Correction of diffraction optics and P-V-T determination using thermoelastic equations of state of multiple phases

This report discusses a new method to determine experimental pressure-volum e-temperature (P-V-T) data and to correct misalignment of diffraction optic s using thermoelastic equations of state of multiple phases. Analytical app roaches as well as numerical approaches are presented for the technique. A number of phase combinations yield the best experimental result and the who le-pattern Rietveld and/or Le Bail refinement of diffraction patterns of mu ltiple phases is a significant aspect of the technique. Specific examples i ndicate that the corrected pressure, temperature and diffraction optics are robust. Errors are estimated from the uncertainties of the measured cell d imensions. The error propagation for different experimental cases is discus sed, along with the conditions and limitations of the method. This techniqu e for P-V-T determination and the correction of diffraction optics is cruci al for experiments conducted under extreme conditions of high pressure, hig h temperature and dynamic reactions.