Extended x-ray-absorption fine-structure study of copper under high pressure

Journal Article · Thu Jun 15 04:00:00 EDT 1989 · Phys. Rev. B: Condens. Matter; (United States)

DOI:https://doi.org/10.1103/PhysRevB.39.12537· OSTI ID:6227113

Freund, J; Ingalls, R; Crozier, E D

We examine copper as a pressure calibrant for extended x-ray-absorptionfine-structure (EXAFS) measurements of solids under pressures ranging from 0 to10 GPa. Great care must be exercised both in the theoretical formulation ofEXAFS and in the data analysis in order to achieve the high precision requiredto make copper a useful pressure marker. From the first-shell /ital k/-spacedata, phase and amplitude information is extracted both with the ratio methodand from fitting parameters with the help of theoretically calculatedcentral-atom phase shifts (B.-K. Teo and P. A. Lee, J. Am. Chem. Soc.101, 2815 (1979)) and curved-wave backscattering phase shiftsand amplitudes (A. G. McKale /ital et/ /ital al/., J. Am. Chem. Soc.110, 3763 (1988)). Both techniques yield practically identicalresults confirming the reliability of the phase and amplitude tabulations. Butboth techniques suffer from the ambiguity that the results depend on how manyEXAFS parameters are kept variable. It is shown that, for copper, onlynearest-neighbor distances and second cumulants (EXAFS Debye-Waller factors)have to be taken into account. Then pressures can be determined with anaccuracy of about 0.5 GPa. We also present two models for the pressuredependence of the second cumulant: (1) a correlated Debye model along withsimple parametrizations of the isothermal equation of state and theGr/umlt u/neisen parameter, and (2) a model for the calculation of the moments ofthe nearest-neighbor distance distribution from an expansion to third order ofthe potential energy. Both models confirm our data analysis.

• Research Organization: Department of Physics (FM-15), University of Washington, Seattle, Washington 98195(US); Department of Physics, Simon Fraser University, Burnaby, British Columbia, Canada V5Aat/B1S6
• OSTI ID: 6227113
• Journal Information: Phys. Rev. B: Condens. Matter; (United States), Journal Name: Phys. Rev. B: Condens. Matter; (United States) Vol. 39:17; ISSN PRBMD
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360104* -- Metals & Alloys-- Physical Properties
ABSORPTION SPECTRA
CALIBRATION STANDARDS
CONTAINERS
COPPER
DATA ANALYSIS
ELEMENTS
FINE STRUCTURE
METALS
PRESSURE DEPENDENCE
PRESSURE MEASUREMENT
PRESSURE VESSELS
SPECTRA
STANDARDS
TRANSITION ELEMENTS
VERY HIGH PRESSURE
X-RAY SPECTRA