Hydrothermal synthesis, crystal structure and ionic conductivity of Ag2VO2PO4: a new layered phosphate of vanadium(V)

A new dioxovanadium(V) phosphate, Ag2VO2PO4, has been synthesised hydrothermally at 230 °C and characterized by single-crystal X-ray diffraction. The compound crystallizes in the monoclinic space group C2/m with a= 12.431(3), b= 6.298(1), c= 6.300(2)Å, β= 90.38(2)°, Z= 4 and R= 0.026. The structure consists of layers of dimers of edge-sharing VO6 octahedra and PO4 tetrahedra, extending parallel to the (001) crystallographic plane with silver ions between the layers. The structural relationship with BaVO2PO4 is discussed. Alternating current impedance measurements on Ag2VO2PO4 indicate that the ionic conductivity at 375 °C is 1 × 10–4Ω–1 cm–1 with an activation energy of 47 kJ mol–1.