Effect of glass composition on the crystallization of CePO4–borosilicate glass composite materials

Abstract

Glass–ceramic composite materials are composed of ceramic crystallites within a glass matrix. These materials have been suggested as nuclear waste forms; however, the formation of targeted crystal phases remains a challenge to utilizing these materials as waste forms. The crystallization of composite materials consisting of CePO4 dispersed in borosilicate glass at low temperatures was investigated in this study. The basicity of the borosilicate glass matrix was decreased to favour Ce3+ and the formation of CePO4 at low annealing temperatures using a one-step coprecipitation method. The basicity of the glass was lowered by removing the network modifier oxides from the glass composition. The crystalline phases, Ce oxidation states, and elemental distribution in CePO4–borosilicate glass composite materials were studied by powder X-ray diffraction, Ce L1- and L3-edge X-ray absorption near-edge spectroscopy, and scanning electron microscopy/energy dispersive X-ray spectroscopy. Lowering the glass basicity was successful in favouring the formation of CePO4 and had the added benefit of reducing the crystallization of unwanted crystal phases.