An optical method of studying the diffraction from imperfect crystals III. Layer structures with stacking faults

Abstract
The reciprocal lattice intensity distribution has been determined quantitatively using a photomultiplier to measure the optical diffraction intensities. The systems examined included the simple-cubic structure with 'wollastonite-type’ stacking faults, the close-packed-hexagonal structure with growth faults, and the face-centred-cubic structure with de­formation faults on one set and on two sets of {111} planes. It is shown that the Paterson (1952) analysis of the diffraction from deformation faulted f. c. c. crystals can be extended to intersecting faulted {111} planes, provided that the faulting parameter, α , is not greater than about 0·1. The main limitation of the optical method concerns the restriction in the number of layers (10 3 ) which can be conveniently represented in one grating. This restriction gives rise to weak fluctuations in the observed intensity distribution and to an uncertainty of up to 0·03 in the determination of α from this distribution.
Keywords