Impedance spectroscopy and permittivity study of (1-x)NBT-xBT ceramics

Abstract

The complex impedance spectroscopy method was applied to evaluate the profound characteristics of the electrical transport capacity of lead-free ferroelectric ceramic solid solutions of (1-x) (Na0.5Bi0.5)TiO₃-xBa TiO₃ (NBT-xBT) (0.00 ≤ x ≤ 0.10). The elaboration of NBT-xBT, via a solid-state reaction between (Na0.5Bi0.5)TiO₃ and BaTiO₃, was determined using X-ray diffraction. Refinements, at room temperature, identified a rhombohedral phase, space group R3c for x=0.0 and 0.03, which possesses an antiphase, corresponding to the tilting system ā ā ā with an angle of inclination of 8.24° according to Glazers notation. We used the complex impedance, complex electric Cole-Cole diagram and frequency-dependent AC conductivity analysis to examine the relaxation and conduction mechanism in these samples, which exhibit non-Debye type behaviour. In addition, using an equivalent circuit composed of resistance and capacitance, we examined the different contributions (grains and grain boundaries) in our samples. (Na0.5Bi0.5)TiO₃ exhibits a dielectric resonance, which manifests itself as negative permittivity. The resonance development of NBT-xBT in the range (500Hz-2MHz) is discussed in this paper.

Keywords

• (1-x)(na0.5bi0.5)tio₃-xbatio₃
• solid-state method
• rietveld refinement
• complex impedance
• cole-cole diagram