Effect of H on the crystalline and magnetic structures of the Y-Co3 H(D) system. II YCo-H(D) from X-ray and neutron powder diffraction

Liu, J; Cui, X-Y; Georgiev, P A; Morrison, I; Ross, DK; Roberts, M; Anderson, KA; Telling, M; Fort, D

Abstract

The crystalline and magnetic structures of the YCo3
-H(D) system have been investigated by means of x-ray
and neutron diffraction with the objective of understanding the complex magnetic changes that are observed in
this system as hydrogen is added. Synchrotron x-ray diffraction (XRD) patterns were first refined to yield the
lattice parameters and coordination of Y and Co atoms in the metal and two B-hydride phases while XRD was
used for the y phase. In situ neutron powder diffraction measurements of YCo3Dx were then made in all four
phases to determine the deuterium site occupancies and magnetic structures. The site occupancies were also
rationalized using the Westlake geometric model. The highest hydrogen concentration measured was
YCo3H4.6
. Using the Westlake model, we conclude that the saturated hydrogen content would be YCo3H5
. Our
results reported here and in Part I (Phys. Rev. B 76, 184443 (2007)) have enabled us to rationalize the changes
in the magnetic structures in terms of changes in the cobalt-cobalt distance caused by the addition of hydrogen.
In particular, in the antiferromagnetic y phase, we observe Co atomic displacements that enable the structure
to adopt a particular antiferromagnetic structure in a manner that is reminiscent of a Peierls distortion as
observed in transitions from the conducting to nonconducting hydrides on addition of hydrogen in YH3.

Citation

Liu, J., Cui, X., Georgiev, P. A., Morrison, I., Ross, D., Roberts, M., …Fort, D. (2007). Effect of H on the crystalline and magnetic structures of the Y-Co3 H(D) system. II YCo-H(D) from X-ray and neutron powder diffraction. Physical review B: Condensed matter and materials physics, 76(1), 184444-1. https://doi.org/10.1103/PhysRevB.76.184444

• Journal Article Type: Article
• Publication Date: Jan 1, 2007
• Deposit Date: Apr 23, 2012
• Publicly Available Date: Apr 5, 2016
• Journal: Physical Review B
• Print ISSN: 1098-0121
• Publisher: American Physical Society
• Peer Reviewed: Peer Reviewed
• Volume: 76
• Issue: 1
• Pages: 184444-1
• DOI: https://doi.org/10.1103/PhysRevB.76.184444
• Publisher URL: http://dx.doi.org/10.1103/PhysRevB.76.184444