Tables for
Volume C
Mathematical, physical and chemical tables
Edited by E. Prince

International Tables for Crystallography (2006). Vol. C, ch. 9.3, p. 777

Section 9.3.1. Glossary

J. L. C. Daams,a J. R. Rodgersb and P. Villarsc

aMaterials Analysis Department, Philips Research Laboratories, Prof. Holstaan 4, 5656 AA Eindhoven, The Netherlands,bNational Research Council of Canada, Canada Institute for Scientific and Technical Information, Ottawa, Canada K1A 0S2, and cIntermetallic Phases Databank, Postal Box 1, CH-6354 Vitznau, Switzerland

9.3.1. Glossary

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Intermetallic compound: Intermetallic compounds are binary, ternary, quaternary, etc. compounds containing the chemical elements other than oxygen, the halides, and the noble gases. Also excluded are compounds containing typical inorganic groups like –NH, –NH2, –N2, etc. This definition was used for Pearson's Handbook (Villars & Calvert, 1991[link]), the Atlas of Crystal Structure Types (Daams, Villars & van Vucht, 1991[link]) and the CRYSTMET database (Rodgers & Villars, 1988[link]). This definition therefore also includes sulfides, selenides, carbides, and nitrides, which most material scientists would not consider to be intermetallic compounds, but, because of their structural similarity, they have been included.

Structure type (or prototype): Based on space-group theory, a crystal structure is completely determined by the following data:

  • chemical formula;

  • crystal system and unit-cell dimension(s);

  • space group;

  • occupation number and coordination of the occupied point sets.

Crystal structure types are named by the first intermetallic compound found to be unique in respect of the third and fourth items and are represented by the Pearson symbol followed by the formula of the prototype, e.g. hP3 AlB2. The first two letters of the Pearson symbol are identical to the Bravais-lattice type, and the digits give the number of atoms per unit cell.


Daams, J. L. C., Villars, P. & van Vucht, J. H. N. (1991). Atlas of crystal structure types for intermetallic phases. Materials Park, OH: ASM International.
Rodgers, J. R. & Villars, P. (1988). Computer evaluation of crystallographic data. In Proceedings of the 11th International CODATA Conference, Karlsruhe, FRG, edited by P. S. Glaeser. New York: Hemisphere Publishing Corp.
Villars, P. & Calvert, L. D. (1991). Pearson's handbook of crystallographic data for intermetallic phases, 2nd ed. Materials Park, OH: ASM International.

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