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 2B2g→2A1g, 2B2g→2B1g and 2B2g→2Eg, 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 51V 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 C4v 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.