Influence of V2O5 loading on the dielectric properties and AC conductivity of TiO2

Abstract

The interaction between TiO₂ and V₂O₅ can not only improve the physico-chemical properties of the material but also the dielectric and conductive properties of the material. For this purpose, TiO₂ samples with 5, 7, and 10 wt% V₂O₅ were prepared by the impregnation method to investigate the dielectric properties and AC conductivity. The phase composition and morphology of the V₂O₅/TiO₂ samples were characterized by X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM)-scanning transmission electron microscope (STEM). Regardless of the vanadium content, the samples exhibit non-spherical structures and particles with size in the range of 60–200 nm. The small V₂O₅ peaks in XRD were detected at 7.0 and 10 wt% V₂O₅. In addition, the specific surface area for 5 and 7 wt% V₂O₅ was determined to be 9.2 m²/g, but at 10 wt% V₂O₅ the surface area of the sample decreases to 7.5 m²/g as the titanium dioxide pores are filled by vanadium. The DR–UV–Vis spectra of V₂O₅/TiO₂ samples showed that the sample with 5 wt% V₂O₅ has isolated tetrahedrally coordinated V⁵⁺ species and increasing the V₂O₅ loading leads to the formation of octohedrally coordinated V⁵⁺ species in V₂O₅ clusters. Comparison of the Raman spectra of V₂O₅/TiO₂ and TiO₂ samples showed the formation of α-V₂O₅ on the TiO₂. In addition, a detailed analysis of the Nyquist diagrams shows how sensitively the electrical properties of the materials react to changes in temperature and frequency. Jonscher’s power law is used to analyze alternating current and conductivity, and it is found that the fluctuation of the exponent “s” adequately describes the conduction mechanism and agrees with CBH models. As the TiO₂ concentration increases, the value of the activation energy generated decreases. The higher presence of Ti⁴⁺ ions due to the increase in molar volume is the cause of this increase in charge carrier mobility. The effect of the grain and grain boundary on the overall impedance is revealed by a dielectric study, which also confirms that the combination of titanium dioxide and vanadium oxide nanoparticles improves the dielectric and AC conductivity of the samples.