Impedance spectroscopy of (Na0.5Bi0.5)(Zr0.25Ti0.75)O3 lead-free ceramic

Polycrystalline sample of (Na0.5Bi0.5)(Zr0.25Ti0.75)O3 was prepared using a high-temperature solid-state reaction technique. XRD analysis indicated the formation of a single-phase orthorhombic structure. AC impedance plots were used as tool to analyse the electrical behaviour of the sample as a function of frequency at different temperature. The AC impedance studies revealed the presence of grain boundary effect, from 350 °C onward. Complex impedance analysis indicated non-Debye type dielectric relaxation. The Nyquist plot showed the negative temperature coefficient of resistance (NTCR) character of (Na0.5Bi0.5)(Zr0.25Ti0.75)O3. AC conductivity data were used to evaluate the density of states at Fermi level and activation energy of the compound. DC electrical and thermal conductivities of grain and grain boundary have been assessed.