Order-disorder transition in monoclinic sulfur: a precise structural study by high-resolution neutron powder diffraction.
High-resolution neutron powder diffraction has been used in order to characterize the order-disorder transition in monoclinic cyclo-octasulphur. Rapid data collection and the novel use of geometrically constrained refinements has enabled a direct and precise determination of the order parameter, based on molecular site occupancies, to be made. The transition is critical and continuous; with a transition temperature, Tc=198.4 (3) K, and a critical exponent, beta=0.28 (3), which is indicative of three-dimensional ordering. Difficulties encountered as a consequence of the low thermal conductivity of the sample are discussed.
David
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ISIS Facility, CCLRC, Rutherford Appleton Laboratory, Chilton, Didcot, Oxfordshire OX11 0QX, England.
Ibberson
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Cox
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Wood
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D008958:Models, Molecular; D033363:Neutron Diffraction; D033362:Powder Diffraction; D012680:Sensitivity and Specificity; D013455:Sulfur / Q000737:chemistry*; D013696:Temperature
D013455:Sulfur