Specific Heat of Lead in the Range from 2 to 8°K

The specific heat of pure lead has been measured in the normal and superconducting states between 2 and 8^∘{}K. The electronic contribution in the superconducting state, Cₑₛ, is derived using γ=3.00 mJ/moledeg² taken from other sources. Near Tc, Cₑₛ is roughly proportional to T3.5, but the dependence becomes more marked as the temperature is reduced. Our data do not conform to the T⁴ dependence deduced from the critical-field curve by Decker, Mapother, and Shaw for 1.2≤T≤5^∘{}K, although the critical field calculated from the difference ΔC=Cₙ-Cₛ agrees with the measured values to within 0.8%. The Debye temperature Θ is deduced from the normal-state results, and a plot of Θ versus T is given. The curve suggests that a maximum in Θ occurs near 1^∘{}K.