STRUCTURAL-PROPERTIES OF V2O5-LI2O-B2O3 GLASSES DOPED WITH COPPER-OXIDE

The optical transmission spectra in a wide range of wavenumbers: infra red (IR), visible and ultra-violet (UV) regions have been measured for lithium berate glasses of compositions xCuO:(3 - x)V2O5:37Li(2)O:60B( 2)O(3) mol% (where x = 0.0-0.5). From the IR analysis, it was found th at the different berate structural groups in these glasses are not aff ected by substitution of V2O5 by small quantities of CuO. The UV visib le results are analyzed with the aim of determining the optical energy gap, E(opt), and the width of the localized states in the band gap. T he values for E(opt) are found to decrease as CuO content increases. S ubstitution of V2O5 by CuO creates additional localized states, due to Cu+2, overlapping with that due to the matrix and extended to the mob ility gap.