Anion lattice

Therefore the relationship between these interconvertible structures originates from a cubic anion lattice of 32 0 ions in the cell. With 32 Fe ions in the octahedral holes stoichiometric FeO is formed. Replacement of a number of Fe ions with two-thirds of their number of Fe ions maintains electrical neutrality but provides non-stoichiometric Fei 0. Continual replacement in this way to leave 24 Fe atoms in the cubic cell produces Fej04, and... 

In actual oxidation, the cubic anion lattice becomes extended by the addition of new layers of close-packed 0 ions into which Fe atoms migrate to give rise to the appropriate stable structures. 

Tetrahedral and octahedral interstitial holes are formed by the vacancies left when anions pack in a ccp array, (a) Which hole can accommodate the larger ions (b) What is the size ratio of the largest metal cation that can occupy an octahedral hole to the largest that can occupy a tetrahedral hole while maintaining the close-packed nature of the anion lattice (c) If half the tetrahedral holes are occupied, what will be the empirical formula of the compound MVAV, where M represents the cations and A the anions ... 

Only recently [42a, 46, 47] it was found that the presence of an electron rich transition metal such as Ir in melts of BiX3 (X = Cl, Br) and Bi metal leads to the formation of large isolated and weakly coordinating cluster anions of type [IrBi Xn]-and [IrBi Xn]2- that stabilize the smaller hitherto unknown Bis+ and Bi 2+ in the interstices of the anion lattice (Eq. 5). 

Takimiya K, Kodani M, NiUiara N, Aso Y, Otsubo T, Bando Y, Kawamoto T, Mori T (2004) Pressure-induced superconductivity in (MDT-TS)(Aul2)o.44i [MDT-TS = 5H-2-(l,3-diselenol-2-ylidene)-l,3,4,6-tetrathiapentalene] anew organic superconductor possessing an incommensurate anion lattice. Chem Mater 16 5120-5123... 

Two possible space-based schemes are the random structure approach and the lattice method. In the first, the atoms are placed in random positions to form an initial structure containing no chemical information. The configuration of the atoms is then altered in such a way as to better match a pre-selected set of chemical or physical constraints. In the second approach the cations and anions are separately arranged on lattices that minimize the electrostatic repulsions between the (like) ions. The lattices are then merged by placing the anion lattice in the cavities of the cation lattice and vice versa. 

NH3 is similar to H2O in that they both possess large dipole moments and are both small molecules. The presence of NH3 in a zeolite is chemically similar to the presence of H2O in a zeolite. Therefore, the hydrated cation distribution in zeolites is probably more typical of NH3 adsorption in zeolites than the dehydrated cation distribution. According to Breck (18), for hydrated zeolite X, cations are found in sites SI, SI, SII, and SIV. Of these sites, SI, SII, and SIV would all be adsorption lattice solution sites. The cationic and anionic lattice solution sites (in the supercavity of NaX) are illustrated in Figure 8. For NH3, the subscript J1 will refer to SII sites, the subscript J2 will refer to SI sites, and J3 will refer to SIV sites. The anionic sites are two and are (l) in the center U-membered ring of the connecting frame and (2) near the center of the 0(2)—0(1)—0(l) triad of oxygen atoms. For NH3, the subscript il will refer to the first anionic site the subscript i2 will refer to the second anionic site. 

Fig. 6. Rotational cation-anion (lattice) vibration ofsymmetry...

Anion lattice The key to the simple description of ionic compounds. Often close-packed. Bond diagram The key to the simple description of covalent compounds. Often a fragment of a close-packed array 7>. 

W The regularity of the anion-lattice in the top structure of Fig. 10 does not quite correspond to a minimum in the system s potential energy. 

In perovskite (CaTiOs) and its isomorphs such as BaTiC>3, the large alkaline earth ions replace O2- ions in the anion lattice and the Ti4+ ions occupy all the octahedral interstices that are surrounded only by O2- ions, i.e. no Ti4+ ions are immediately adjacent to divalent cations. 

The monoclinic structure of M02S3 (142) [C h — P2i/m, all atoms in 2(e)] is based on a distorted close-packed anion lattice with layer sequence chh (Fig. 41). The cations are inserted in some of the octahedral holes. The... 

The sphalerite structure exhibits a unit cell with a ccp anion lattice with one type of tetrahedral hole occupied with cations. What is the compound stoichiometry ... 

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