Brillouin Scattering and Synchrotron X-Ray Measurements at GSECARS, Advanced Photon Source: Simultaneous Measurements of Sound Velocities and Density
Abstract
A Brillouin spectrometer have been installed and successfully tested at the GSECARS Sector 13 (BMD line) of the Advanced Photon Source (APS). It is now possible to perform simultaneous measurements of density (by x-ray diffraction) and sound velocities (by Brillouin scattering) on transparent single crystal and polycrystalline materials at high pressure and temperatures. This allows the determination of an absolute pressure scale. The equation of state and acoustic velocities and, hence, elastic moduli of materials as a function of pressure and temperature can now be determined without resort to a secondary pressure standard, such as the ruby fluorescence scale. We describe here the design of the system and the first experimental results obtained from this unique facility. Some of the important design characteristics for the system are: 1) it is user-friendly, and a general user can operate the system without being an expert. 2) it requires minimal set-up time and does not require frequent alignment of the optics; 3) all control and adjustment of optics normally performed during a Brillouin experiment can be performed from outside the hutch; 4) it is flexible with respect to sample position and compatible with powder and single-crystal x-ray diffraction techniques, while not interfering with the other experimental techniques used on the beamline. We have measured a single crystal elasticity of NaCl (B1) and MgO to 30 GPa, and aggregate velocities and elastic moduli of NaCl (B2) to over 70 GPa. High P and T measurements were also performed, demonstrating the potential of this system for PVT equations of state measurements over a broad range of conditions.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2005
- Bibcode:
- 2005AGUFMMR31A0120B
- Keywords:
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- 3909 Elasticity and anelasticity;
- 3919 Equations of state;
- 3924 High-pressure behavior;
- 3954 X-ray;
- neutron;
- and electron spectroscopy and diffraction;
- 3994 Instruments and techniques