Copper Valence and Local Environment in Aluminophosphate Glass-Ceramics for Immobilization of High Level Waste from Uranium-Graphite Reactor Spent Nuclear Fuel Reprocessing. Issue 1744 (2015)

• Record Type: Journal Article
• Authors: Stefanovsky, Sergey V.; Shiryaev, Andrey A.; Remizov, Michael B.; Belanova, Elena A.; Kozlov, Pavel A.; Myasoedov, Boris F.
• Editors: Gin, S.; Jubin, R.; Matyáš, J.; Vance, E.
• Is Part Of: MRS proceedings. Issue 1744:(2015)
• Page Start: 79
• Page End: 84
• Publication Date: 2015
• Subjects: Cu, -- extended x-ray absorption fine structure(EXAFS), -- electron spin resonance; Electrical engineering -- Congresses; Physics -- Congresses; Materials -- Research -- Congresses; Materials science -- Congresses; 620.11
• DOI: 10.1557/opl.2015.312
• Languages: English
• ISSNs: 0272-9172

Abstract

ABSTRACT: Copper valence and environment in two sodium aluminophosphate glasses suggested for immobilization of HLW from reprocessing of spent fuel of uranium-graphite channel reactor (Russian AMB) were studied by XRD, SEM/EDX, XAFS and EPR. Target glass formulations contained ∼2.4-2.5 mol.% CuO. The quenched samples were predominantly amorphous. The annealed MgO free sample had higher degree of crystallinity than the annealed MgO-bearing sample but both them contained orthophosphate phases. Cu in the materials was partitioned in favor of the vitreous phase. In all the samples copper is present as major Cu 2+ and minor Cu + ions. Cu 2+ ions form planar square complexes (CN=4) with a Cu 2+ -O distance of 1.93-1.95 Å. Two more ions are positioned at a distance of 2.76-2.86 Å from Cu 2+ ions. So the Cu 2+ environment looks like a strongly elongated octahedron as it also follows from the absence of the pre-edge peak due to 1s→3d transition in Cu K edge XANES spectra of the materials. Cu + ions form two collinear bonds at Cu + -O distances of 1.80-1.85 Å. Thus average Cu coordination number (CN) in the first shell was found to be 2.7-3.0.