HR: 15:10h
AN: MR13B-07 INVITED     [Abstracts]
TI: Performance of the COMPRES multi-anvil high-pressure assemblies
AU: * Leinenweber, K
EM: kurtl@asu.edu
AF: Dept. of Chemistry and Biochemistry, Arizona State University, Tempe, AZ 85287-604 United States
AU: Tyburczy, J
EM: Jim.Tyburczy@asu.edu
AF: Dept. of Geological Sciences, Arizona State University, Tempe, AZ 85287-1404 United States
AU: Sharp, T
EM: tom.sharp@asu.edu
AF: Dept. of Geological Sciences, Arizona State University, Tempe, AZ 85287-1404 United States
AU: Soignard, E
EM: emmanuel.soignard@asu.edu
AF: Dept. of Geological Sciences, Arizona State University, Tempe, AZ 85287-1404 United States
AU: Diedrich, T
EM: Tamara.Diedrich@asu.edu
AF: Dept. of Geological Sciences, Arizona State University, Tempe, AZ 85287-1404 United States
AU: Petuskey, W
EM: WPetuskey@asu.edu
AF: Dept. of Chemistry and Biochemistry, Arizona State University, Tempe, AZ 85287-604 United States
AU: Mosenfelder, J
EM: jed@gps.caltech.edu
AF: Division of Geological and Planetary Sciences, Mail Code 170-25 California Institute of Technology, Pasadena, CA 91125 United States
AB: As part of the COMPRES program, we have undertaken to create a suite of multi-anvil cell assemblies that are well-calibrated, with all the parts traceable and consistent over time, relatively inexpensive, and available to the whole scientific community. This effort has been ongoing for over three years, resulting in a series of assemblies that are based on completed parts ready to assemble, suitable for use at peak simultaneous pressures and temperatures of 23 GPa and 2000 degrees C (8/3 assembly). The assemblies are based on both traditional and new designs, and involve novel components such as highly reproducible and inexpensive injection-molded ceramic octahedra, laser-cut rhenium furnaces (8/3 and 10/5 assemblies), ceramic sleeves with thermocouple grooves and other features already machined in, and other developments. The pressure efficiency of the assemblies is very comparable to others with the same truncation sizes, and they appear to be relatively gentle to carbide (low blowout and breakage rate, etc) and have good thermocouple and furnace success rates. This presentation will focus on the performance of the assemblies and their suitability for various types of scientific research. For the assemblies designed for conventional offline experiments (8/3, 10/5, 14/8 box furnace and step furnace, 25/15 "offline" assemblies), the pressure calibration curves, effect of temperature on pressure, and the accuracy and repeatability of the calibrated pressure will be discussed. Pressure calibrations were done using high-temperature fixed points, along with in-situ measurements at the beam line on the unmodified assemblies. In order for the in-situ calibrations to be applicable in the laboratory, they were done on the unmodified "offline" assemblies including all the x-ray absorbers such as zirconia, lanthanum chromite and/or rhenium. The in-situ measurements used a pressure standard developed for this purpose composed of a strongly scattering mixture of CsCl and W. Thermal gradients were also examined, using a finite-difference thermal model and in-situ measurements. A parallel series of assemblies specially modified for in-situ x-ray diffraction, referred to as the "online" assemblies, was also developed. These assemblies are based on rectangular alumina windows through lanthanum chromite parts and vertical slits in rhenium furnaces (8/3 and 10/5 assemblies), or on equatorial MgO windows combined with mullite octahedra for combined x-ray translucency and thermal insulation (14/8 assembly; see Mosenfelder et al., this volume). The "online" assemblies are suitable for study using x-rays in the energy range from 20 - 100 keV. Examples will be given from recent research projects, including the observation of transition behavior in mantle materials such as olivine.
DE: 3630 Experimental mineralogy and petrology
DE: 3694 Instruments and techniques
DE: 3934 Optical, infrared, and Raman spectroscopy
DE: 3954 X-ray, neutron, and electron spectroscopy and diffraction
SC: Mineral and Rock Physics [MR]
MN: Fall Meeting 2005