Journal of Low Temperature Physics

, Volume 7, Issue 1–2, pp 43–75

Thermal expansion of copper, silver, and gold at low temperatures

  • G. K. White
  • J. G. Collins
Article

Abstract

Improvements have been made in a differential dilatometer using the three-terminal capacitance detector. The dilatometer is of copper and has been calibrated from 1.5–34 K in an extended series of observations using silicon and lithium fluoride as low-expansion reference materials. The expansion of silver and gold samples has been measured relative to the dilatometer, while the calibrations themselves have been used to determine the expansion of copper relative to the reference materials. Analyses of six sets of observations indicate that below 12 K the linear expansion coefficient α of copper is represented by
$$10^{10} \alpha = (2.1_5 \pm 0.1){\rm T} + (0.284 \mp 0.005){\rm T}^3 + (5 \pm 3) \times 10^{ - 5} T^5 K^{ - 1} $$
corresponding to respective electronic and lattice Grüneisen parameters γe=0.93 and γ01=1.78. Measurements on oxygen-free silver yield
$$10^{10} \alpha = (1.9 \pm 0.2){\rm T} + (1.14 \mp 0.03){\rm T}^3 + (2 \pm 2) \times 10^{ - 4} T^5 K^{ - 1} $$
below 7 K, whence γe ≃ 0.97, γ01=2.23. By contrast, silver containing ca. 0.02 at. % oxygen showed a much larger expansion at the lowest temperatures: below 7 K, 1010α ∼ 7T+1.19T3. We have not been able to obtain an unambiguous representation for gold, but find a reasonable fit below 7 K to be
$$10^{10} \alpha \simeq (1 \pm 0.5){\rm T} + (2.44 \mp 0.05){\rm T}^3 - (5 \pm 1) \times 10^{ - 3} T^5 K^{ - 1} $$
with γ1 ≃ 2.94 and γe ≳ 0.7 (free-electron value).

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Copyright information

© Plenum Publishing Corporation 1972

Authors and Affiliations

  • G. K. White
    • 1
  • J. G. Collins
    • 1
  1. 1.CSIRO Division of PhysicsNational Standards LaboratorySydneyAustralia

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