YbGaGe

YbGaGe is an alloy of Ytterbium, Gallium and Germanium. It sparked interest because one group of researchers reported that it exhibits zero thermal expansion, while being conductive.^[1] Such materials have applications in space and other environments where low thermal expansion materials are required.^[2] Subsequent measurements by other groups were however not able to reproduce their results, but rather found expansion coefficients similar to copper.^[3]

Nevertheless, YbGaGe does show anomalous thermal expansion. Near zero thermal expansion was observed by Booth etal. It was found that near-zero thermal expansion (NZTE) in YbGaGe is sensitive to stoichiometry and defect concentration, however, the NZTE mechanism remains elusive ^[4]

References

1. "Zero thermal expansion in YbGaGe due to an electronic valence transition" Letter by James R. Salvador, Fu Guo, Tim Hogan & Mercouri G. Kanatzidis in Nature 425, 702-705 (16 October 2003) | doi:10.1038/nature02011; Received 5 March 2003; Accepted 19 August 2003
2. "Zero Expansion Conductor". October 20, 2003. p. 1. Retrieved May 23, 2011.
3. "YbGaGe: normal thermal expansion"
4. [Ytterbium divalency and lattice disorder in near-zero thermal expansion YbGaGe, Phys. Rev. B 75, 012301 – Published 3 January 2007, C. H. Booth, A. D. Christianson, J. M. Lawrence, L. D. Pham, J. C. Lashley, and F. R. Drymiotis]