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 c₁₁, c₁₂, and c₄₄ range from 6.900×{}10¹¹, 5.105×{}10¹¹, and 2.3073×{}10¹¹ dyn/cm², respectively, at 0 K to 5.950×{}10¹¹, 4.307×{}10¹¹, and 2.2015×{}10¹¹ dyn/cm², respectively, at 300 K. The shear modulus cₛ=0.899×10¹¹ dyn/cm², compressibility βᵉˡ=1.753×10^-12 cm²/dyn, and the low-temperature limit of the Debye characteristic temperature Θ₀^_ᵉˡ=151 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×{}10¹³ Hz. From theoretical and empirical relations, the ionicity of HgSe is estimated to be e*e=0.7±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.