Abstract
In the present study, the electrical properties of BiFeO3 ceramic specimens prepared by solid-state sintering method by using two thermal treatment strategies are comparatively investigated. The room temperature XRD pattern shows perovskite single-phase, in the limit of XRD accuracy, for BiFeO3 ceramic prepared by single-step method. For two-step sintering method sample small amounts of secondary Bi2Fe4O9 phases were identified. The ceramics show a non-homogeneous microstructure, consisting of ceramic grains with irregular morphology and interconnected porosity mainly in the grain boundary regions in the case of two-step sintering sample. The most interesting feature is the conduction anomaly observed on the conductivity in the low-frequency range close to dc-conductivity. The Arrhenius plot of the dc-conductivity determined at the lowest frequency vs. 1/T shows two distinct linear regions separated by the mentioned temperature range of (189–244) K, for which the dc conductivity could not be determined from the present impedance spectroscopy data only. It is clear that in the mentioned temperature range (for both samples), a conduction anomaly takes place.
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•BiFeO3 ceramics prepared by two thermal treatments are comparatively investigated.•It was demonstrated that the dc-conductivity is a thermally-activated process.•A conductivity anomaly takes place in the range of (189–244) K for both samples.•This type of transitions is intrinsic in BiFeO3 and is not due to secondary phases.