Raman spectroscopic study of Nd-doped 10Na 2O–90TeO 2 glasses

Abstract

Over the Nd 2O 3 concentration region from 0.1 to 2.5 mol%, our Raman spectroscopic study showed that adding Nd to a base 10Na 2O–90TeO 2 tellurite glass converts TeO 4 trigonal bipyramid (tbp) units to TeO 3 trigonal pyramid (tp) units and possibly some terminal TeO 3+1 polyhedra. The Nd effect on the speciation of tellurite structural groups is similar to that of other monovalent (such as alkalis), divalent (such as Zn), and trivalent (such as La) metal cations. The previously observed Nd–O local structural transition was also found in the current study. Namely, a transition near 1 mol% Nd 2O 3 was observed in the correlations, both band position and intensity, between two Raman stretching vibration bands near 600 and 730 cm −1 . The former represents the stretching vibration mode of TeO 4 tbp units and the latter represents the stretching vibration mode of TeO 3 tp units. A Raman band, near 465 cm −1 , represents a bending vibration mode of Te–O–Te (or O–Te–O) linkages. Our study showed a significant decrease in the E-band intensity of the glass with 2.5 mol% Nd 2O 3. It follows that a considerable structure disruption of the tellurite network takes place when the Nd cation is close to its solubility limit.