Ytterbium divalency and lattice disorder in near-zero thermal expansion YbGaGe

C. H. Booth, A. D. Christianson, J. M. Lawrence, L. D. Pham, J. C. Lashley, and F. R. Drymiotis

Phys. Rev. B 75, 012301 – Published 3 January 2007

Abstract

While near-zero thermal expansion (NZTE) in YbGaGe is sensitive to stoichiometry and defect concentration, the NZTE mechanism remains elusive. We present x-ray absorption spectra that show unequivocally that Yb is nearly divalent in YbGaGe and the valence does not change with temperature or with nominally 1% B or 5% C impurities, ruling out a valence-fluctuation mechanism. Moreover, substantial changes occur in the local structure around Yb with B and C inclusion. Together with inelastic neutron scattering measurements, these data indicate a strong tendency for the lattice to disorder, providing a possible explanation for NZTE in YbGaGe.

Received 10 October 2006

DOI:https://doi.org/10.1103/PhysRevB.75.012301

Authors & Affiliations

C. H. Booth^1,*, A. D. Christianson^2,†, J. M. Lawrence², L. D. Pham³, J. C. Lashley⁴, and F. R. Drymiotis⁵

¹Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
²Department of Physics and Astronomy, University of California, Irvine, California 92697-4575, USA
³Physics Department, University of California, Davis, California 95616, USA
⁴Materials Science Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
⁵Department of Physics and Astronomy, Clemson University, Clemson, South Carolina 29634, USA

^*Electronic address: chbooth@lbl.gov
^†Present address: Center for Neutron Scattering, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.

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Vol. 75, Iss. 1 — 1 January 2007

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