The instrument is dedicated to the determination of physical characteristics of materials under high pressure and temperature conditions, using a 2000 ton force large-volume device.

Status: open


We operate in 3 modes: with 1- or 2- compression stages and 1-stage for deformation studies. Diffraction data are collected in monochromatic mode at energies of typically 33 or 55 keV, generated from the emission of a U18 undulator, and selected by a Cinel Si(111) monochromator with beam-position feedback. Beam sizes are typically 1 mm^2, when not limited by anvil gaps. We use a variety of detectors: mar345, DT linear detector and a Bicron scintillator. The DT device is mounted on a beam-axial rotation allowing the collection of 2TH data as a function of azimuth, well-suited for deformation studies, or for integration as per usual 2D detectors. This device has a time resolution of 0.1 sec for one static azimuthal point at full 2TH range (51 seconds for full solid-angle) and is fully triggerable for automation of phase diagram, pVT, or kinetic measurements. The scintillator is a high spatial resolution device with an effective radius of approximately 1350 mm and is downstream collimated with adjustable slits. We also have a 16-bit x-ray camera with approx 2 micron resolution, which, with rebinning, can resolve changes in sample lengths to approximately 1/10th of this.

In 1-stage mode we can operate with horizontal or vertical furnaces, mounted in 10 mm EL B:epoxy cubes and compress samples to 10 GPa. Temperatures obtained with a graphite furnace (2.9 mm OD, typical) can exceed 1800 K. This assembly is modified, by introducing hard alumina pistons, for deformation studies. These make use of the independent U and D primaries of the press tooling to change the shape of the sample under load. This can be both contracting and extending, and can be cycled through null stress states. Deformation studies too are conducted to 10 GPa, at high temperature, with strain rates of 10-6 sec-1 (typical) to a maximum strain of 30-35%. Data collections are azimuthal and code exists for their online treatment.

Two-stage experiments are currently offered to Users to 20 GPa and 2000 K, using a variety of sample geometries - 25 mm to 7 mm octahedra are used. Given the natural geometry of our cubic device, regular sample geometry is complex, however, we will run horizontal or vertical furnace geometries should the need require. To 10 GPa, graphite furnaces are most popular and, at higher loads, a rhenium foil furnace is used. These are cut in-house with special windows to avoid absorption. While transparent anvil and slit assembly testing continues, 2-stage experiments are only offered with carbide assemblies. Data collection is then in the horizontal plane, using the scintillator (to 0.6 \AA) or to about 0.8 \AA with the DT linear device. The use of the latter improves time resolution by a factor of >10k, but at the cost of increased background scatter.

Sample alignment is by x-ray camera or photodiode on its 9 independent axes (4 x vertical [electronically coupled, mechanically independent]; sample-centering X-Y pair, rotation and further rotation-centering X-Y pair). The press is then mounted on an omega stage, allowing the collection of single-crystal datasets, or augmenting the 2TH range possible by working in an asymmetric setting (to 26 deg 2TH h plane, 55 deg v plane). The detector mounts are fully independent of any press movement. All parameters of the experiments are recorded and thermocouple values (for K, C/D, S/R, mV) are read directly by control software. The furnace is controlled manually, using a Eurotherm 2408 unit, which drives the fast-programming 6 kW supplies (high V or high I).