A careful analysis of X-ray powder diffraction lines of this Aurivillius compound showed that stacking faults were located along the c-axis, and that the (hk0) reflections were therefore unaffected by faulting. In the [00l] direction, the profiles exhibited a Lorentzian shape and a 22nm coherently diffracting domain size was found which corresponded to a stacking-fault density of 0.032/nm. The reciprocal-space mapping technique, as applied to epitaxial layers, permitted direct visualization of the highly anisotropic (00l) reciprocal-lattice points. Because of high counting rates and a lack of peak overlap in epitaxial layers, very subtle changes in the diffraction profiles could be monitored as a function of heat-treatment time. Annealing (700C, up to 600h) reduced the stacking-fault density, as reflected by a marked increase in the domain size (198nm) and broadening of the domain size distribution. A significant lowering of the Lorentzian character of the diffraction profiles was also found; in perfect accord with the stacking-fault density reduction.

Planar Faults in Aurivillius Compounds - an X-Ray Diffraction Study. A.Boulle, C.Legrand, R.Guinebretiè, J.P.Mercurio, A.Dauger; Philosophical Magazine A, 2002, 82[3], 615-32