We investigate the effects of carbon and boron doping on the thermal expansion in the hexagonal (P63/mmc) intermetallic YbGaGe. X-ray powder diffraction was used to measure the lattice constants on pure and doped (C or B at nominal levels of 0.5 %) samples from T~10 K to T~300 K. Also measured were resistivity, specific-heat, and magnetic susceptibility. While the pure YbGaGe samples exhibit positive thermal volume expansion, (V300K-V10K)/V300K = 0.94%, the volume expansion in the lightly C and B-doped samples, contract and tend towards zero volume expansion. Such a strong response with such light doping suggests that the underlying mechanism for the reported zero volume expansion is substitutional disorder, and not the previously proposed valence fluctuations.
@article{arxiv.cond-mat/0410489,
title = {Tunable Thermal Expansion Behavior in the Intermetallic YbGaGe},
author = {F. R. Drymiotis and Y. Lee and G. Lawes and J. C. Lashley and T. Kimura and S. M. Shapiro and A. Migliori and V. Correa and R. A. Fisher},
journal= {arXiv preprint arXiv:cond-mat/0410489},
year = {2009}
}