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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] However, subsequent measurements by other groups were not able to reproduce those 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 et al. 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]


  1. ^ Salvador, James R; Guo, Fu; Hogan, Tim; Kanatzidis, Mercouri G (2003). "Zero thermal expansion in YbGa Ge due to an electronic valence transition". Nature. 425 (6959): 702–705. doi:10.1038/nature02011. PMID 14562099.
  2. ^ "Zero Expansion Conductor". October 20, 2003. p. 1. Retrieved May 23, 2011.
  3. ^ Janssen, Y; Chang, S; Cho, B. K; Llobet, A; Dennis, K. W; McCallum, R. W; Mc Queeney, R. J; Canfield, P. C (2004). "YbGaGe: Normal thermal expansion". arXiv:cond-mat/0407683.
  4. ^ Booth, C. H; Christianson, A. D; Lawrence, J. M; Pham, L. D; Lashley, J. C; Drymiotis, F. R (2007). "Ytterbium divalency and lattice disorder in near-zero thermal expansion YbGaGe". Physical Review B. 75. arXiv:cond-mat/0611166. doi:10.1103/PhysRevB.75.012301.