CRYSTAL-STRUCTURE OF DECACALCIUM TETRAPOTASSIUM HEXAKIS(PYROPHOSPHATE) NONAHYDRATE

The crystal structure of Ca10K4(P2O7)(6) . 9H(2)O has been determined by single crystal X-ray diffraction. Crystals are hexagonal, space gro up P6(3)cm with a = 11.761(1), c = 9.770(1) Angstrom, and Z = 1. The s tructure was refined to R = 0.028 and R(w) = 0.037 for 468 reflections with I greater than or equal to 3 sigma(I). The structure consists of a compact assembly of Ca and P2O7 ions arranged in layers perpendicul ar to the c-axis in a hexagonal array with relatively large open chann els along the c-axis. The K ions and the water molecules are located i n these open channels and are disordered.