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Structural Phase Transitions and Vibrational Study of CsH(SO 4 ) 0.76 (SeO 4 ) 0.24
Author(s) -
Gargouri M.,
Mhiri T.,
Daoud A.,
Jouini T.
Publication year - 1997
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/1521-3951(199703)200:1<3::aid-pssb3>3.0.co;2-z
Subject(s) - selenate , hydrogen bond , crystallography , chemistry , hydrogen , phase (matter) , phase transition , crystal structure , molecule , selenium , thermodynamics , organic chemistry , physics
CsH(SO 4 ) 0.76 (SeO 4 ) 0.24 , M m = 241.2, single crystals were grown and appear to be isomorphous with CsHSeO 4 . The space group is P2 1 /a, the lattice constants are: a = 7.8340(10) Å, b = 8.2147(6) Å, c = 7.4440(10) Å, β = 110.910(10)°, V = 447.50(9) Å 3 , Z = 4, D x = 3.582 Mg m −3 , λ(MoK α ) = 0.71069 Å, μ(MoK α ) = 10.269 mm −1 . F (000) = 818, T = 293(2) K (room temperature phase), R = 0.023 and w R = 0.0563 for 883 observed reflections. The hydrogen sulphate or hydrogen selenate groups are connected by hydrogen bonds. The separated chains of asymmetric hydrogen bonds run parallel to the c ‐axis. The O–H … O distance utilized in the hydrogen bonding is 2.608 Å which is 2.603 Å for CsHSeO 4 . Mixed cesium hydrogen sulphate selenate CsH(SO 4 ) 0.76 (SeO 4 ) 0.24 undergoes two phase transitions at T = 333 and 408 K. The values of the enthalpies are 2.02 and 4.37 kJ/mol, respectively.