The Specific Heat of Lead in the Temperature Range 1°K to 75°K

Abstract

The specific heat of pure Pb in the temperature range 1\ifmmode^\circ\else\textdegree\fi{}K to 75\ifmmode^\circ\else\textdegree\fi{}K has been measured calorimetrically, both in the normal and superconductive states. The measurements were made using a useful semiautomatic recording system. It was found that at the lowest temperatures (1\ifmmode^\circ\else\textdegree\fi{}K to 4\ifmmode^\circ\else\textdegree\fi{}K) the lattice specific heat of Pb in the normal state was a ${T}^{3}$ function, with a Debye $\ensuremath{\theta}=96.3$\ifmmode^\circ\else\textdegree\fi{}K. It was found that the variation of $\ensuremath{\theta}$ with temperature over the whole range of temperature employed confirmed the theoretical computations made by Leighton for f.c.c. lattices. The normal electronic specific heat was found to be $7.48\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4} T$ cal/mole-deg, in good agreement with results from magnetic measurements on superconducting Pb. The measured value of the electronic specific heat of the superconducting state was ${C}_{el,s}=5\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}5} {T}^{3}$ cal/mole-deg, in the temperature range 1\ifmmode^\circ\else\textdegree\fi{}K to 4\ifmmode^\circ\else\textdegree\fi{}K; this result was also in agreement with the magnetic measurements.