Premium
Raman scattering investigation of order–disorder phase transitions in cadmium tris(thiourea) sulphate (CTS)
Author(s) -
Oussaïd M.,
Becker P.,
CarabatosNédelec C.
Publication year - 2000
Publication title -
journal of raman spectroscopy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.748
H-Index - 110
eISSN - 1097-4555
pISSN - 0377-0486
DOI - 10.1002/1097-4555(200006)31:6<529::aid-jrs572>3.0.co;2-9
Subject(s) - thiourea , raman spectroscopy , raman scattering , phase transition , wavenumber , chemistry , analytical chemistry (journal) , cadmium , spectral line , phase (matter) , condensed matter physics , optics , physics , organic chemistry , astronomy
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.