X-ray-absorption fine structure determination of pressure-induced bond-angle changes in ReO{sub 3}
- Department of Physics, MS-68, Eastern Washington University, Cheney, Washington 99004 (United States)
- Department of Physics, Box 351560, University of Washington, Seattle, Washington 98195 (United States)
We report here on a Marquardt-type method to fit the x-ray absorption fine structure (XAFS) of ReO{sub 3}. We find that, when the ambient-pressure structure of ReO{sub 3} is used as a starting point, the pressure dependence of the angle of the Re-O-Re bond in ReO{sub 3} is fairly straightforwardly and robustly determined using FEFF curved-wave, multiple-scattering programs and is accurate to about {+-}1.5 degree sign or better. We present an argument that XAFS and scattering experiments fundamentally differ in what they measure in the case of nearly linear atomic bridges. Focussed multiple-scattering paths involving the Re-O-Re bridge make a contribution to the XAFS spectrum that is sensitive to the rms deviation of oxygen from the [100]-type directions. Fits to simulated spectra back up our contention that for XAFS experiments the effective position of the oxygen atom is its rms displacement whether the average displacement is zero or not. (c) 2000 The American Physical Society.
- OSTI ID:
- 20215618
- Journal Information:
- Physical Review. B, Condensed Matter and Materials Physics, Vol. 61, Issue 10; Other Information: PBD: 1 Mar 2000; ISSN 1098-0121
- Country of Publication:
- United States
- Language:
- English
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