Acoustic relaxation and internal strains in KCl:CN

Data revealing a previously predicted relaxation peak in the propagation of T_2g mode ultrasound in KCl doped with 15–140 ppm KCN is presented and analyzed. A distribution of activation energies is found; the mean value is identified with a thermal conductivity resonance, and the width of the distribution is taken to confirm Pompi's assumption of internal strains in his analysis of specific heats and electric field dichroism in KCl:CN. The interaction of internal strains with the rotational components of the measuring shear wave suggests new sources for the observed acoustic effects in KCl:CN.