International
Tables for Crystallography Volume A Space-group symmetry Edited by Th. Hahn © International Union of Crystallography 2006 |
International Tables for Crystallography (2006). Vol. A. ch. 5.1, p. 84
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Figure 5.1.3.6
Unit cells in the rhombohedral lattice: same origin for all cells. The basis of the rhombohedral cell is labelled a, b, c. Two settings of the triple hexagonal cell are possible with respect to a primitive rhombohedral cell: The obverse setting with the lattice points 0, 0, 0; ; has been used in International Tables since 1952. Its general reflection condition is . The reverse setting with lattice points 0, 0, 0; ; was used in the 1935 edition. Its general reflection condition is . (a) Obverse setting of triple hexagonal cell in relation to the primitive rhombohedral cell a, b, c. (b) Reverse setting of triple hexagonal cell in relation to the primitive rhombohedral cell a, b, c.(c) Primitive rhombohedral cell (- - - lower edges), a, b, c in relation to the three triple hexagonal cells in obverse setting ; ;. Projection along c′. (d) Primitive rhombohedral cell (- - - lower edges), a, b, c in relation to the three triple hexagonal cells in reverse setting ; ; . Projection along c′. |