Elastic Constants of Silver and Gold

The three elastic constants ${\mathrm{C}}_{44}$, $\frac{1}{2}(C_{11}-C_{12})$, and $\frac{1}{2}(C_{11}+C_{12}+2\mathrm{}{C}_{44})$ have been directly measured for silver and gold in the temperature range between 4.2 and 300°K. The various contributions to the values of the 0°K constants are analyzed in terms of a simple model which quite successfully describes copper. It is concluded that such a model is unsatisfactory when applied to the heavier noble metals because these appear to have large noncentral forces contributing to their constants. Combined with pressure data the present results show the elastic constants to be explicit functions of temperature. The Debye characteristic temperatures calculated from the 0°K elastic constants are shown to be in substantial agreement with the results from calorimetry.