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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·F. R. Drymiotis
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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.

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C. H. Booth, A. D. Christianson, J. M. Lawrence, L. D. Pham, J. C. Lashley, F. R. Drymiotis. 2006-11-07. Ytterbium divalency and lattice disorder in near-zero thermal expansion YbGaGe. https://doi.org/10.1103/physrevb.75.012301

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