Solid state NMR spectroscopy as supporting method in Rietveld structure refinements of rock-forming minerals: New developments and examples
Michael Fechtelkord, 2004. "Solid state NMR spectroscopy as supporting method in Rietveld structure refinements of rock-forming minerals: New developments and examples", Spectroscopic methods in mineralogy, Anton Beran, Eugen Libowitzky
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Over centuries mineralogy has developed from a mainly descriptive scientific discipline to a quantitative experimental research field covering a wide area. A broad spectrum of different mineralogical disciplines, ranging in their topics from the macroscopic physical and chemical properties of igneous rocks up to the atomic structures and characteristics of minerals, crystals and materials is applied today. Mineralogy can be regarded as a field of both Earth sciences and materials science and is an extraordinarily manifold scientific discipline with numerous points of contact to geology, chemistry, physics and materials science, characterised by the large variety of methods used in basic and applied research.
A wide variety of analytical methods such as diffraction methods, microscopy, thermal analysis and spectroscopy is used in the different research fields of mineralogy, each method contributing small pieces to the large puzzle of unsolved scientific questions. Often several methods fail in the investigation of structural aspects as in the case of amorphous materials (e.g. glasses from magmatic melts) or microcrystalline materials and for specific structural questions, e.g. the location and dynamics of hydrogen atoms in minerals. Solid state nuclear magnetic resonance can be an ideal complementary method here.
All nuclei that possess a magnetic moment (I > 0) are able to provide detailed information about their local environments as local probe, e.g. about bond angles, neighbouring atoms (1st and 2nd coordination sphere), local symmetry, the coordination number, as well as being sensitive to dynamic processes (Chandrakumar & Subramanian, 1987; Ernst et al., 1987; Fyfe, 1983; Slichter, 1990).
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Spectroscopic methods provide information about the local structure of minerals. The methods do not depend on long-range periodicity or crystallinity. The geometric arrangement of atoms in a mineral phase is only one aspect of its constitution. Its vibrational characteristic, electronic structure and magnetic properties are of greatest importance when we consider the behaviour of minerals in dynamic processes. The characterisation of the structural and physico-chemical properties of a mineral requires the application of several complementary spectroscopic techniques. However, it is one of the main aims of this School to demonstrate that different spectroscopic methods work on the same basic principles. Spectroscopic techniques represent an extremely rapidly evolving area of mineralogy and many recent research efforts are similar to those in materials science, solid state physics and chemistry. Applications to different materials of geoscientific relevance have expanded by the development of microspectroscopic techniques and by in situ measurements at low- to high-temperature and high-pressure conditions.