Effect of Bi incorporation in adjusting structural, optical, and electrical conduction mechanism of xBi2O3-(0.40-x) 2 O 3-(0.40-x) Fe2O3-0.35V2O5-0.25P2O5 2 O 3-0.35V 2 O 5-0.25P 2 O 5 glass nanocomposites

This study investigates the influence of Bismuth incorporating on the structural, optical, as well as electrical properties of bulk glassy samples composed of xBi2O3-(0.40-x) 2 O 3-(0.40-x) Fe2O3-0.35V2O5-0.25P2O5 2 O 3-0.35V 2 O 5-0.25P 2 O 5 (x x = 0, 0.1, 0.2, 0.3, and 0.4). The FESEM and XRD data reveal the presence of nano-crystallites and changes in amorphousness. The density of the glassy composites increases from (3.63-4.92) g.cm-3-3 due to structural modifications, which is also confirmed by the X-ray diffraction pattern. Optically, these glasses show alterations in absorption coefficient (alpha) and extinction coefficient (k), k ), making them suitable for Near-Infrared (NIR) applications. Tauc's spectral analyses demonstrate a reduced optical bandgap energy ( E opt ) from (2.42-2.00) eV and increased refractive index (n) n ) from (2.56-2.70) with higher Bi2O3 2 O 3 content, highlighting its role in modulating optical properties. The measured Urbach energy values increase from (0.25- 0.56) eV indicating structural modifications. Spectroscopic properties such as polarizability, metallization constant are examined, confirming a shift towards semi-conductive behaviour. Electrical conductivity is studied using Jonscher's universal power law along with the Almond- West formalism, showing that DC conductivity increases with higher Bi2O3 2 O 3 content due to a decrease in hopping distance from 11.23 to 5.21 and an increase in the values of defect pair states. The Mott and Greaves model recommends that DC conductivity is influenced by the small polaron hopping model, while the Pan and Ghosh model explains AC scaling based on conductivity relaxation processes related to small polarons.