Acta Crystallographica Section A Foundations of Crystallography · 1995 · 20 citations · 0 references
Natural SciencesChemistryMaterials ScienceCrystal StructureInorganic ChemistrySolid-state ChemistryCrystal ChemistryCrystallographyPhase AnalysisStructure DeterminationX-ray CrystallographyX-ray DiffractionCrystal Chemistry Of SilicatesCrystal Structure DeterminationLayered MaterialsPowder DiffractionPowder Diffraction AnalysisPowder X-ray DiffractionSilicate Crystal StructuresZeolites
The viability of solving the structure type of zeolitic and layered materials applying multisolution direct methods to low-resolution (~2.2 Å) powder diffraction data is shown. The phases are refined with the tangent formula derived from Patterson-function arguments [Rius (1993). Acta Cryst. A49, 406–409] and the correct phase sets are discriminated with the conventional figures of merit. The two test examples presented are (a) the already known tetragonal zeolite ZSM-11 (space group 1{\bar 4}m2) at 2.3 Å resolution and (b) the hitherto unknown layer silicate RUB-15 (Ibam) at 2.2 Å resolution. In both cases, the tetrahedral Si units appear as resolved peaks in the Fourier maps computed with the phases of the highest-ranked direct-methods solutions.