Abstract
THE existence of two forms of calcium sulphate hemihydrate, α and β, has not been firmly established. Slight differences in densities1, heats of formations2, and differential thermograms3 have been cited as evidence for the existence of the two forms. Morris4 observed a slight difference in the X-ray powder diffraction patterns of the supposed α and β forms, which has been attributed to stacking fault crystal imperfections4 and the intergrowth of a sub-structure of a lower symmetry5. The crystal structures of the two forms, however, have not been unequivocally determined6,7. This article reports infrared spectroscopic measurements, undertaken in the expectation that this would be a sensitive probe in ascertaining if two forms of calcium sulphate hemihydrate actually exist. In the few previously reported infrared studies of calcium sulphate hemihydrate8–10 no attempt was made to differentiate between the two supposed forms.
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CLIFTON, J. Infrared Spectra of Supposed α and β Forms of Calcium Sulphate Hemihydrate. Nature Physical Science 232, 125–126 (1971). https://doi.org/10.1038/physci232125a0
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DOI: https://doi.org/10.1038/physci232125a0
