Electrical conductivity measurements revealed that this compound underwent a covalent to superionic phase transition at 328K. The conductivity suddenly changed by a factor of 25 at that temperature, while the activation energy for ionic motion changed from 0.38eV, in the low-temperature form, to 0.26eV in the high-temperature form.

R.B.Beeken, S.M.Wang, D.R.Smith: Solid State Ionics, 1992, 53-56, 220-2