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arXiv · 1110.2992

Terahertz and Infrared Studies of Antiferroelectric Phase Transition in Multiferroic Bi_0.85Nd_0.15FeO_3

V. Goian·S. Kamba·S. Greicius·D. Nuzhnyy·S. Karimi·I. M. Reaney
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Abstract

High-frequency dielectric studies of Bi_0.85Nd_0.15FeO_3 ceramics performed betweeen 100 and 900 K reveal hardening of most polar phonons on cooling below antiferroelectric phase transition, which occurs near 600 K. Moreover, a strong THz dielectric relaxation is seen in paraelectric phase. Its relaxation frequency softens on cooling towards Tc ~ 600 K, its dielectric strength simultaneously decreases and finaly the relaxation disappears from the spectra below 450 K. Both phonon and dielectric relaxation behavior is responsible for a decrease in the dielectric permittivity at the antiferroelectric phase transition. Origin of unusual strong THz dielectric relaxation in paraelectric phase is discussed. Bi_0.85Nd_0.15FeO_3 structrure lies on the phase boundary between polar rhombohedral and non-polar orthorhombic phase and owing to this the polarization rotation and polarization extension can enhance the piezoelectric response of this system. Similarities and discrepancies with lead-based piezoelectric perovskites, exhibiting morphotrophic phase boundary between two ferroelectric phases, are discussed.

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V. Goian, S. Kamba, S. Greicius, D. Nuzhnyy, S. Karimi, I. M. Reaney. 2011-10-13. Terahertz and Infrared Studies of Antiferroelectric Phase Transition in Multiferroic Bi_0.85Nd_0.15FeO_3. https://doi.org/10.1063/1.3650241

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