Immobilization of gadolinium in borate-tellurate glasses

Abstract

Glasses in the xGd2O3·(100-x)[6TeO 2·4B2O3] system, where x = 0, 5, 10, 15, 25 and 30 mol%, have been prepared from melt quenching method. The structural changes were studied by FTIR spectroscopy and DFT calculations. The FTIR spectroscopy data for these systems show that the gadolinium ions have a strong affinity towards the structural units containing non-bridging oxygens, which are negative-charged, because they are readily available for charge compensation. So that, it seems that the content of [BO4] structural units cannot become higher, because the modified [BO3] units containing one or more B-O-Gd bonds are unable to accept a fourth oxygen atom. On the other hand, the gadolinium ions have also an affinity pronounced towards [TeO3] structural units yielding the deformation of the Te-O-Te linkages. The compositional evolution of the network was accommodated with excess of oxygen by the formation of orthoborate structural units, disintegration of some boroxol rings and radical rearrangement of the network formed by the [TeO6] octahedral units. © 2009 IOP Publishing Ltd.