Europhys. Lett., 64 (3) , pp. 344-350 (2003)
Tetrahedral occupancy in the - system observed by in situ neutron powder diffractionM. P. Pitt and E. MacA. Gray
School of Science, Griffith University - Brisbane 4111, Australia E.Gray@griffith.edu.au
(Received 16 April 2003; accepted in final form 29 August 2003)
The crystallography of the - x system has been studied by in situ neutron powder diffraction at 309 , in the supercritical region, and, after quenching in the pure phase to 50 , in the two-phase region at 50 . Rietveld profile analysis of the supercritical diffraction patterns showed that 14% of D interstitials were occupying tetrahedral interstices, in sharp contrast to previous studies at lower temperatures. Tetrahedral occupancy was maintained through the two-phase region at 50 . These results are discussed in the light of first-principles total-energy calculations of hydrogen states in palladium.
61.50.Ks - Crystallographic aspects of phase transformations; pressure effects.
61.72.Dd - Experimental determination of defects by diffraction and scattering.
61.72.Ji - Point defects (vacancies, interstitials, color centers, etc.) and defect clusters.
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