Electrical Conduction Mechanisms in Gd-Substituted WO₃ Ceramics: Experimental and Theoretical Approaches

Abstract

W 1−x Gd x O 3 ceramics with (x = 0, 0.02, 0.05, and 0.10) were synthesized via a facile hydrothermal route. The XRD and Raman spectra revealed the monoclinic phase (most stable) formation and successful incorporation of Gd ions into the WO 3 lattice. The scanning electron microscopy images displayed the presence of densely arranged grains with clearly visible grain boundaries. The EDX spectra show that the components are present in the desired stochiometric ratios. This study aims to elucidate the impact of doping of gadolinium over a wide range of frequencies and temperatures on the electrical properties and explore its potential practical applications. A notable shift from nearly constant loss (NCL) to superlinear-power law (SPL) behavior at 373 K is observed, further validated by the dielectric loss spectra. The trends in the frequency exponent indicate that the mechanism of charge transfer follows the quantum mechanical tunneling (QMT) and nonoverlapping small polaron tunneling (NSPT) models. Furthermore, the electrical properties were elucidated by impedance spectroscopy, which shows a non-Debye type relaxation process. The presence of two distinct dynamic mechanisms in the x = 0.05 sample, confirmed by scaling behavior, suggests a nuanced temperature-dependent shift in the primary electrical conduction mechanism.