Dynamic Powder Crystallography With Synchrotron X-Ray Sources

The increased brightness, tunability, low divergence and low emittance of X-ray beams available at synchrotron X-ray sources facilitate a variety of powder-diffraction experiments not practical using conventional in-house sources. Furthermore, the in-creased availability of fast position-sensitive detectors, along with implementation of improved software, make possible new classes of experiments. These include time-resolved powder-diffraction of phase transitions, precipitation, recrystallization and ion-exchange reactions. Examples of time-resolved studies that highlight some of these developments include: (1) observations of the phases forming during reaction under controlled hydrothermal conditions (e.g., FeS); (2) full Rietveld structure refinement using time-resolved data to determine the mechanism of ion exchange in zeolites. The advent of area detectors, commonly coupled with focusing optics at synchrotrons, will further increase the time resolution at the synchrotron, possibly leading to a data glut. Solutions are available now, and developments in the near term will allow semi-automatic decisions on which datasets to analyze amongst the thousands collected.