A combination of a Drickamer anvil apparatus and monochromatic X-rays for stress and strain measurements under high pressure.

A modified Drickamer anvil apparatus has been developed to combine with monochromatic synchrotron radiation for high-pressure X-ray diffraction and radiography in the GSECARS bending-magnet station, 13-BM-D, at the Advanced Photon Source, Argonne, USA. Using this experimental set-up, deformation experiments can be carried out at pressures in excess of 30 GPa at high temperatures. Differential stresses and total axial strains of polycrystalline platinum and Mg(2)SiO(4) ringwoodite have been measured up to 32 GPa at room temperature using tungsten carbide anvils. The total axial strain of the platinum increases with pressure and reaches about 55% at the highest pressure. A test run using a composite sintered diamond anvil system was performed. The use of X-ray-tranparent anvils enables the entire Debye rings to be observed up to 10 degrees 2theta. With high-energy photons (65-70 keV), this allows a coverage in Q (= 2pi sintheta/lambda) to about 3 A(-1), thus making it possible to evaluate hydrostatic pressure and differential stress in crystalline minerals using diffraction. This, coupled with the ability to determine axial strain, allows deformation studies to be performed to pressures above 30 GPa.