“…Sulfide materials, discussed in more detail below, are of interest for this reason. In terms of conductivity, it is clear that oxide glasses have significantly lower conductivities than those of sulfide materials (Boukamp and Huggins, 1978;Elmoudane et al, 2000;Ito et al, 1983;Mercier et al, 1981b;Murayama et al, 2004).…”