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Crystal chemistry of minerals

English title Crystal chemistry of minerals
Applicant Armbruster Thomas
Number 122122
Funding scheme Project funding (Div. I-III)
Research institution Institut für Geologie Universität Bern
Institution of higher education University of Berne - BE
Main discipline Mineralogy
Start/End 01.12.2008 - 31.01.2011
Approved amount 203'621.00
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Keywords (10)

crystal structure; minerals; zeolites; cation exchange; crystal chemistry; X-ray diffraction; ceramic materials; dehdration; geomaterials; properties

Lay Summary (English)

Lead
Lay summary
Short abstractThe crystal structures of selected crystalline materials, analogues of minerals, are studied by single crystal X-ray diffraction at various temperatures to understand the structural and chemical origin of their physical properties.BackgroudMinerals are naturally occurring, crystalline, inorganic compounds and many have interesting properties, be they physical, electronic, optical or magnetic, with important impact on our society and daily life. The current research project exploits use of minerals or inorganic compounds with mineral structures for potential environmental and technological applications. In the foreground of the project is the characterization of minerals, or their synthetic analogues, with respect to chemical, physical and structural properties. Scientific frame and experimental methodsOn order to explore the atomic structure of a crystalline solid, we use crystals < 0.1 mm for X-ray diffraction experiments. The most important experimental tool in our research is single-crystal X-ray structure analysis at different temperature (between 100 and 900 K), highlighting thermal expansion and its structural reason, dehydration of minerals associated with structural distortion and diffusion, and anisotropy of atomic vibrations. Three mineral groups are investigated: zeolites, mullite-like compounds, and garnets.Investigated MaterialsIsostructural heulandite and clinoptilolite are important natural aluminosilicate zeolites used as ion-exchanger, mainly to concentrate NH4, Pb2+, Cd2+ and Cs, Sr radioisotopes (from nuclear reactions) in their structural channel system. We investigate thermal stability, dehydration, ionic diffusion and structural distortion of exchanged zeolites in order to understand their behaviour at elevated temperature. Mullite-related structures are important ceramic materials due to their excellent thermal properties like thermal shock resistance and high temperature shape stability. Inspired by a new mineral recently discovered by us, we will synthesize small single-crystals of mullite related compounds in the ternary system B2O3-Al2O3-SiO2. Thermal expansion and structural distortion will be measured for different stoichiometries.Garnets are cubic minerals and their synthetic counterparts have various applications in laser technology and most recently also in rechargeable Li-batteries. Cation excess garnets of Li5La3M2O12 (M =Ta, Nb, Zr) composition exhibit Li conductivity. We study temperature dependence of anisotropic ionic vibration in cryolithionite Li3Al2Na3F12 as a model for Li-bearing garnets.
Direct link to Lay Summary Last update: 21.02.2013

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Associated projects

Number Title Start Funding scheme
127961 Alkaline and alkaline-earth alumosilicate materials as perspective ceramic materials for industrial applications 01.12.2009 SCOPES
112198 Crystal chemistry of minerals 01.06.2006 Project funding (Div. I-III)
134617 Crystal Chemistry of Minerals 01.05.2011 Project funding (Div. I-III)

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