A. Meresse, P. Loyzance, N. Chanh
1983
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0
Influential Citations
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Journal
Journal of Physics and Chemistry of Solids
Abstract
Abstract The use of various techniques such as X-ray and neutron diffraction, Raman scattering, diffusion and calorimetry has allowed us to characterize the polymorphic behaviour of 2-fluoronaphthalene. Under atmospheric pressure, three crystalline forms can be detected between 80 K and the melting temperature. The high temperature one, F I , which is stable from 272 K to the melting point, is isomorphous with naphthalene (space group P 2 1 / a,Z = 2); by cooling it can be preserved as a metastable form down to 154 K, the 272-154 K range being the stability domain of the form F III . Below 154 K, a new form, called F III appears. The kinetics of the transformation F I → F III seem to be dependent upon the size of the crystals. The Raman spectra of f I and F III are identical, which suggests similar structural disorder in both phases. This is also supported by the low value of the entropy associated with the transition F III → F I (0.55 J K −1 mole −1 ). The unit cell parameters of the F III and F III forms have been determined from data using automatic indexing methods. The two solid-solid transitions are first order, the F III – F III' one being “explosive”.