Exploration of the charge transport mechanism, complex impedance, dielectric/electric modulus and energy storage characteristics of the aloe vera (Aloe Barbadensis Miller) plant

Abstract

Complex impedance spectra at room temperature in the frequency range of 8 Hz—5 MHz were measured on freshly cut leaf sections of the Aloe vera plant by AC impedance spectroscopy. They were analyzed using a classical ‘brickwork’ equivalent circuit composed of grain and grain boundary contributions commonly applied to solid-state materials. The obtained grain resistance/capacitance was 0.4 MΩ/72 pF and grain boundary resistance/ capacitance was 66.4 MΩ/50 nF. The determined conductivity changed according to the Jonscher power law with σ_DC of 4.02 · 10^–5 (Ωm)⁻¹ and frequency constant of 0.92 characteristic for hopping as the conduction mechanism. Analysis of dielectric permittivity and electric modulus confirmed the non-Debye relaxation behavior. Nyquist plots for electric modulus revealed conductivity relaxation in the low frequency attributed to grain boundaries and impedance modulus displayed dielectric relaxation in the high frequency region associated with grains. A correlation has been established among the investigated parameters, morphology, and EIS-derived simulated parameters.