Influence of B-site zr ion substitution on the structural, dielectric and ferroelectric properties in Bi0.5Na0.5TiO3-based lead-free ceramics

Study of the B-site Zr4+ ions substitution in Bi0.5Na0.5Ti1−xZrxO3 (0.0 ≤ x ≤ 0.075) ceramics obtained by the solid-state reaction method is presented. All the ceramics shows single-phase rhombohedral structure (with R3c space group) that is confirmed by the room temperature X-ray diffraction (XRD) data. A very small amount of extra phase of Bi2Ti2O7 is seen in all the samples. An apparent shift is noted in Bragg positions towards the higher 2θ side for B-site Zr4+ ion substituted BNTZO (7.5%) ceramic. The Raman scattering measurement determines even Raman-active modes. The dielectric constant (ε′) and loss (tanδ) for all the ceramics are obtained at room temperature that shows nonlinear behaviour with increasing Zr4+ ion concentration. The maximum value of (ε′) ~ 2883 is observed at low frequency for BNTZO 7.5% ceramic. The room temperature ac conductivity is observed to increase with rise in frequency. The electric response of impedance spectroscopy confirms the effect of grains and grain boundaries. The ferroelectric hysteresis loop illustrates the ferroelectric properties and leakage current for all ceramics due to the conducting nature of samples.