Investigation of conduction mechanisms and permittivity–conductivity correlation in a Gd-based perovskite structure

Abstract

Currently, the development of perovskites has required a lot of attention for fundamental investigation and electronic devices. The present study reported the electrical conductivity and the dielectric properties of a GdCa₂Cu₃O_δ (GdCaCuO) system prepared via the solid-state reaction method. The X-ray diffraction results indicate that GdCaCuO crystallizes in the tetragonal perovskite structure. The studied compound reveals elevated dielectric permittivity and significant electrical phenomena including the influence of multiple conduction and relaxation mechanisms on the transport of charges. From the impedance results, it is observed that the electrical and dielectric properties of the studied compound are governed by the contribution of the grain and the grain boundary regions. The Nyquist results and the blocking factor (α_R) were used to confirm the aforementioned properties. From the modulus results, we confirm again the presence of multiple relaxation processes and various types of polarization effects. The semiconductor character of the GdCaCuO ceramic is due to the activation of hopping conduction processes within the DC regime. Consequently, both the variable range hopping and the small polaron hopping models are used at low- and high-temperature ranges, respectively. At various temperatures, the conductivity spectra of the GdCaCuO ceramic conform to the double Jonscher power law. The power law behavior is attributed to the activation of hopping and tunneling conduction mechanisms. The presence of large dielectric dispersion in GdCaCuO is observed at low temperatures and decreases rapidly against increasing temperatures.