HR: 1330h
AN: V42A-0334    [PDF]
TI: In Situ High Pressure Angle Dispersive X-ray Diffraction Experiments:With Sagittally-Bent Double Laue Monochomator
AU: * Hu, J
AF: Geophysical Laboratory of CIW, 5251 Broad Branch Rd, N. W., Washington, DC 20015
AU: Zhong, Z
AF: The NSLS of BNL, X17B Bldg. 725 BNL, Upton, NY 11973
AU: Liu, H
AF: Geophysical Laboratory of CIW, 5251 Broad Branch Rd, N. W., Washington, DC 20015
AU: Guo, Q
AF: Geophysical Laboratory of CIW, 5251 Broad Branch Rd, N. W., Washington, DC 20015
AU: Mao, H
AF: Geophysical Laboratory of CIW, 5251 Broad Branch Rd, N. W., Washington, DC 20015
AU: Hemley, R J
AF: Geophysical Laboratory of CIW, 5251 Broad Branch Rd, N. W., Washington, DC 20015
AB: A Sagittally-bent double Laue monochomator is used at the wiggler beam line X17C of NSLS, BNL. It can provide high-energy X-ray tunable from 20 keV to 40 keV. The monochomator consists of two Si crystals of 0.76 mm thick, with surface corresponding to the (001) planes. The 111 reflections of both crystals are used to diffract the x-ray. The two crystals are bent Sagittelly to 1 m radius and used in the Laue mode [1, 2]. The bent Laue crystals provide high energy-resolution beam with a flux one order of magnitude greater than that of a flat-crystal monochromator. For high-pressure diamond-anvil cell experiments using angular dispersive x-ray diffraction, K-B mirrors are used to focus the incident beam from 0.180mm x 0.180mm to 0.025mm x 0.025mm. Two samples were studied with different x-ray energies. The Ag2O2 sample was studied at pressures up to 20 GPa using energy of 38.9246 keV (0.031851 nm) x-ray. The problem of strong Ag fluorescence causing Ge-detector to saturate in energy dispersive x-ray diffraction was not an issue in the present angular dispersive experiments. With energy of 30.4912keV (0.040663 nm) x-ray, NaMgF3 was studied to 30 GPa. Exposure time was 1 to 6 minutes for different pressures. No phase transition was found in the pressure range. The P-V data fitting to a third order Birch- Murnahgan equation yields a bulk modulus Ko=68.9 1.7 GPa and Ko­_=6.3. [1] Z. Zhong, et. al., Acta. Cryst. A 59 (2003) 1-6 [2] Z. Zhong, et. al. J. Appl. Cryst., 34 (2001) 646-653
DE: 3600 MINERALOGY AND PETROLOGY (replaces
DE: 5100 PHYSICAL PROPERTIES OF ROCKS
DE: 7200 SEISMOLOGY
DE: 8100 TECTONOPHYSICS
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2003 Fall Meeting