Specific heat of (KBr)1−x(KCN)xfrom 1 to 25 K

The specific heat of (KBr${)}_{1\mathrm{-}\mathrm{x}}$(KCN${)}_{\mathrm{x}}$ for x=0.0, 0.19, 0.41, and 0.60 has been measured from 1.5 to 25 K. The data are compared with the theory developed by Grannan, Randeria, and Sethna [Phys. Rev. Lett. 60, 1402 (1988)] to describe the specific heat of (KBr${)}_{1\mathrm{-}\mathrm{x}}$(KCN${)}_{\mathrm{x}}$ at intermediate temperatures through the librational motion of ${\mathrm{CN}}^{\mathrm{-}}$ ions modeled as interacting elastic dipoles. Data are also presented on the specific heat of KI between 1.5 and 30 K. We review (KBr${)}_{1\mathrm{-}\mathrm{x}}$(KCN${)}_{\mathrm{x}}$ elastic-constant data for $c_{44}$ and $c_{11}$ at 4.2 K and $c_{12}$ at 300 K.