Dynamic counteraction of Maxwell–Wagner polarization with frequency-dispersive pseudo-inductive effect in V₂O₅ nanorods: role of oxygen vacancy and detrapped carriers towards RF decoupler

Abstract A frequency-dispersive impedance analysis of polycrystalline V 2 O 5 nanorods is performed under an external DC field to investigate the intricate interplay between dielectric polarization and delocalized carrier transport. Rietveld refinement of powder x-ray diffraction patterns confirms the phase purity and provides essential crystallographic information, while SEM and HRTEM analyses offer comprehensive insights into the morphology. The elemental composition, chemical bonding, stoichiometry, and surface characteristics are examined using XPS spectra. Evidence of oxygen vacancies from both Rietveld refinement and XPS analysis motivates a DFT-based comparative study of the electronic properties of pristine V 2 O 5 and oxygen-vacancy-incorporated V 2 O 5 supercell. Beyond the conventional frequency-dispersive dielectric, impedance, and admittance spectra, a key observation is the capacitance switching from positive to negative values at higher frequencies (∼MHz range) under varying external DC bias. Detailed fitting of the experimental data reveals a bi-relaxation mechanism: one component arises from Maxwell–Wagner interfacial polarization between grain cores and boundaries, dominant at lower frequencies, while the second mechanism involves the hopping of delocalized carriers, resulting in a high-frequency degenerative pseudo-inductive response. Notably, both of the characteristic frequencies decrease with increasing bias. The counteractive interference between these mechanisms manifests in the asymmetric Breit–Wigner–Fano profile observed in the dielectric susceptance spectra. Finally, the equivalent circuit parameters and overall frequency-dispersive characteristics suggest the potential application of V 2 O 5 -based metal–insulator–metal devices as radio-frequency decouplers.