Neutron Diffraction Study of Gypsum, CaSO42H2O

Using neutron diffraction data, the crystal structure of gypsum has been refined by Fourier and least squares methods. The hydrogen bond distance was found to be 2.82 A rather than 2.71 A, reported previously. The hydrogen positions are consistent with those obtained from nuclear magnetic resonance. The O–H distance is 0.99±0.03 A, and it appears that the O, H, O atoms are collinear. Infrared and Raman results are discussed in terms of the refined structure.