NOVEL APPROACHES TO HIGH-PRESSURE CRYSTALLOGRAPHY WITH GEOLOGICAL APPLICATIONS

Polychromatic radiation has been used in high pressure x-ray diffraction studies for almost two decades, but has never been demonstrated to be competitive with monochromatic experiments in terms of applicability of it's results in full structure determination. This presentation will summarize the current status of new, major collaborative development project located at three high-pressure synchrotron beamlines in USA. It will be shown that by combining the experience and ideas from such fields as high-pressure crystallography, protein Laue crystallography, microdiffraction, and EXAFS, new crystallographic methods, offering unique advantages and optimized for mineral physics, petrology, and paleontology applications can be developed. Examples of pilot studies focused on inter-polytypic phase transitions in sedimentary minerals will be presented. The results of single-crystal XRD studies with kaolin minerals will be discussed in the context of recent first-principles calculations and their possible relevance in triggering deep-focus earthquakes.