Buchsteiner, Emilia (2024)
Three-dimensional Electron Diffraction for Crystal Structure Solution of Complex Natural Silicates.
Technische Universität Darmstadt
doi: 10.26083/tuprints-00028913
Dissertation, Erstveröffentlichung, Verlagsversion

Kurzbeschreibung (Abstract)

The characterization and hence the understanding of complex silicates pose a significant challenge due to their intricate structures and diverse chemical compositions. Conventional crystallographic techniques often fall short in providing comprehensive and accurate crystal structure information for these structures. However, recent advances in electron diffraction techniques offer promising avenues for overcoming these limitations. This thesis explores the application of three-dimensional electron diffraction (3D ED) as a powerful tool for solving the crystal structures of complex natural silicates. Three minerals were chosen for their exceptional and challenging structural characteristics, which have previously complicated or even hindered successful structure determination through conventional methods such as X-ray powder diffraction (XRPD). In the first part of the study, a structure solution on a single crystal of illite is demonstrated, where prior attempts using XRPD failed due to inherent limitations in dealing with its impurity and disorder. Additionally, a new form of disorder is identified and characterized, providing valuable insights into fluid-dependent structure alterations and rendering a new model for XRPD data refinement. With labradorite, the research showcases 3D ED's ability to handle materials with incommensurate modulations and low symmetry, offering a possibility for direct comparison of data taken from different length scales. Moreover, a complete hierarchical structure description is provided. Finally, the structure of one of the most intricate minerals known, eveslogite, is solved despite its twinning on a nanoscale demonstrating the advantage of an accessibility to single crystalline nano domains. Throughout this thesis, the advantages of 3D ED as a promising alternative to traditional methods are highlighted, especially in dealing with complex silicate minerals. The successes achieved in unraveling the atomic structures of illite, labradorite and eveslogite, which constitutes the largest mineral structure ever solved by 3D ED methods, demonstrate the power and versatility of 3D ED as a cutting-edge technique for structure analysis in the realm of mineralogical research. These findings pave the way for further advancements and open new avenues in the field of crystallography.

Frage zum Eintrag

Redaktionelle Details anzeigen