In situ probing of the structure and properties of materials at extreme conditions of high pressures and temperatures using X-ray diffraction techniques is an increasingly demanding requirement, particularly in Earth and materials sciences. Without synchrotron radiation, the user is limited and blind to the many processes that may occur in a compressed and heated sample. Nor can the pressure, temperature, stress and strain (rate) be accurately recorded over time. In addition, real-time imaging of the sample, as it undergoes changes at extreme conditions, is only possible using a synchrotron source. In contrast to LVP techniques, the diamond anvil cell (DAC) technique allows for reaching extremely high pressures to the core of the Earth. However, sample volume is restricted to a few tens of micrometres, preventing careful study on more than one phase in the sample (phase-mixtures) and of grain boundary transport & mechanical properties.

            At the PETRA III P61B beamline, a 6-ram LVP is in operation since 3 years (Fig. 1a,b). This state of the art 15 MN press has extremely precise ram control for reaching high pressures with a significantly low rate of anvil breakage. Routine experiments are possible up to 20 GPa (Fig. 1c), with a special set up envisaged to reach 25 GPa in kawai ‘6-8’ geometry on mm-sized samples. Even higher pressure generation is possible with modified user-provided WC anvils to reach 40+ GPa with >2000 K heating, and with sintered diamond anvils to reach 60+ GPa on sub-mm sized samples. In addition, cubic ‘6-6’ compression geometry is offered to synthesize nearly cm-sized samples up to 4-5 GPa and generate pressures up to ~15 GPa for controlled rock deformation (anisotropic compression). The LVP at beamline P61B is therefore well-suited for extreme conditions research using versatile set ups. The beamline also offers a fully equipped sample preparation laboratory for users.

       First beam is expected to be available since August 2019. The white beam will have usable peak flux between 10¹¹ and 10¹² ph/s/mm²/0.1%b.w. in the range of 30 to 150 keV from 10 wigglers (the nearest one at 133 m distance to the Experimental Hutch). Initial beam size is limited to 1.5 mm x 1.5 mm. Commissioning will begin using a solid-state, high-purity Ge detector for ED-XRD and an X-ray microscope for imaging (Fig. 1d). The instruments are mounted on a temporary positioning system (i.e. table with stages) and will be used until the delivery of the complete positioning system, built by Kohzu, sometime in April 2020. A second Ge-detector will then be added. The first call for user beam time will likely be announced in the coming months, pending the usability of the temporary detector set up for in situ high-pressure experiments in the LVP. The LVP beamline will operate with beam on a 50% basis with Helmholtz Zentrum Geesthacht (HZG) – P61A and P61B LVP. Therefore, the LVP is also available for ex situ studies. Proposals for ex situ studies can be submitted anytime and will be reviewed by the beamline manager.