https://doi.org/10.1140/epjb/s10051-026-01191-6
Research - Statistical and Nonlinear Physics
Calculation of the T–n (n-carbon) phase diagram for the thienyl derivatives (PIR4 + PIR5) by the Landau phenomenological model
1
Department of Computer Engineering, Baskent University, 06790, Ankara, Turkey
2
Department of Electrical and Electronics Engineering, Istanbul Arel University, 34537, Büyükçekmece, Istanbul, Turkey
a
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Received:
17
January
2026
Accepted:
18
May
2026
Published online:
18
June
2026
Abstract
This study gives the calculation of the T–n phase diagram for the smectic–hexatic phase transitions in the binary mixture PIR4 + PIR5. By expanding the free energy in terms of the order parameters of the phases considered with the biquadratic coupling in the Landau phenomenological model, the phase line equations are obtained and they are fitted to the observed data in the literature. The Landau coefficients in the free energy expansion are associated with the temperature and concentration (C atoms) for the first-order transitions with the two triple points in this binary mixture. Our results indicate that the Landau model can explain the observed T–n phase diagram adequately and can be applied to some other binary mixtures.
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© The Author(s), under exclusive licence to EDP Sciences, SIF and Springer-Verlag GmbH Germany, part of Springer Nature 2026
Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.
