Acta Crystallographica Section B

Structural Science

Volume 52, Part 5 (October 1996)

short communications

Acta Cryst. (1996). B52, 896-898 [ doi:10.1107/S0108768196006702 ]

Neutron powder diffraction study of -Ti(HPO₄)₂.H₂O and -Hf(HPO₄)₂.H₂O; H-atom positions

M. A. Salvadó, P. Pertierra, S. García-Granda, J. R. García, J. Rodríguez and M. T. Fernández-Díaz

Abstract: The complete crystal structures, including H-atom positions, of [alpha] -Ti(HPO₄)₂.H₂O ( [alpha] -TiP) and [alpha] -Hf(HPO₄)₂.H₂O ( [alpha] HfP) were determined by Rietveld refinement and Fourier synthesis, using constant-wavelength neutron diffraction data. This work is one of few recent examples of the determination of H atoms using neutron powder diffraction with an intense source. The orientation of water molecules in the cavities of [alpha] -TiP is similar to that previously found for [alpha] -ZrP. For [alpha] -HfP, although the hydrogen-bonding scheme is identical, the orientation of water molecules in similar cavities was found to be different.