Ultrasonic attenuation studies in deuterated and undeuterated chromium potassium alum

The attenuation of 10‐ and 30‐MHz sound waves in deuterated and undeuterated chromium potassium alum have been measured over the temperature range 300–4.2 K. A very large attenuation peak occurs in the temperature range 70–160 K. It is believed that this is associated with phonon‐phonon scattering.