New HPCAT Laue micro-diffraction setup at APS 16-BM-B beamline

New HPCAT Laue micro-diffraction setup at APS 16-BM-B beamline

White beam Laue diffraction is widely used to study materials, nevertheless applications of Laue techniques to high pressure area has been very limited so far due to experimental challenges. It was recently demonstrated [1] that Laue diffraction can be a very powerful tool for real time microstructural studies at high pressures due to fast data collection. Therefore recently we have built and commissioned a new white beam Laue micro-diffraction setup optimized for high pressure studies (Fig. 1). The new setup allows studying crystal morphology, local texture, twinning, orientation relations between inter grown crystals, lattice rotation, deviatoric strain, defects in real time mode with second level time resolution. The major areas of application of the new setup include studies of mechanisms of pressure induced phase transitions, melting and crystallization under high pressure, deformation under hydrostatic and non-hydrostatic stress. The large X-ray energy range, from 5 to about 70keV, allows conducting efficient Laue measurements in diamond anvil cells. Perkin Elmer area detector with readout time of only 0.13 sec and high sensitivity to high energy X-rays is used to record diffraction patterns. X-ray beam is focused down to 2.3×2.3mm2 at sample position with KB-mirrors. The setup is based on granite table providing high mechanical stability. Fast XY-stages from Newport and fast elevation stage from Aerotech are used for dynamic sample positioning. Typically sets of 2D translational scans are collected across the sample while pressure or non-hydrostatic stress is increasing thus providing both spatially and time resolved microstructural information simultaneously.

Fig. 1. HPCAT Laue micro-diffraction setup at 16-BM-B beamline.

 

References

1.       D. Popov, C. Park, C. Kenney-Benson, G. Shen High pressure Laue diffraction and its application to study microstructural changes during the α→βphase transition in Si. Review of Scientific Instruments, 2015, 86, 072204