The thermal expansion of pure metals and the possibility of negative coefficients of volume expansion

Abstract
The dominant factors controlling the volume thermal expansion of solids are discussed. It is shown that if the Fermi energy of the electron gas has a value for which the density of states of the electrons changes sufficiently rapidly with energy, a negative coefficient of volume expansion may reasonably be expected, particularly if this is associated with a high electronic specific heat from a large number of overlapping bands. It is suggested that this is the reason underlying the observed negative coefficient of volume expansion of the cubic phase in plutonium.