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

The pressure-induced giant dielectric anomaly at 0 K of ABO 3 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...

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Bibliographic Details
Published in:Phase transitions 2013-11, Vol.86 (11), p.1069-1084
Main Authors: Sophia, Gustavo, Baranek, Philippe, Sarrazin, Christian, Rérat, Michel, Dovesi, Roberto
Format: Article
Language:English
Subjects:
Anomalies
Chemical Sciences
Deformation
DFT
dielectric anomaly
Dielectrics
ferroelectricity
Hartree-Fock
hybrid functionals
Materials science
or physical chemistry
Perovskite
Phase transitions
Pressure
Theoretical and
Thermodynamics
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Summary:The pressure-induced giant dielectric anomaly at 0 K of ABO 3 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.
ISSN:0141-1594
1029-0338
DOI:10.1080/01411594.2012.754442