Open AccessOrder–disorder transition in monoclinic sulfur: a precise structural study by high‐resolution neutron powder diffraction
Author(s) -
David W. I. F.,
Cox S. F. J.,
Wood P. T.,
Ibberson R. M.
Publication year - 2006
Publication title -
acta crystallographica section b
Language(s) - English
Resource type - Journals
eISSN - 1600-5740
pISSN - 0108-7681
DOI - 10.1107/s0108768106039309
Subject(s) - monoclinic crystal system , neutron diffraction , materials science , critical exponent , diffraction , resolution (logic) , powder diffraction , crystallography , order (exchange) , high resolution , phase transition , first order , sulfur , condensed matter physics , chemistry , crystal structure , physics , optics , mathematics , geology , finance , artificial intelligence , computer science , economics , metallurgy , remote sensing
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, T c = 198.4 (3) K, and a critical exponent, β = 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.