X-RAY-POWDER DIFFRACTION STUDY OF LAYER COMPOUNDS - THE CRYSTAL-STRUCTURE OF ALPHA-TI(HPO4)2.H2O AND A PROPOSED STRUCTURE FOR GAMMA-TI(H2PO4)(PO4).2H2O

Alpha-Ti(HPO4).H2O was investigated by X-ray powder diffraction methods. A profile least-squares analysis of the X-ray data proved the substance to be isostructural with alpha-Zr(HPO4)2.H2O. The lattice parameters are a = 8.630(2), b = 5.006(1), c = 16.189(3) angstrom, beta = 110.20(1)-degrees, Z = 4, space group P2(1)/c (No. 14). The basic features of the structure of gamma-TiH2P2O8.2H2O were found by a combination of direct methods and packing considerations. A partial model was refined. The model is in accordance with NMR results and shows that the compound shall be formulated Ti(H2PO4)(PO4).2H2O. The lattice parameters for the partial model are a = 5.181(1), b = 6.347(1), c = 11.881(1) angstrom, beta = 102.59(1)-degrees, Z = 2, space group P2(1) (No. 4).