Lattice dynamics of simple superionic conductors

Using harmonic lattice dynamics we are able to calculate 1st order Raman results in the superionic conducting phases of AgI and CuI. We find that much of the calculated response is allowed because of the structural disorder that occurs in these materials. The evidence for the 1st order nature of the experimental results is given and the calculation is compared to experiment. It is also pointed out that Raman experiments (and calculations) can be performed on oriented single crystals of these disordered cubic materials yielding response that transforms as the A, E, and T irreducible representations of the cubic point groups.