Exploring the dielectric characteristics of NBT-MFO multiferroic nanocomposites for enhanced energy storage applications

Abstract

Multiferroic nanocomposites with the composition (1-x) Na_0⋅5Bi_0⋅5TiO₃ - (x) MgFe₂O₄, for x values of 0, 0.2, 0.5, 0.8, and 1.0, have been synthesized using the established solid-state reaction technique. A comprehensive dielectric analysis revealed significant enhancements in the dielectric properties of the nanocomposites compared to their single-phase counterparts. The relative permittivity (ε') and dielectric loss (ε'') both revealed behavior indicative of Maxwell-Wagner polarization, with pronounced dispersion observed at lower frequencies and higher temperatures. The multiferroic 0.50NBT-0.50MFO and 0.80NBT-0.20MFO nanocomposites displayed the highest dielectric constant, attributed to significant cationic disorder within the structure. The frequency-dependent capacitance and dielectric constant in the wet state revealed the promising potential of these nanocomposites for hydroelectric cell applications, due to increased lattice defects, porosity, oxygen vacancies, and unsaturated surface cations compared to single-phase NBT and MFO. The overlapping normalized impedance and modulus curve, converging onto a unified master curve, indicated temperature-invariant dynamic processes governing conduction and spatially confined relaxation. The Nyquist curves of impedance presented semicircular arcs that were suppressed, indicative of non-Debye relaxation, while the decrease in arc radii with rising temperature highlighted the semiconducting nature of the synthesized system. These findings underscore the potential of these nanocomposites for advanced applications in electronics and energy storage systems.