The thermal conductivity of silver iodide

We have measured the thermal conductivity of pressed pellets of 99.999% AgI from 120 K to 500 K using a transient hot wire method. The temperature dependence changes from T^?1.3±0.1 at the lowest temperatures to T^?1.8±0.1 below the phase transition at 420 K. Above this phase transition where AgI is a superionic conductor we see a weak temperature dependence T^+0.5±0.1. These results indicate shortening of the phonon mean free path at high temperatures due to the mobile Ag⁺ ions.