Strukturbericht and Pearson Notation

The structures of intermetallic phases are often designated in the literature by Strukturbericht and Pearson symbols instead of by the space group. The Strukturbericht method for classifying metallic structures consists of a capital letter followed by a number and a subscript. The A-series were supposed to be elemental structures (with an exception for A-15) the B-series, AB compounds the C-series, AB2 compounds, etc. The number and subscript following the letter designated the lattice. Examples are A1 for fee, A2 for bcc, Aa for bet, A3 for hep, A4 for diamond, etc., up to A20. For the AB binary systems, B1 is the NaCl structure, B2 is the CsCl structure, B3 is zinc blende, B4 is wurtzite, etc. up to B37. C designates the AB2 compoimds, D the A Bm compounds, etc. 

Pearson symbols are also used to indicate the crystal symmetry and the number of atoms in the imit cell. The Bravais lattice is designated by a lower case letter indicating the basic crystal class (c-cubic, h-hexagonal or trigonal, t-tetragonal, o-orthorhombic, m-monoclinic, and a-asymmetric [triclinic]), followed by B, F, 1, or P to indicate symmetry of the lattice, and then the number of atoms in the unit cell. For example, NaCl would be designated cF8, Fe would be cI2, perovskite would be cP5, Hg2Cl2 would be tI8, etc. 

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Introduces point and space groups as well as Strukturbericht and Pearson notation... 

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