Dielectric characterization of bismuth layered (Bi2O3)(NaxFe1−xO3) ceramics

Abstract

Bismuth layered (Bi2O3)(NaxFe1−xO3) (0.2≤x≤0.8) ceramics have been prepared by the conventional solid-state reaction method. Powder XRD analysis reveals the polycrystalline structure of the samples. Dielectric properties, viz. dielectric constant, dielectric loss and ac electrical conductivity of the ceramics sintered at various temperatures have been studied in the frequency range 10−1–107Hz. The frequency and temperature dependent conductivity investigations have been carried out by using impedance spectroscopy. It was observed that the samples exhibit bulk conduction which increases with increase in temperature and with the increase in Na+ ion concentration. The conductivity mechanism at room temperature shows a frequency dependence which can be ascribed to the presence of oxygen vacancies. Combined impedance and modulus plots were used to analyze the sample behavior as a function of frequency and temperature. The effect of temperature on the scaling of dielectric modulus indicates that the conductivity relaxation mechanism is temperature independent. The overlapping of the normalized peaks corresponding to impedance and electrical modulus suggests the single mechanism for the dynamic processes occurring in the present ceramics. The dielectric and conductivity properties of the studied ferroelectric ceramics make it a promising material for fatigue resistance in device applications. Scanning electron microscope (SEM) and energy dispersive X-ray analysis (EDX) confirms the formation of solid solution of BNFO ceramic as major phase.