W. These... 

Compounds with Sc, Y, lanthanoids and actinoids are of three types. Those with composition ME have the (6-coordinated) NaCl structure, whereas M3E4 (and sometimes M4E3) adopt the body-centred thorium phosphide structure (Th3P4) with 8-coordinated M, and ME2 are like ThAsi in which each Th has 9 As neighbours. Most of these compounds are metallic and those of uranium are magnetically ordered. Full details of the structures and properties of the several hundred other transition metal-Group 15 element compounds fall outside the scope of this treatment, but three particularly important structure types should be mentioned because of their widespread occurrence and relation to other structure types, namely C0AS3,... 

NaCl structure, superconductor below 3.5 K), SotAss (defect NaCl structure, superconductor below 1.2K). The many important industrial applications of dilute alloys of As, Sb and Bi with tin and lead were mentioned on pp. 370 and 371. 

Monochalcogenides, LnZ (Z = S, Se, Te), have been prepared for all the lanthanides except Pm, mostly by direct combination.They are almost black and, like the monoxides, have the NaCl structure. However, with the exceptions of SmZ, EuZ, YbZ, TmSe and TmTe, they have metallic conductivity and evidently consist of Ln -t- Z ions with 1 electron from each cation delocalized in a conduction band. EuZ and YbZ, by contrast, are semiconductors or insulators with genuinely divalent cations, but SmZ seem to be intermediate and may involve the equilibrium ... 

Turning next to an ionic crystal, where the ions may be regarded as spheres, the total volume of the crystal is equal to the volumes of these spheres, together with the appropriate amount of void space between the spheres. To take the simplest case, it is convenient to discuss a set of substances, all of which have the same crystalline structure—for example, the 17 alkali halide crystals that have the NaCl structure. 

The compound Li4Nb04F crystallizes in cubic syngony, with a cell parameter of 4.192 A and a Rock Salt (NaCl) structure. The compound s X-ray diffraction pattern and cell parameter are very similar to those of nickel oxide, NiO. 

As expected from the similarity of ionic radii between Ag+ (1.15 A) and Na+ (1.01 A), one form has the NaCl structure (it is trimorphic) with other forms having the CsCl and inverse NiAs structures. Unlike the other silver(I) halides, it is very soluble in water (up to 14 M) and forms di- and tetra-hydrates it is decomposed by UV rather than visible light and melts unchanged at 435°C. 

Most monochalcogenides of the Group 3 metals adopt the rock salt (NaCl) structure. Note that the crystal chemistry of divalent europium is very similar to that of the alkaline earths, particularly strontium, as the radius of Eu is almost the same as that of Sr ". For the Yb compounds, the cell dimensions are practically identical with those of the Ca compounds. 

The most prevalent modification of the disulfide, FeS2, is pyrite, which may be visualized as a distorted NaCl structure where the Fe atoms occupy sodium positions and S2 groups are placed with their centers at the chloride positions. Pyrite is a largely occurring crystal with semiconductor properties Eg = 0.95 eV). Another modification of FeS2 is the very similar to pyrite but somewhat less regular marcasite structure. 

TIO is cubic with the NaCl structure. A sample was annealed at 1300 °C. Density and X-ray measurements revealed that the intrinsic defects were Schottlqr in nature (Vxi + Vq) and that their concentration was 0.140. In... 

The structure of calcite (CaC03) can be derived from the NaCl structure by substituting the Cl- ions for CO2- ions. These are oriented perpendicular to one of the space diago-... 

Further examples where these rules are observed are as follows. Under pressure, some compounds with zinc blende structure, such as AlSb and GaSb, transform to modifications that correspond to the J3-Sn structure. Others, such as InAs, CdS, and CdSe, adopt the NaCl structure when compressed, and their atoms thus also attain coordination number 6. Graphite (c.n. 3, C-C distance 141.5 pm, density 2.26 gem-3) pr Te diamond (c.n. 4, C-C 154 pm, 3.51 gem-3). 

Whereas AgCl has the NaCl structure, Agl has the zinc blende structure. Could you imagine conditions under which both compounds would have the same structure ... 

The interstitial hydrides of transition metals differ from the salt-like hydrides of the alkali and alkaline-earth metals MH and MH2, as can be seen from their densities. While the latter have higher densities than the metals, the transition metal hydrides have expanded metal lattices. Furthermore, the transition metal hydrides exhibit metallic luster and are semiconducting. Alkali metal hydrides have NaCl structure MgH2 has rutile structure. 

Under pressure Agl could adopt the NaCl structure (it actually does). 

---