Synthesis, Structural and Optical Properties of Li-Doped Molybdenum and Vanadium Oxide Nanocrystalline Films

Abstract

X-ray diffraction (XRD) and optical properties of (x)Li 2 O-(80-x)V 2 O 5-(20)MoO 3 (where 0 ≤ x ≤13 mol.%) films were studied. A sol-gel method (colloidal route) based on V 2 O 5 •nH 2 O hydro-gel was developed to synthesize these films. X-ray diffraction (XRD), was used to identify the structure of the obtained nanocrystals. Homogenous nanocrystals of 7.6 nm in size was obtained. Optical measurements were carried out using a double-beam spectrophotometer. The optical constants such as refractive index n, the extinction coefficient k, absorption coefficient α, and optical band gap have been evaluated. The optical spectra of some samples exhibited two distinct regions: one at high energy, which suggests a direct forbidden transition with optical gap increases with increase in Li-content. and other at low-energy band, suggests a direct allowed transition with optical gap ranging from 0.40 to 0.50 eV. Additional calculations applying the real part of the optical dielectric function led to the evaluation the ratio of the charge carrier concentration and their effective mass. The sol-gel method is fit for the preparation of (x) Li 2 O-(80-x)V 2 O 5-(20)MoO 3 material which may offer some favorable properties for commercial application.