Study of optical properties of highly oriented nanocrystalline V 2O 5•nH 2O films doped with K ions

Abstract

Optical transmission and reflection measurements of highly oriented nanocrystalline K xV 2O 5•nH 2O films (0 ≤ x < 0.01) were studied. The optical constants such as, refractive index, the extinction coefficient, absorption coefficient, optical band gap have been calculated. The optical spectra of all samples exhibited two distinct regions of optical gap, E op1 suggesting a direct allowed transition with optical gap ranging from 0.37 up to 0.42 eV and E op2 suggesting a direct forbidden transition with optical gap ranging from 2.02 up to 2.23 eV. This indicates that K xV 2O 5• nH 2O films have more than one type of conduction mechanism. © 2012 The Author(s).