Glasses with composition (60 x)V2O5–40TeO2 x MoO3 with 20 6 x 6 60 (in mol%) have
been prepared using the usual melt quenching method. The optical absorption spectra of
the glasses have been recorded in the wavelength range 300–800 nm. The position of
the absorption edge and therefore the optical band gap values were found to be depend
on the glass composition. For these glasses, the optical band gap was found to be in the
range 2.03–2.86 eV with increasing of MoO3 concentration. The absorption spectrum fit-
ting method was employed to obtain the energy gap. In this method, only the measure-
ment of the absorbance spectrum of the glass is needed. For each sample, the width of
the band tail was determined. Also, the density and glass transition temperature values
indicate that the rigidity and packing of the samples increase with increase in MoO3 con-
centration as a network former.