Nomenclature of inorganic structure types. Report of the International Union of Crystallography Commission on Crystallographic Nomenclature Subcommittee on the Nomenclature of Inorganic Structure Types

Abstract

Different degrees of similarity between inorganic crystal structures are defined concisely and examples are presented that illustrate their practical application. A notation giving the coordination of atoms is presented together with some basic rules for developing crystal-chemical formulae and the Bauverband description of inorganic structure types. Typical examples of the nomenclature are: pyrite Fe[6°]{g}[S2 (3;1)t ], [F(□2l) + F′FeS2Pa\bar 3; spinel Mg[4]AI2 [6]O4, ∞ 3[Mg[4t]lAl2 [6o]O4 [l,3;12co]], Fm 222 + D, T′ MgAI2O4 Fd\bar 3m.

High‐Temperature Experimental and Theoretical Study of Magnetic Interactions in Diamond and Pseudo‐Diamond Frameworks Built up from Hexanuclear Tantalum Clusters

“…[6] The intrinsic absorption, transport and magnetic properties of metal-atom cluster compounds are related to the strength of the interaction between cluster units and to the number of metallic electrons (ME), that is, electrons that are available for metal-metal bonding within the cluster. In the approximation of O h symmetry, the molecular orbital (MO) diagram shows a set of eight metal-metal-bonding molecular orbitals (a 1g , t 1u , t 2g and a 2u ) for the [M 6 L i 12 L a 6 ] unit, which leads to a closed-shell configuration with an ME count of 16. It was found experimentally that the number of ME can range from 14 to 16 electrons per cluster.…”

Toward a comprehensive definition of oxidation state (IUPAC Technical Report)

“…A crystal-chemical formula [53] lists each crystallographically nonequivalent atom in the structure and contains information about that atom's coordination to other atoms in superscripted square brackets. The coordination numbers in the brackets follow the same array order as the atoms in the formula and are separated by a comma while eventual bonding to atoms of the same element comes after a semicolon.…”

Integration of first-principles methods and crystallographic database searches for new ferroelectrics: Strategies and explorations

“…At the other extreme, there are 13 space groups in which all entries have no reported structure type: 183, 172, 171, 168, 158, 106, 105, 101, 80, 78, 37, 35 and 3; however the total number of entries in these groups is only 196, or 1.6% of the total number of all polar entries. While a systematic classification system for the assignment of inorganic structure type has been established [54], it seems that these conventions are not always followed in the literature, and thus not in the ICSD. The case of tetragonal space group 99 illustrates the problem of structure type nomenclature: the similarity of the PbTiO 3 and KNbO 3 structures suggests that, following the guidelines of Ref.…”

“…The case of tetragonal space group 99 illustrates the problem of structure type nomenclature: the similarity of the PbTiO 3 and KNbO 3 structures suggests that, following the guidelines of Ref. [54], these should be combined and regarded as a single structure type. An automated classification method based on the structural information in ICSD would reduce or even eliminate such problems, and could also assign missing structure types, especially in cases where the system is chemically different from other representatives and the structural relationship was not recognized by the authors of the original paper.…”