Complex Three-Dimensional [Au3In5] Polyanions in Ln2Au3In5 (Ln=Ce, Pr, Nd, Sm)

The silica gel containing molybdotungstovanadogermanic acid was prepared by means of the sol–gel method. SEM and infrared spectra revealed that the Keggin structure characteristic of the GeW9Mo2VO5-40 anion was presented in the silica gel skeleton. The regularity of the change of characteristic peaks in the infrared spectra was investigated. The XRD pattern of the gel was amorphous. The TG curve showed three steps of weight loss. The DTA curve showed that the thermal stability of the gel is lower than that of the pure molybdotungstovanadogermanic acid. The gel exhibited considerably high proton conductivity, which increased with the increase of the molybdotungstovanadogermanic acid content. The proton conductivity of the gel containing 71 wt% molybdotungstovanadogermanic acid is 1.86×10-3 S cm-1at 18°C.