Simulation of electron diffraction patterns from partially ordered layer lattices

• Published in: Ultramicroscopy Vol. 52; no. 3; pp. 512 - 522
• Main Authors: Treacy, M.M.J., Newsam, J.M., Deem, M.W.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Amsterdam Elsevier B.V 1993; Elsevier Science
• Subjects: Condensed matter: structure, mechanical and thermal properties; Defects and impurities in crystals; microstructure; Electron diffraction and scattering; Exact sciences and technology; Physics; Stacking faults and other planar or extended defects; Structure of solids and liquids; crystallography; Theories of diffraction and scattering; Stacking faults; Inorganic compounds; Algorithms; Electron diffraction; Selective area; Theoretical study; Diffraction pattern; Plane defects; Computerized simulation; Silicates; Zeolites; Recursion relations
• ISSN: 0304-3991; 1879-2723
• DOI: 10.1016/0304-3991(93)90068-9

By extending the theoretical treatments of Cowley and Hendricks and Teller, we have shown that the diffracted wave functions from successive slabs in crystals containing planar defects are related by simple recurrence equations. Recurrence equations greatly simplify the simulation of diffraction from coherently faulted crystals. Selected-area electron diffraction patterns for zeolite beta are simulated and compared with experimental data. Results are consistent with previous observations, made by structure imaging and powder X-ray diffraction, that zeolite beta is a highly disordered intergrowth of two unfaulted end-member structures, with a probability of a stacking fault being close to 50%. The quantitative accuracy of the recursion model of electron diffraction is limited by dynamical scattering effects.