Structural, optical, thermal and conducting properties of V2−xLixO5−δ (0.15 ≤ x ≤ 0.30) systems

Abstract

Lithium-doped vanadates (V2−xLixO5−δ (0.15 ≤ x ≤ 0.30)) are synthesized by melt-quench method. The physical, structural, optical, thermal and conducting properties of as-quenched samples are investigated using various experimental techniques to study their suitability for electrolyte in battery/solid oxide fuel cell application. X-ray diffraction (XRD) patterns confirm the formation of three different crystalline phases. FTIR and Raman spectra indicate that the doping of Li2O into V2O5 leads to a transition from VO5 into VO4 structural unit. The optical diffused reflectance spectra revealed that the optical band gap (Eg) decreases from 2.2 to 2.08 eV while Urbach energy (EU) increases (0.31–0.41 eV) with the addition of Li2O content in place of vanadium. The thermal stability is studied by thermogravimetric analyser (TGA). The DC conductivity of the present samples is increased from 0.08 to 0.12 Scm−1 at 450 °C with Li2O doping. These materials can be used as electrolyte for battery/solid oxide fuel cell due to their good conductivity (~0.12 Scm−1) at 450 °C.