Thermodynamic properties in the clathrate-type silver- and copper-oxide: Ag6 O8MX and Cu6O8MX (M = cation, X = anion)

We present the thermodynamic properties in the clathrate-type silver- and copper-oxides Ag6O8MX and Cu6O8MX (M = cation, X = anion) compounds, having Ag6O8 (or Cu6O8)-cage in their crystal structure. Ag6O8MX and Cu6O8MX are crystallized in a cubic structure with a space group of Fm3-barm. We synthesized high quality samples of Ag6O8MX and Cu6O8MX and examined the electrical resistivity, magnetic susceptibility, and specific heat measurements. The superconductivity in Ag6O8AgX (X NO3- and HF2- have an isotropic gap symmetry by means of the specific heat data. In Cu6O8MCl, the ground sata of Cu6O8MCl compounds changed metallic to semiconducting by changing the valence state of M site ion.