By using 63Cu nuclear magnetic resonance techniques, exchanges were observed between the non-equivalent Cu sites in crystalline samples of the mineral, argyrodite. At temperatures below 200K, where the motion of the Cu(I) ions was slow, it was possible to distinguish several non-equivalent Cu sites. Upon increasing the temperature, chemical exchanges between the non-equivalent cation sites was detected in the 63Cu nuclear magnetic resonance spectra. The activation energy for this motion was deduced to be equal to 35kJ/mol. This value was consistent with the reported ionic conductivity.

Ionic Diffusion in Cu6PS5Br studied by 63Cu NMR. H.Ohki, K.Harazono, T.Erata, A.Tasaki, R.Ikeda: Zeitschrift für Naturforschung, 1993, 48a[10], 1005-8