Diffraction studies at extreme pressure-temperature conditions encounter intrinsic difficulties due to the small access angle of the diamond anvil cell and the high background of the diffraction peaks. Energy-dispersive x-ray diffraction is ideal for overcoming these difficulties and allows the collection and display of diffracted signals on the order of seconds, but is limited to one-dimensional information. Materials at high pressures in diamond anvil cells, particularly during simultaneous laser heating to temperatures greater than 3000 K often form coarse crystals and develop preferred orientation, and thus require information in a second dimension for complete analysis. We have developed and applied a diamond cell rotation method for in situ energy-dispersive x-ray diffraction at high pressures and temperatures in solving this problem. With this method, we can record the x-ray diffraction as a function of χ angle over 360°, and we can acquire sufficient information for the determination of high P-T phase diagrams, structural properties, and equations of state. Technical details are presented along with experimental results for iron and boron.
|Number of pages||4|
|Journal||Review of Scientific Instruments|
|State||Published - Feb 2001|
|Event||Advances in Laser Heated Diamond Cell Techniques - Chicago, IL, United States|
Duration: May 25 2000 → May 27 2000