Effect of compositional variations on charge compensation of AlO{sub 4} and BO{sub 4} entities and on crystallization tendency of a rare-earth-rich aluminoborosilicate glass

• Published in: Materials research bulletin Vol. 44; no. 9
• Main Authors: Quintas, A., Caurant, D., Majerus, O., Charpentier, T., Dussossoy, J.-L.
• Format: Journal Article
• Language: English
• Published: United States 15-09-2009
• Subjects: BARIUM IONS; CALCIUM IONS; CATIONS; CESIUM IONS; CRYSTALLIZATION; ELECTRON MICROSCOPY; LITHIUM IONS; MAGNESIUM IONS; MATERIALS SCIENCE; NUCLEAR MAGNETIC RESONANCE; POTASSIUM IONS; RARE EARTHS; RUBIDIUM IONS; SILICON OXIDES; SODIUM IONS; STRONTIUM IONS; X-RAY DIFFRACTION
• ISSN: 0025-5408; 1873-4227
• DOI: 10.1016/J.MATERRESBULL.2009.05.009

This paper presents the structural and crystallization study of a rare-earth-rich aluminoborosilicate glass that is a simplified version of a new nuclear glass proven to be a potential candidate for the immobilization of highly concentrated radioactive wastes that will be produced in the future. In this work, we studied the impact of changing the nature of alkali (Li{sup +}, Na{sup +}, K{sup +}, Rb{sup +}, Cs{sup +}) or alkaline-earth (Mg{sup 2+}, Ca{sup 2+}, Sr{sup 2+}, Ba{sup 2+}) cations present in glass composition on glass structure (by {sup 27}Al and {sup 11}B nuclear magnetic resonance spectroscopy) and on its crystallization tendency during melt cooling at 1 K/min (average cooling rate during industrial process). From these composition changes, it was established that alkali cations were preferentially involved in charge compensation of (AlO{sub 4}){sup -} and (BO{sub 4}){sup -} entities in the glassy network comparatively to alkaline-earth cations. Whatever the nature of alkali cations, glass compositions containing calcium gave way to the crystallization of an apatite silicate phase bearing calcium and rare-earth (RE) cations (Ca{sub 2}RE{sub 8}(SiO{sub 4}){sub 6}O{sub 2}, RE = Nd or La) but melt crystallization tendency during cooling strongly varied with the nature of alkaline-earth cations.