No abstract

Crystal Structure and Orbital-Singlet State of Ag xVP2O7. -Polycrystalline samples of Ag xVP2O7 (0.7  x  0.9) are prepared by solid state reaction of mixtures of composition 2xAg 3PO4, 4xVPO4, 3(1-x)VPO5, and (3-x)V(PO3)3 (sealed quartz tubes, 1073 K, 12 h). Single crystals of AgVP2O7 (x = 1) are prepared at 1323 K for 72 h. AgVP 2O7 crystallizes in the monoclinic space group P21/c with Z = 4 (single crystal XRD). The structure contains VO 6 octahedra which are bridged by P2O7 groups to form a three-dimensional network with hexagonal tunnels in which a pair of Ag ions is located. The samples are further characterized by measurements of the electrical resistivities and magnetic susceptibilities. The materials exhibit a singlet ground state electron configuration with a gap in the order of 10 K to the doublet state. The title system is expected to show a high voltage when applied as a positive electrode for lithium ion batteries. -(ONODA*, M.; SAKAMOTO, T.; J. Solid State Chem. 220 (2014) 132-136, http://dx.