Spectroscopic, thermal, structural and electrical studies on VO2+ ions doped PVA/MAA: EA polymer blend films

Pure and VO2+ ions doped PVA/MAA:EA polymer blend films were prepared by a solution casting method. XRD pattern reveals an increase in amorphicity with increase in doping. The dTGA study shows an enhancement of thermal stability of the system with increase in dopant concentration. The optical absorption spectrum exhibits three bands corresponding to the transitions B-2(2g) -> (2)A(1g) -> B-2(2g) -> B-2(1g) and B-2(2g) -> E-2(g), characteristic of VO2+ ions in octahedral symmetry with tetragonal distortion and reflects that the optical band gap decreases with the increase of mol% of VO2+. EPR spectra of all the doped samples show a characteristic eightline hyperfine structure of VO2+ ions, which arises due to the interaction of unpaired electron with the V-51 nucleus. The spin-Hamiltonian parameters (g and A) evaluated from the EPR spectra confirm that the vanadyl ions exist as VO2+ ions in octahedral co-ordination with a tetragonal compression and have a C-4v symmetry. The impedance spectroscopic study shows that the addition of VO2+ ions into the polymer blend system enhances the ionic conductivity which is explained in terms of an increase in the amorphicity. (C) 2019 The Authors. Publishing services by Elsevier B.V. on behalf of Vietnam National University, Hanoi.