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High‐resolution Brillouin scattering and heat capacity studies of bis(guanidinium)zirconium bis(nitrilotriacetate)hydrate, [C(NH 2 ) 3 ] 2 Zr[N(CH 2 COO) 3 ] 2 ·H 2 O
Author(s) -
Mączka M.,
Kaminskii A. A.,
Hanuza J.,
Kojima S.
Publication year - 2009
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/jrs.2339
Subject(s) - brillouin scattering , hydrate , chemistry , heat capacity , brillouin zone , phase transition , raman scattering , zirconium , phase (matter) , raman spectroscopy , condensed matter physics , crystallography , thermodynamics , inorganic chemistry , optics , laser , physics , organic chemistry
High‐resolution micro‐Brillouin scattering and heat capacitiy studies of polar bis(guanidinium)zirconium bis(nitrilotriacetate)hydrate were performed in the temperature range 230–305 K. Strong anomalies in the Brillouin shift and the attenuation were observed near 290 K upon cooling for the sound waves corresponding to the c 22 elastic constant. For this elastic constant, the coupling between the order parameter and the elastic strains is linear quadratic. In case of the c 44 and c 66 , the coupling is biquadratic, giving rise to an increase of these parameters below 290 K. The analysis of the acoustic anomalies and heat capacity results near 290 K revealed that they correspond to a second‐order, cell‐multiplying, displacive phase transition. The second phase transition leads to weak acoustic anomalies at approximately 284 K. Copyright © 2009 John Wiley & Sons, Ltd.