Two New Titanium Pyroarsenates: Alpha-TiAs2O7 and Beta-TiAs2O7

摘要

Two new titanium pyroarsenate phases, alpha-TiAS2O7 and beta-TiAS2O7, have beenprepared by high temperature hydrothermal methods and characterized by single crystal x-ray diffraction techniques. Both structures are based on different three-dimensional networks of vertex-sharing TiO6 octahedra and AsO4 tetrahedra. The TiO6 groups show little distortion from regular octahedral geometry, and the arsenate anions are linked in pairs via As-O-As bonds to form pyroarsenate (AS2O7) groups. Alpha-TiAS2O7 is isostructural with a polymorph of SiP2O7; beta-TiAS207 is a new structure.