Synthesis of zirconolite-based borosilicate glass–ceramics for nuclear waste immobilization

Abstract

The proper disposal of nuclear waste is crucial to reducing the risks brought by the development of nuclear energy. In this study, zirconolite-based borosilicate glass–ceramics immobilized with praseodymium oxide (Pr₆O₁₁) was studied and the influence of Pr₆O₁₁ content on their stability was also investigated. The synthesis of zirconolite at 1300°C exhibited excellent crystallinity and morphology when doping different amounts of Pr₆O₁₁. A mixture of barium borosilicate glass and different amounts of ceramic raw materials was sintered at 1300°C. X-ray diffraction results showed that as the ceramic content increased, zirconolite has more crystallinity. The energy dispersive spectroscopy mapping of the glass–ceramics revealed an even distribution of praseodymium across the surface. By conducting chemical durability testing, the leaching rate of praseodymium (NR_Pr) in glass–ceramics was 2.208 ± 0.012 × 10⁻⁶ g·m⁻²·day⁻¹ at day 28. The results of the chemical durability tests indicate that zirconolite-based borosilicate glass–ceramics exhibit good leaching performance. This strong leaching performance is essential for the solidification of radioactive nuclides, ultimately facilitating the safe disposal of nuclear waste.