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Ordering of Protons at the Phase Transition in Superionic Crystals of CsHSO 4 Type
Author(s) -
Dzhavadov N. A.,
Rustamov K. A.
Publication year - 1992
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.2221700107
Subject(s) - brillouin zone , proton , wave vector , phase transition , phonon , tetrahedron , condensed matter physics , observable , physics , jump , chemistry , crystallography , atomic physics , quantum mechanics
The phase transition (PT) D 4h 19→ C 2h 5in CsH(D)SO 4 ‐type crystals by one wave vector of the star { k 13 } (X‐point of the Brillouin zone (BZ)) and of the wave vector { k 14 = 0} (Γ‐point of BZ) is considered. A symmetry analysis of proton ordering at the PT is performed with account of proton–phonon interaction. The method of concentration waves is applied. The expression for the average occupation number of proton positions is obtained. The experimentally observable ordering of protons and the dynamics of SO 4 tetrahedra at the PT is described. The entropy jump at the PT is calculated. The obtained theoretical results are in good agreement with experiment.