Low temperature specific heat of β-AgI, β-Ag2HgI4, and pyridinium Ag5I6

We have measured the low temperature (∼1.8–20 K) heat capacity of the low temperature phases of the silver fast ion conductors AgI, Ag2HgI4, and pyridinium Ag5I6. All three materials displayed non–Debye heat capacities, however, following analysis of the phonon dispersion, no extraordinary behavior or precursory signs of the fast ion transition are seen.