Elastic Constants of Mercury Selenide

The elastic constants of mercury selenide from 4.2 to 300 K have been determined from 10-MHz sound-velocity measurements utilizing the pulse-echo technique. The constants $c_{11}$, $c_{12}$, and $c_{44}$ range from 6.900×${10}^{11}$, 5.105×${10}^{11}$, and 2.3073×${10}^{11}$ dyn/${\mathrm{cm}}^2$, respectively, at 0 K to 5.950×${10}^{11}$, 4.307×${10}^{11}$, and 2.2015×${10}^{11}$ dyn/${\mathrm{cm}}^2$, respectively, at 300 K. The shear modulus $c_s=0.899\mathrm{}\times {10}^{11}$ dyn/${\mathrm{cm}}^2$, compressibility ${\beta }^{\mathrm{el}}=1.753\mathrm{}\times {10}^{-12\mathrm{}}$ ${\mathrm{cm}}^2$/dyn, and the low-temperature limit of the Debye characteristic temperature $\Theta _0^{}{}_{}{}^{\mathrm{el}}=151\mathrm{}$ K are deduced from values of the elastic constants at 0 K obtained by extrapolation. The reststrahlen frequency as given by the Szigeti relation is 5.12×${10}^{13}$ Hz. From theoretical and empirical relations, the ionicity of HgSe is estimated to be $\frac{e^{*}}{e}=0.7\mathrm{}\pm 0.1$. The behavior of the elastic constants and the ionicity of HgSe are compared with the characteristics of other II-VI compounds that have the zinc-blende crystal structure.