Octahedral interspace

There are two types of interspace present amongst the cube Octahedral interspace (B site) and tetrahedral interspace (A site), as shown in Fig. 3.62. The 32 of oxygen ions constitute the interspace of both 64 tetrahedrons and 32 octahedrons. In a crystal of Fe304, eight Fe + and eight Fe + ions occupy the octahedral interspace, while the another eight Fe + ions occupy the tetrahedral interspace, namely, Fe3+ (Fe2+ Fe3+) O4. 

As previously described, FeO is an oxygen excessive (Fe defect) non-stoichiometric iron oxide (Fei xO), which shows the rock-salt type face center cubic structure (fee). The unit cell of Fei xO are constituted from four Fei xO molecules, where there are eight tetrahedral interspaces A site) and four octahedral interspaces B sites) with 0 closely packing onto NaCl-type cubic lattices. 

Nevertheless, in the structure of wiistite, for the reason of Fe + cations being defective, there still exist given amount of Fe + cations besides Fe + cations in order to preserve electric charge neutrality. These Fe + cations enter generally into the original empty interspace of tetrahedron. At the same time, if one of the vacancies of Fe + is formed in the lattice, then in order to maintain the electric charge neutrality, there must be two of Fe + transferring to be two of Fe +, one of which will enter into the tetrahedron interspace and leave behind an empty space in the octahedral interspace, while the another Fe + stays in octahedral interspace. For example, when X = 0.10 in Fei xO, then the structural formula can be written as ... 

In Scheme 1, octahedral coordination of central metals may lead to a three-dimensional polymer (22). In order to prevent the formation of this polymer and to prepare selectively a linear polymer, a special area for the reaction, such as the interspace of layer compounds or an organic monolayer film, is used. Kanda et al.19) synthesized the polymer in the organic monolayer film prepared by spreading a ligand solution on the surface of an aqueous solution containing metal ions. 

The prism caps of Pb coordination prisms are fairly well commensurable with the dimensions of square pyramids of As, Sb and Bi, the latter (or the groups BSg) are in turn commensurable with the coordination octahedra around Pb, Mn, In, Fe, Ag, (Hg), etc., or with tetrahedral and trigonal coordinations of primarily Ag and Cu. The latter may fill interspaces in the above arrays or form polyhedral arrangements of their own, with only subdued amounts of prismatic, pyramidal or octahedral cations present. 

Higher homologues start at N = 4 they allow more pronounced departures from the galena-like array, especially in the form of locally "inflated interspaces that accommodate lone electron pairs of quasi-octahedral Bi or Sb (so-called lone electron pair micelles, Makovicky Mumme, 1983). Onjy and are known for the Ag-free subsystem Pb-Bi-S. Reduction of symmetry in from the usual orthorhombic to monoclinic, caused by Pb/Bi ordering that proceeded differently for the two (originally) mirror-related slabs was exceptionally observed in one natural occurrence of (Mumme, unpubl.). Allowing for the Ag+Bi = 2Pb substitution in octahedral layers, also the cases L, and... 

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