C-face-centred

Fig. 3.8 Some basic Bravais lattices (a) simple cubic, (b) body-centred cubic, (c) face-centred cubic and (d) simple hexagonal close-packed. (Figure adapted in part from Ashcroft N V and Mermin N D 1976. Solid State Physics.

Fig 2. The 14 three-dimensional translation lattice types (Bravais, 1850). P = primitive C = c-face centred, F = all face centred, R = rhombohedral (crystals In the 7 rhombohedral space groups are described in relation to hexagonal axes). 

There are only 14 possible three-dimensional lattices, called Bravais lattices (Figure 5.1). Bravais lattices are sometimes called direct lattices. The smallest unit cell possible for any of the lattices, the one that contains just one lattice point, is called the primitive unit cell. A primitive unit cell, usually drawn with a lattice point at each comer, is labelled P. All other lattice unit cells contain more than one lattice point. A unit cell with a lattice point at each corner and one at the centre of the unit cell (thus containing two lattice points in total) is called a body-centred unit cell, and labelled I. A unit cell with a lattice point in the middle of each face, thus containing four lattice points, is called a face-centred unit cell, and labelled F. A unit cell that has just one of the faces of the unit cell centred, thus containing two lattice points, is labelled A-face-centred if the faces cut the a axis, B-face-centred if the faces cut the b axis and C-face-centred if the faces cut the c axis. 

Figure 1.15. The three cubic lattices a) cube b) body-centred cube (c) face-centred cube...

An upper-case letter denoting the lattice type P = primitive I = body-centred F = face-centred (full) C = face-centred (side) R = rhombohedraL... 

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