Effect of Intergrowth Defects on the X-Ray Diffraction Pattern. I. Structure Simulations

The presence of intergrowth with a different spacing inside a layered phase causes significant alterations in the X-ray diffraction pattern, concerning both line positions and widths. An analysis of these changes, based on a Hendricks-Teller-type formalism yields estimates about the defect nature, concentration and short-range order. The procedure was exemplified by simulation of XRD patterns for Bi-based oxidic superconductors, in which intergrowths of related phases are often present inside the matrix phase. La presence des defauts d'intercroissance dans une phase lamellaire cause des changements du spectre de diffraction des rayons X. Ces changements concernent la position, aussi bien que la largeur des raies. L'analyse de ces alterations, en employant le formalisme Hendricks-Teller peut nous informer sur la nature des defauts, leur concentration et l'ordre a courte distance. Le procede est illustre en simulant des spectres de diffraction pour les oxides BiSrCaCuO, ou l'intercroissance des phases apparentees se produit frequemment.