First-principles study of the mechanisms of the pressure-induced dielectric anomalies in ferroelectric perovskites

Abstract : The pressure-induced giant dielectric anomaly at 0 K of ABO3 perovskites is investigated at the Hartree-Fock, density-functional theory and hybrid levels. Its mechanism is analyzed in terms of thermodynamic phase stability, structural and phonon contributions and Born effective charges. It is shown that the IR-active soft phonon is responsible for the anomaly. This mode always involves a displacement and a deformation of the oxygen octahedra, while the roles of A and B ions vary among the materials and between high- and low-pressure phase transitions. A sharp increase in the phonon amplitude near the phase transition gives rise to the dielectric anomaly. The use of hybrid functionals is required for agreement with experimental data. The calculations show that the dielectric anomaly in the pressure-induced phase transitions of these perovskites is a property of the bulk material. © 2013 Taylor & Francis.
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Phase Transitions, 2013, 86 (11), pp.1069-1084. 〈10.1080/01411594.2012.754442〉
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Soumis le : mercredi 4 octobre 2017 - 19:06:31
Dernière modification le : jeudi 11 janvier 2018 - 06:28:13

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G. Sophia, P. Baranek, C. Sarrazin, Michel Rérat, R. Dovesi. First-principles study of the mechanisms of the pressure-induced dielectric anomalies in ferroelectric perovskites. Phase Transitions, 2013, 86 (11), pp.1069-1084. 〈10.1080/01411594.2012.754442〉. 〈hal-01610565〉

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