The body-centred cubic packing

The simple hexagonal sphere packing (c.n. 8), Fig. 4.1(b), is not of great importance as a crystal structure it is mentioned again later. A more dense arrangement with the same c.n. is the body-centred cubic packing illustrated in Fig. 4.1(c). Spheres are placed at the+iody-centre and corners of the cubic unit cell, and 

(a) Body-ccntrcd cubic packing viewed along face-diagonal, (b) Projection of face- 

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