Crystallization study of (TiO sub 2 , ZrO sub 2 )-rich SiO sub 2 -Al sub 2 O sub 3 -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: 15-02-2003
• ISSN: 0022-2461

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 (CaZrTi sub 2 O sub 7 ) based glass-ceramics prepared by controlled devitrification of (TiO sub 2 , ZrO sub 2 )-rich SiO sub 2 -Al sub 2 O sub 3 -CaO parent glasses for which neodymium was selected to simulate the radioactive trivalent minor actinides. The present study reports the effect of increasing TiO sub 2 , ZrO sub 2 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 Nd exp 3+ ions incorporated in the zirconolite phase increases with TiO sub 2 , ZrO sub 2 and CaO amounts in parent glass composition.