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Rational synthesis and structure of a borosilicate zeolite with intersecting 10- and 11-ring channels
Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
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(English)Manuscript (preprint) (Other academic)
National Category
Inorganic Chemistry
Identifiers
URN: urn:nbn:se:su:diva-95867OAI: oai:DiVA.org:su-95867DiVA: diva2:661965
Available from: 2013-11-05 Created: 2013-11-05 Last updated: 2014-11-10
In thesis
1. Structural study of zeolites utilizing novel electron crystallographic methods: A voyage into the world of zeolite structures
Open this publication in new window or tab >>Structural study of zeolites utilizing novel electron crystallographic methods: A voyage into the world of zeolite structures
2013 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Electron crystallography has evolved as a powerful method for structural characterization of a wide range of materials. It has two significant advantages over other methods for structure determination, e.g. X-ray diffraction. Electrons interact much more strongly with matter compared to X-rays and they can be focused by electromagnetic lenses to form images with atomic resolution. These advantages make electron crystallography a unique tool for characterization of crystalline materials suffering from small crystal size and complex or disordered structures.

     Zeolites are a class of microporous materials with significance in several applications. They often possess complex and disordered structures, which demand large efforts in the structure determination.

     Over the last years, two new electron crystallographic methods have been developed; the rotation electron diffraction (RED) and the structure projection reconstruction from a through-focus series of high resolution transmission electron microscopy (HRTEM) images. In this thesis, they will be applied for structure determination of four new zeolite structures, including EMM-25 and EMM-23 with two ordered structures, and ITQ-39 and ITQ-38 with disordered structures. Each of the structure solutions have different challenges to overcome. The high silica borosilicate EMM-25 was solved by the RED method. The aluminosilicate EMM-23 was solved by a combination of HRTEM and RED. The structure solution of two materials with disordered structures, ITQ-39 and ITQ-38, will be described. For materials containing disorders, structure projection images are of utmost importance.

     Furthermore, the mesoporosity inside hierarchically porous ZSM-5 crystals was studied by a combination of focused ion beam (FIB) and HRTEM imaging. The last part of this thesis explores STEM imaging for use in structure determination from 3D reconstruction.

Place, publisher, year, edition, pages
Stockholm: Department of Materials and Environmental Chemistry (MMK), Stockholm University, 2013. 104 p.
Keyword
Electron crystallography, zeolites, structure determination, disorder, electron microscopy
National Category
Inorganic Chemistry
Research subject
Structural Chemistry
Identifiers
urn:nbn:se:su:diva-95870 (URN)978-91-7447-810-5 (ISBN)
Public defence
2013-12-16, Nordenskiöldsalen, Geovetenskapens hus, Svante Arrhenius väg 12, Stockholm, 10:00 (English)
Opponent
Supervisors
Note

At the time of the doctoral defence the following papers were unpublished and had a status as follows: Papers 4 and 5: Manuscipts; Paper 10: Manuscript

Available from: 2013-11-24 Created: 2013-11-05 Last updated: 2013-11-26Bibliographically approved
2. Characterization of crystalline materials by rotation electron diffraction: Phase identification and structure determination
Open this publication in new window or tab >>Characterization of crystalline materials by rotation electron diffraction: Phase identification and structure determination
2014 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Electron crystallography is powerful for determination of complex structures. The newly-developed 3D electron diffraction (ED) methods make structure determination from nano- and micron-sized crystals much easier than using other methods, for example X-ray diffraction. Almost complete 3D ED data can be collected easily and fast from crystals at any arbitrary orientations. Dynamical effects are largely reduced compared to zonal ED patterns. 3D ED is powerful for phase identification and structure solution from individual nano- and micron-sized crystals, while powder X-ray diffraction (PXRD) provides information from all phases present in the samples. 3D ED methods and PXRD are complementary and their combinations are promising for studying multiphasic samples and complicated crystal structures.

In this thesis, the feasibility and capability of 3D ED methods, specifically rotation electron diffraction (RED), in phase identification and structure determination of different kinds of crystalline materials with nano- or submicrometer-sized crystals are investigated. Experimental conditions for RED data collection and data processing in relation to data quality, as well as the challenges in the applications of RED are discussed.

RED was combined with PXRD to identify phases from as-synthesized samples and to characterize atomic structures of eleven crystalline compounds. It was shown to be possible to identify as many as four distinct compounds within one sample containing submicron-sized crystals in a Ni-Se-O-Cl system. RED was also used to determine unit cell and symmetry of isoreticular metal-organic frameworks (SUMOF-7) and solve five zeolite structures with new frameworks, ITQ-51, ITQ-53, ITQ-54, EMM-23 and EMM-25 and that of a metal-organic framework (MOF), SUMOF-7I. The structure of an open-framework germanate SU-77 was solved by combining RED with PXRD. The structures of the zeolites and SU-77 were confirmed by Rietveld refinement against PXRD. High-resolution transmission electron microscopy was used to confirm the structure models of ITQ-51, EMM-25 and SUMOF-7I.

Place, publisher, year, edition, pages
Stockholm: Department of Materials and Environmental Chemistry (MMK), Stockholm University, 2014. 102 p.
Keyword
electron microscopy, phase identification, rotation electron diffraction, structure determination, three-dimensional electron diffraction
National Category
Inorganic Chemistry
Research subject
Inorganic Chemistry
Identifiers
urn:nbn:se:su:diva-108930 (URN)978-91-7649-017-4 (ISBN)
Public defence
2014-12-17, Magnélisalen, Kemiska övningslaboratoriet, Svante Arrhenius väg 16 B, Stockholm, 10:00 (English)
Opponent
Supervisors
Note

At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 2: Submitted. Paper 4: Accepted. Paper 6: Manuscript. Paper 7: Epub ahead of print. Paper 9: Manuscript. Paper 11: Manuscript.

Available from: 2014-11-25 Created: 2014-11-06 Last updated: 2015-10-27Bibliographically approved

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