Crystallization study of (TiO2, ZrO2)-rich SiO2-Al2O3-CaO glasses Part I Preparation and characterization of zirconolite-based glass-ceramics

• Published in: Journal of materials science Vol. 38; no. 4; pp. 843 - 852
• Main Authors: Loiseau, P, Caurant, D, Majerus, O, Baffier, N, Fillet, C
• Format: Journal Article
• Language: English
• Published: Heidelberg Kluwer Academic Publishers 15.02.2003; Springer; Springer Nature B.V
• Subjects: Actinides; Aluminum oxide; calcium oxide; Composition; Cross-disciplinary physics: materials science; rheology; Crystal structure; Crystallinity; Crystallization; crystals; Devitrification; Electron paramagnetic resonance; electron paramagnetic resonance spectroscopy; Electron spin; Exact sciences and technology; fuels; glass; Glass ceramics; Growth from solid phases (including multiphase diffusion and recrystallization); ions; Materials science; Methods of crystal growth; physics of crystal growth; Neodymium; Nuclear fuels; nuclear power; Nuclear power reactors; Nuclear reactors; Nucleation; Physics; Power reactors; radioactive waste; Radioactive wastes; Radioisotopes; radionuclides; Reprocessing; Silicon dioxide; Spent nuclear fuels; Spin resonance; Titanium dioxide; Zirconium dioxide; Scanning electron microscopy; Additives; Ternary systems; Crystallization; XRD; Experimental study; Titanium Oxides; Characterization; Aluminium Oxides; Zirconolite; Silicon Oxides; Radioactive waste storage; Calcium Oxides; Aluminosilicate glass; Zirconium Oxides; Glass ceramics; Calcium Aluminosilicates
• ISSN: 0022-2461; 1573-4803
• DOI: 10.1023/A:1021873301498

Nuclear power reactors generate long-lived radionuclides such as minor actinides (Np, Am, Cm) which are mainly responsible for the long term radiotoxicity of high level nuclear wastes obtained after reprocessing of nuclear spent fuel. Specific highly durable matrices such as glass-ceramics appear as good candidates for the immobilization of minor actinides. This work concerns the synthesis and the characterization of zirconolite (CaZrTi₂O₇) based glass-ceramics prepared by controlled devitrification of (TiO₂, ZrO₂)-rich SiO₂-Al₂O₃-CaO parent glasses for which neodymium was selected to simulate the radioactive trivalent minor actinides. The present study reports the effect of increasing TiO₂, ZrO₂ and CaO amounts in glass composition on the structure and the composition of the zirconolite crystals (formed as the only crystalline phase in the bulk of the glass), on their nucleation rate I(Z) and on the volume proportion of crystalline phase V of the glass-ceramics. It appears that I(Z) and V strongly increase when the parent glass composition changes. Neodymium electron spin resonance (ESR) shows that the total amount of Nd³⁺ ions incorporated in the zirconolite phase increases with TiO₂, ZrO₂ and CaO amounts in parent glass composition.