Enhanced dielectric and electrical properties of Li-doped BNBT ceramics for energy storage applications

The compound [(Bi0.5Na0.5)0.94Ba0.06]1-xLixTiO3 (BNBT-Li) 0 ≤ x ≤ 0.04), was prepared using a solid-state reaction method. In the X-ray diffraction (XRD) study, a tetragonal structure was observed for the compositions x = 0 and steadily modified to a cubic structure with further doping of Li contents. Rietveld analyses of samples displayed a tetragonal P4mm phase for pure and a cubic Pm $$3$$ m phase for Li-doped BNBT ceramics. Scanning Electron Microscopy (SEM) images revealed a uniform and smooth grain structure throughout the compositions, and the grain size was reduced with the Li contents. Elements such as oxygen (O), sodium (Na), carbon (C), titanium (Ti), aluminum (Al), bismuth (Bi), and barium (Ba) present in the compound were confirmed by Energy Dispersive X-ray (EDX). The maximum dielectric constant temperature (Tm) was enhanced from 260 °C (x = 0) to 275 °C (x = 0.04), and the peaks at Tm became broader and shifted to the higher temperature side upon increasing frequency and Li. The diffusivity (γ) values, ranging from 1 < γ < 2, indicate a deviation from the Curie–Weiss Law. Li additions enhanced the diffuse phase transition and relaxor-like ferroelectric nature. The low-temperature conductivity showed a moderate temperature dependence, and the AC conductivity was higher for x = 0 and decreased for further ratios. In the Cole–Cole plot, a single semicircle appeared, and the arc's depression was increased with temperature, suggesting the main contributions from grain boundaries and the bulk grain. These properties suggest that the BNBT-Li compound has potential applications in modern piezoelectric actuators and dielectric capacitors.