Raman scattering investigation of order-disorder phase transitions in cadmium tris(thiourea) sulphate (CTS)

The Raman spectra of cadmium tris(thiourea) sulphate (CTS) single crystals were studied in the wavenumber range from 400 to 650 cm−1 for temperatures between 10 and 300 K. Two phase transitions occurring at 55 ± 2 and 134 ± 2 K were observed and characterized. Based on the evolutions of the spectral...

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Bibliographic Details
Published in:Journal of Raman spectroscopy 2000-06, Vol.31 (6), p.529-533
Main Authors: Oussaïd, M., Becker, P., Carabatos-Nédelec, C.
Format: Article
Language:English
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Summary:The Raman spectra of cadmium tris(thiourea) sulphate (CTS) single crystals were studied in the wavenumber range from 400 to 650 cm−1 for temperatures between 10 and 300 K. Two phase transitions occurring at 55 ± 2 and 134 ± 2 K were observed and characterized. Based on the evolutions of the spectral parameters (wavenumber, damping and intensity) of the thermosensitive band appearing at 526 cm−1 in the spectra at 10 K, the transitions were found to be of an order–disorder nature. The values of the estimated critical exponents are 2β = 0.62, δ = 0.92 for the transition at 55 K and 2β = 1.04, δ = 0.77 for the transition at 134 K. The mechanism of transition appears to be closely related to the behaviour of the thiourea molecule. Copyright © 2000 John Wiley & Sons, Ltd.
ISSN:0377-0486
1097-4555
DOI:10.1002/1097-4555(200006)31:6<529::AID-JRS572>3.0.CO;2-9