HYDROTHERMAL SYNTHESIS AND STRUCTURES OF 2 LAYERED DIOXOVANADIUM(V) PHOSPHATES A(VO2)PO4 (A = BA, SR)

Barium dioxovanadium(V) phosphate, Ba(VO2)PO4, M(r) = 315.256, monoclinic, P2(1)/c, a = 5.616 (2), b = 10.062 (1), c = 8.727 (1) angstrom, beta = 90.90 (2)-degrees, V = 493.1 (2) angstrom 3, Z = 4, D(x) = 4.247 g cm-3, lambda(Mo K-alpha) = 0.70930 angstrom, mu = 100.49 cm-1, F(000) = 568, T = 297 K, R = 0.0239 for 2025 unique reflections. Strontium dioxovanadium(V) phosphate, Sr(VO2)PO4, M(r) = 265.536, monoclinic, P2(1)/c, a = 5.430 (1), b = 9.846 (2), c = 8.517 (2) angstrom, beta = 90.60 (2)-degrees, V = 455.3 (2) angstrom 3, Z = 4, D(x) = 3.873 g cm-3, lambda(Mo K-alpha) = 0.71073 angstrom, mu = 136.45 cm-1, F(000) = 496, T = 297 K, R = 0.0288 for 844 unique reflections. Single crystals of the title compounds were grown hydrothermally at 503 K. Their structures contain layers of phosphate tetrahedra and edge-sharing bioctahedra, that contain two distorted VO6 octahedra, with the divalent metal cations between the layers. Within a layer windows are formed by the edges of four octahedra and four tetrahedra.