Micro-focused white beam Laue diffraction at HPCAT

Laue diffraction setup optimized for microstructural studies at high pressure is available for users at 16BMB beamline of the Advanced Photon Source.

Due to fast data collection, Laue diffraction is a powerful tool for real time microstructural measurements. Despite white beam diffraction being widely implemented, applications of this approach to high pressure area so far are very limited. This is the reason why HPCAT Laue diffraction setup is specifically optimized for high pressure studies.

Some examples of research areas using the new Laue setup include: elastic and plastic deformation under hydrostatic or non-hydrostatic stress, orientation relations between inter-grown crystals, pressure induced phase transitions, melting and crystallization under high pressure, strength of materials at high pressures.

The following information is available in real-time mode in a matter of seconds:

  • Crystal morphology
  • Local texture
  • Twinning
  • Orientation relations between inter grown crystals
  • Lattice rotation
  • Deviatoric strain
  • Defects

Efficient measurements in diamond anvil cells (DAC)

  • Large X-ray energy range: 5 to 70keV
  • Membrane system or gearbox are available to change pressure remotely
  • Off-line Ruby system is available inside the hutch to measure DAC pressure
  • Reflections from diamonds are blocked by detector mask to prevent the detector from damage

High mechanical stability: based on Granite table

Perkin Elmer area detector

  • Short readout time of 0.13sec
  • Efficient for high X-ray energies

Flexible geometry

  • Orientation of area detector with respect to X-ray beam can be changed from 0 to 90°in vertical plane in step of 15°
  • Sample to detector distance can be changed from 300 to 600mm in step of 50mm
  • Two area detectors, one in transmitted and one in 90°geometry, can be used simultaneously

Focusing system based on KB-mirrors

  • X-ray beam can be focused by KB-mirrors down to 2.3×2.3 µm2
  • Highest X-ray energy limit is adjustable by tilt of the mirrors
  • X-ray beam spot size is adjustable

Sample mount: fast XY-table from Newport is mounted on top of Newport’s rotational stage which in turn is mounted on top of fast elevation stage from Aerotech.

Typical cycle of data collection

  • Series of 2D translational scans are collected across the sample one scan after another while pressure or non-hydrostatic stress is increasing
  • Automatic increase of membrane pressure using soft IOC
  • ImageJ is used for real time observations

Si111 channel cut monochromator provides monochromatic beam switchable with white beam

 

Publications

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

2.R. Barabash, O. Barabash, D. Popov, G. Shen, C. Park and W. Yang Multiscale twin hierarchy in NiMnGashape memory alloys with Fe and Cu. ActaMaterialia, 2015, 87, 344-349