Samples were prepared by mixing Ag2S, Hf, and S and heating (168h, 650C). The material crystallized in the cubic system (P4332), with a = 1.09051nm. Structure refinement of 4-circle X-ray data yielded a reliability factor of 4.2%. The 32 S atoms, which were distributed over 2 different positions (24e, 8c), produced 32 octahedra in the unit cell; each one being connected 3-dimensionally with 12 other octahedra by shared edges. The Hf atoms (12d sites) were located in S octahedra. The Ag atoms were distributed over 3 different sites; with Ag1 in 8c positions and Ag2 and Ag3 in 2 general 24e positions; each of them being occupied with a statistical occupancy of 1/6. It was found that the material was a mixed conductor which exhibited a relatively high ionic conductivity. The compound became more conductive at temperatures above 137C, due to a transition from a low-temperature ordered phase to a high-temperature disordered one. The Ag+ conductivity attained a value of 0.0227S/cm at 198C.

O.Amiel, H.Wada: Journal of Solid State Chemistry, 1995, 115[1], 112-9