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A Thermodynamic Theory of the Improper Antiferroelectric Phase Transition in ADP
Author(s) -
Konwent H.,
Lorenc J.
Publication year - 1978
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.2220880242
Subject(s) - landau theory , phase transition , thermodynamics , dielectric , thermodynamic potential , maxima and minima , consistency (knowledge bases) , materials science , basis (linear algebra) , parameter space , condensed matter physics , statistical physics , physics , mathematics , quantum mechanics , mathematical analysis , geometry , statistics
Abstract The thermodynamic theory of the elastic and dielectric properties of ammonium dihydrogen phosphate is developed on the basis of the improper phase transition. By the representation analysis the transformation properties of the two‐component order parameter are investigated and the thermodynamic potential of the Landau type describing both elastic and dielectric properties (triggered by the order parameter) is derived, which correctly describes the space group symmetry change at the transition point. Its minima and their stability conditions are also studied. The temperature dependence of the spontaneous deformations and material constants is analysed in detail and consistency with the available experimental data is briefly discussed.