Elastic Constants of Indium from 1.4° to 300°K

Abstract

The adiabatic elastic constants of indium have been measured in the temperature range 1.4\ifmmode^\circ\else\textdegree\fi{} to 300\ifmmode^\circ\else\textdegree\fi{}K, using the ultrasonic pulse technique. At 1.4\ifmmode^\circ\else\textdegree\fi{}K no difference between the elastic constants in the super-conducting and normal states is observed to within the available accuracy of about 1 part in ${10}^{4}$. The bearing of this observation on the recent calorimetric data for indium below 1\ifmmode^\circ\else\textdegree\fi{}K is discussed. From the elastic constant data extrapolated to 0\ifmmode^\circ\else\textdegree\fi{}K, the limiting value of the Debye temperature for indium is calculated to be 111.3\ifmmode^\circ\else\textdegree\fi{}K, with an estimated uncertainty of 1%. An extremely large variation with temperature of the shear constant $\frac{({c}_{11}\ensuremath{-}{c}_{12})}{2}$ is observed.