South Australian and CSIRO researchers recently put the Australian Synchrotron’s x-ray absorption spectroscopy (XAS) beamline under extreme pressure. Six hundred times atmospheric pressure, to be more specific.

IMAG0832_ZOE010web.jpgIn October 2009, a collaborative team from the University of Adelaide and CSIRO created extreme temperature and pressure ‘deep earth’ conditions in a specialised experimental cell on the XAS beamline. In July 2013, they came back for more.

Associate Professor Joël Brugger and his team from the University of Adelaide (Dr Barbara Etschmann and honours students Orddom Leav and Yolanda Sam) and CSIRO (Drs Weihua Liu and Stacey Borg) set up their highly-specialised hydrothermal spectroscopic cell, mAESTRO, in the newly commissioned second experimental hutch on the XAS beamline. The second hutch is specifically designed to accommodate large roll-in, roll-out equipment, such as that required for extreme chemistry, high-temperature and high-pressure measurements. In combination, the mAESTRO and the XAS beamline form one of only two world facilities where reactions can routinely be studied by in-situ XAS up to supercritical conditions.

Photo above: Mechanical engineering honours students Yolanda Sam and Orddom Leav setting up in the XAS beamline’s second experimental hutch. Image: Weihua Liu

Joël and his colleagues are interested in metal speciation and chemistry in hydrothermal fluids, which play an important role in natural and man-made systems, such as the formation of ore deposits in the Earth’s crust, the chemical processing of minerals, and corrosion in power plants. On previous visits to the Synchrotron, they have checked the optical geometry and other characteristics of their revolutionary hydrothermal cell.

During their latest visit, the team conducted further tests and commissioned the mAESTRO cell for future experiments that will enable them to take routine measurements of supercritical fluids under ‘hellish’ deep-earth conditions up to around 600°C and 600 times atmospheric pressure. They plan to make good use of a dedicated fluorescence detector currently being commissioned by beamline staff.

Available only at synchrotrons, XAS enables in-situ study of the molecular structure and composition of fluids. As a result of the small sample size and the thickness of the beryllium windows required to contain the extreme pressures, the team’s experiments are only possible at third-generation synchrotrons, such as the Australian Synchrotron.

“We’re looking forward to experimentally investigating the behaviour of hydrothermal systems under extreme temperatures and pressures,” Joël said. “This capability will enable us to contribute to improved predictive mineral exploration strategies, more efficient mineral and metallurgical processing techniques; and better modelling of geothermal energy and geo-sequestration strategies, leading to safer, more efficient and cost-effective operations.”

Construction of the hydrothermal XAS cell was made possible by a LIEF grant awarded to University of Adelaide, Monash University, CSIRO and the Australian Synchrotron. The commissioning work undertaken in July 2013 formed part of an honours project for two mechanical engineering students at the University of Adelaide.

Read about the earlier experiment.