Correlating structural and electronic properties with energy dissipation, polarization dynamics, and dielectric responses in V2O5-NiO-Sb2O3 micro-ceramics

Abstract

Complex oxides V_2-xNi_2xSb_xO_5-δ (0.05≤x ≤ 0.08) were synthesized via solid-state reaction. XRD confirmed the dominant orthorhombic V₂O₅ phase with minor NiV₂O₆ and SbVO₄ phases. XPS analysis revealed V⁵⁺, Sb³⁺, and Ni²⁺ oxidation states. A blue shift in the reflectance edge with increasing Sb and Ni concentration indicates a decrease in the band gap from 2.28 eV to 2.22 eV. The electrical properties probed across a broad frequency range (10 Hz-10 MHz), revealed a strong dependence on Sb and Ni molar concentrations. At 10 Hz, the dielectric constant initially decreases from 32,359 to 6335 with increasing mole fraction (x = 0.05 to x = 0.06), then increases from 18,316 for x = 0.07 to 25,577 for x = 0.08. The tangent loss factor mirrored the trend observed in the dielectric constant, highlighting the dependence of energy dissipation and polarization dynamics on the mole fraction of Sb and Ni. Impedance analysis revealed a frequency-dependent ionic-to-electronic conductivity transition, well-described by the Almond-West formalism.