Rietveld refinement, core level electron shell structure and frequency-dependent dielectric behavior of vanadium bismuth oxide microstructures

Abstract

Solid-state reaction method was employed to synthesize a series of complex compound system V2-xBi2xO5-δ (0.01 ≤ x ≤ 0.04), and their electrical properties at room temperature were examined through impedance spectroscopy within the frequency range of 40 Hz to 10 MHz. The X-ray diffraction (XRD) is refined to obtain the complete crystallographic profile of the compounds. The frequency-dependent conductivity exhibited adherence to Jonscher's universal power law across all compositions. As the bismuth concentration increased from x = 0.01 to 0.04, both AC and DC conductivity showed a systematic increase. AC conductivity raised from 3.17 × 10−4Sm−1 to 4.3 × 10−4 Sm−1 at 10 MHz, while DC conductivity increased between 1.56 × 10−4Sm−1 and 2.28 × 10−4Sm−1. The dielectric constant (εr') decreased with increasing frequency, stabilizing around 100 kHz. The electric modulus peaks at higher frequencies, reflecting relaxation processes, and approaches zero at lower frequencies due to the absence of electric polarization.