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

Abstract

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.