Elastic and structural studies of Er3+ doped TeO2-Nb2O5-ZnO tellurite glasses / Mohd Firdaus Sharin

Erbium doped tellurite glass with starting composition of 75TeO2-(10-x)Nb2O5-10ZnO- (x)Er2O3 (x = 0-2.5 mol%) have been prepared by melt-quenching method and the effect of Er3+ doped on elastic and structural properties was studied. Ultrasonic longitudinal and shear velocity showed initial decrease of 1.39% and 3.29% respectively at x = 0.5 mol%. For x > 0.5 mol%, longitudinal velocity showed an increase and fully recovery at x = 2.5 mol%. Longitudinal, shear and Young's modulus showed similar drop at x = 0.5 mol% followed by recovery at x > 0.5 mol% while bulk modulus showed an increased with Er2O3. Infrared (IR) a. Infrared (IR) absorption spectra showed increase in intensity of NbO6 assigned peak accompanied by increase in intensity of ZnO4 tetrahedral and TeO4 trigonal bipyramid (tbp) assigned peaks indicating formation of both non-bridging oxygen (NBO) and bridging oxygen (BO) respectively, at JC = 0.5 mol% of Er2O3. The initial drop in ultrasonic velocity and related elastic moduli observed at x = 0.5 mol% indicates weakening of network rigidity of the glass system due to structural modification as an effect of Er3+ doped in small amount and existence of NBO. However, further increase of Er3+ doped at x > 0.5 mol% contributed to increase in BO causing rigidity of the glass network to improve.