Structure characterization and ionic conductivity of Ag2VP2O8

This paper reports the structure, transport properties, and magnetic susceptibility of the new silver vanadium(IV) diphosphate Ag2VP2O8. The structure was refined from X-ray powder diffraction by the Rietveld method. This phase, isostructural to Na2VP2O8, crystallizes in the monoclinic space group P2(1)/c with the parameters a = 7.739 Angstrom, b = 13.611 Angstrom, c = 6.294 Angstrom, beta = 99.01 degrees, Z = 4, and V = 654.8 Angstrom(3). It consists of [VP2O8](infinity), layers, observed in many phosphorus compounds, parallel to the (010) plane interleaved with silver cations. The structure delimits rather large tunnels running along the [010] direction, where silver cations are located too. Electrical transport measurement has been carried out, by complex impedance, to determine the ionic conductivity of the compound and its evolution with temperature and frequency. Curie-type behavior is observed in the magnetic susceptibility which confirms the tetravalent state of vanadium and suggests no magnetic interactions. (C) 1997 Academic Press.