Lead metallic-lead dioxide glasses as alternative of immobilization of the radioactive wastes

摘要

In this work, we report structural, optical and electrochemical investigations on the gadolinium-lead glass system with the xGd(2)O(3)center dot(100 - x)[4PbO(2)center dot Pb] composition where x = 0, 1, 5, 10, 15 mol% Gd2O3 obtained by the melt quenching method. The studied homogeneous glass system was characterized by X-ray diffraction (XRD), infrared (IR) spectroscopy, ultraviolet-visible (UV-VIS) spectroscopy, electron paramagnetic resonance (EPR) spectroscopy, and cyclic voltammety (CV) measurements. The purpose of this paper was i) to immobilize the gadolinium ions in the lead-lead dioxide glasses and ii) to investigate the structural, optical and electrochemical properties of the obtained glasses for possible applications in the radioactive waste recycling. IR data show that the [PbO6] octahedral structural units do not accommodate with the excess of non-bridging oxygen, [PbO3] pyramidal units are suitable neighbors for the gadolinium ions and [GdOn] entities will be intercalated in the host matrix. The EPR spectra of Gd+3 ions in lead-lead dioxide glasses exhibit four resonance lines situated at about g approximate to 2.0; 2.8; 4.8 and 6. The EPR signals located at about g similar to 2; 2.8 and 6 are known as the U-spectrum of Gd+3 ions situated in higher symmetry which can be readily accommodated in a vitreous system whereas the sharpness of the signal situated at about g similar to 4.8 is associated with Gd+3 ions having low coordination numbers. These structural modifications are supported by the increase in the intensity of the UV-VIS absorption bands associated to the electronic transitions of the Pb+2 and Gd+3 ions and the formation of non-bridging oxygen centers. Electrochemical performances of electrode glasses show the pronounced mobility of the lead ions comparative with the gadolinium ions. (C) 2014 Elsevier B.V. All rights reserved.