On the diffraction of X-rays by face-centred cubic crystals containing extrinsic stacking faults

A solution is given to that problem of extrinsic faulting in face-centred cubic crystals in which additional layers may be inserted with equal probability after layers of original crystal or after previously inserted layers. The method employed involves the derivation and solution of an appropriate difference equation. The distribution of diffracted intensity differs from that given previously [Sabine, Acta Cryst. (1966), 21, 882-884], but it does show expected behaviour both for small values of the fault probability and for values near unity.