CRYSTAL-STRUCTURE DETERMINATION OF THE HYDRATED GALLIUM PHOSPHATE GAPO4-CENTER-DOT-2H(2)O, ANALOG OF VARISCITE

The crystal structure of the hydrated gallium phosphate, GaPO4. 2H(2)O , analog of variscite, has been determined by means of single-crystal X-ray diffraction characterisation. The structure is built from the co nnection of PO4 tetrahedra with GaO4(H2O)(2) octahedra. The 3D framewo rk consists of the stacking of 6(3) nets and is related to the topolog ies of metavariscite, the polymorphs of silica (tridymite, cristobalit e) and zeolite Li-A(BW). A formation pathway of the hydrated gallium p hosphate with leucophosphite structural type is proposed from that of the variscite one. Crystal data: Mr = 200.72 g mol(-1), orthorhombic, space group Pbca (no. 61), a = 9.9260(1) Angstrom, b = 8.6189(1) Angst rom, c = 9.7622(1) Angstrom, V = 835.17(2) Angstrom(3), Z = 8, R1(F) = 0.0361, wR2(F-2) = 0.0922 for 1255 reflections with I > 2 sigma(I). ( C) Academie des sciences/Elsevier, Paris.