Room Temperature Impedance Properties of BFO Ceramics

This study investigates the room temperature impedance properties of Bismuth Ferrite (BiFeO3) ceramics synthesized via the Polyvinyl Alcohol (PVA) Sol-Gel method. The structural analysis using X-ray diffraction (XRD) confirms the formation of a phase-pure BiFeO3 structure with a rhombohedral R3c space group, exhibiting no secondary phases at an optimized sintering temperature of 870 °C. Impedance spectroscopy measurements, conducted over a frequency range of 1 Hz to 1 MHz, reveal a strong frequency-dependent behavior in both the real (Z′) and imaginary (Z″) components of impedance. At low frequencies, high impedance values indicate the dominance of grain boundary resistance, whereas at higher frequencies, bulk-controlled conduction prevails. The presence of a relaxation peak in the imaginary impedance spectrum suggests a dielectric relaxation phenomenon. The AC conductivity (σ′ac) exhibits a characteristic frequency-dependent increase, following Johnscher's power law, with a transition from grain boundary-dominated resistance to a bulk-dominated conduction mechanism. Additionally, space charge polarization contributes to the impedance behavior at lower frequencies. These results highlight the potential of BiFeO3 ceramics for use in frequency-sensitive applications, including capacitors, sensors, and multiferroic devices.