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X‐ray studies of the low‐temperature phase of K 2 SO 4
Author(s) -
Ahmed S. A.
Publication year - 1996
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/pssb.2221950112
Subject(s) - orthorhombic crystal system , monoclinic crystal system , phase transition , crystallography , crystal structure , crystallite , lattice (music) , diffraction , phase (matter) , x ray crystallography , materials science , chemistry , condensed matter physics , physics , optics , organic chemistry , acoustics
The low‐temperature phase transition of potassium sulphate (K 2 SO 4 ) has been investigated by X‐ray diffraction measurements on polycrystalline material. From the temperature dependence of the lattice parameters it was confirmed that K 2 SO 4 crystals undergo a structural phase transition of second‐order type at 56 K. Above the transition point (β‐phase) the K 2 SO 4 crystal belongs to the Pnam (D 2h 16 ) orthorhombic space group with lattice parameters a = 0.74780 nm, b = 1.00707 nm, and c = 0.57701 nm at 293 K. The crystal symmetry of the low‐temperature phase (below 56 K, γ‐phase) is probably monoclinic with space group P2 1 /n11 (C 2h 5 ). The low‐temperature phase transformation is thought to be of displacive type.