Thermal Expansion of Aluminum at Low Temperatures

Abstract

The pressure of the electron gas gives rise to a contribution to the thermal expansion of metals proportional to the dilatational strain derivative of the electronic specific heat. It appears from the strain dependence of the superconducting phase boundary that the electronic specific heat of aluminum is extremely sensitive to dilatation. This would explain why the thermal expansion of aluminum between 20\ifmmode^\circ\else\textdegree\fi{} and 30\ifmmode^\circ\else\textdegree\fi{}K is much larger than expected from the Gr\"uneisen theory. The extreme sensitivity of the electronic specific heat to strain is not inconsistent with the zone structure of aluminum.