Abstract
The isotypic borophosphates Na1.89Ag0.11[BP2O7(OH)] and Na-2[BP2O7(OH)]
were grown under mild hydrothermal conditions (T = 165-170 degrees C).
The crystal structures were solved by single crystal methods in the case
of Na1.89Ag0.11[BP2O7(OH)] and by refinement of powder data (Rietveld
method) for Na-2[BP2O7(OH)], respectively (orthorhombic, Pna2(1) (No.
33); a = 683.98(14)/682.36(1) pm, b = 2086.5(4)/2079.11 (4) pm, c =
1318.9(3)/1314.46(3) pm; Z = 12). The compounds contain a complex
two-dimensional structure consisting of layered tetrahedral blocks,
which are formed by six- and eight-membered rings of tetrahedra. The
Na+/Ag+-ions are located inside and near the surface of the 'layer
blocks' and are five-, six- and sevenfold coordinated by oxygen.