Origin of low-frequency dielectric permittivity in BiFeO3 multiferroic ceramics

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A one-dimensional conductivity barrier model is introduced to describe the dielectric response and conductivity of BiFeO 3 (BFO) and (Bi 0.95 Nd 0.05 )FeO 3 (BFO-5%Nd) ceramics as functions of temperature and frequency. Good qualitative fits of conductivity and dielectric permittivity in the intermediate-temperature region (500-800 K) are obtained with intrinsic barriers of B=8700 K (for BFO) and B=8400 K (for BFO-5%Nd), and extrinsic barriers of Δ=2500 K (for BFO and BFO-5%Nd). The phase-shifted conductivity is responsible for a step-like dielectric relaxation in the region of 500-800 K. The experimental conductivity departs from the conductivity-barrier-model fit below 650 K. This deviation is likely caused by the magneto-electric coupling near the antiferromagnetic-paramagnetic transition. This work suggests that the 5% mole Nd-substitution can stabilize the perovskite structure in BFO ceramic.




C.-S. Tu, T.-H. Wang, V.H. Schmidt, and R.R. Chien, “Origin of low-frequency dielectric permittivity in BiFeO3 multiferroic ceramics,” IEEE Conference Publication for ISAF/PFM 2011 International Symposium on Applied of Ferroelectrics, Vancouver, BC, pp. 24-27 (2011). doi: 10.1109/ISAF.2011.6014103.
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