Cs₃Bi₂I₉, a defect perovskite derivative, is a potential host phase to immobilize iodine and cesium with high waste loadings. In this work, two strategies were explored to form Cs₃Bi₂I₉-silica composites and a core-shell structure in order to improve chemical durability of waste form materials meanwhile maintaining high waste loadings. Cs₃Bi₂I₉ loadings as high as 70 wt.% were incorporated into a silica matrix to form silica-ceramic composites, and 20 wt.% Cs₃Bi₂I₉ was encapsulated into silica to form a core–shell structure by low temperature spark plasma sintering. Chemical durability of the composite and core-shell waste forms was evaluated by semi-dynamic leaching experiments, and Cs and I were incongruently released from waste form matrices. A BiOI alteration layer formed, acting as a passivation layer to reduce the release of radionuclides. The long-term iodine release rate was low (30 mg m⁻² day^-1) for the 70 wt.% Cs₃Bi₂I₉–silica composite leached in deionized water at 90 °C, which can be further reduced to 5 × 10⁻³ mg m⁻² day⁻¹ for the 20 wt.% core-shell structure. This work highlights a robust way to immobilize the highly mobile radionuclides with high waste loadings through encapsulation into durable matrices and a surface passivating mechanism that can greatly reduce the elemental transport from waste form materials and significantly enhance their chemical durability.

Cs ₃ Bi ₂ I ₉（钙钛矿的一种缺陷衍生物）是潜在的宿主相，可以固定高废物量的碘和铯。在这项工作中，探索了两种策略来形成Cs ₃ Bi ₂ I _9-二氧化硅复合材料和核-壳结构，以提高废物形式材料的化学耐久性，同时保持较高的废物载量。将负载量高达70 wt。％的Cs ₃ Bi ₂ I ₉掺入二氧化硅基质中以形成二氧化硅-陶瓷复合材料，以及20 wt％的Cs ₃ Bi ₂ I ₉通过低温火花等离子体烧结将其包裹在二氧化硅中以形成核-壳结构。通过半动态浸出实验评估了复合废料和核壳废料的化学耐久性，Cs和I从废料基质中释放出来。形成BiOI蚀变层，用作钝化层以减少放射性核素的释放。在70 °C的去离子水中浸出的70 wt。％Cs ₃ Bi ₂ I _9-二氧化硅复合材料的长期碘释放率很低（30 mg m ^-2天^-1）。×10 ^-3 mg m ^-2天^-1对于20重量％的核-壳结构。这项工作突出了通过将其封装到耐用基质中和表面钝化机制来固定具有高废物负载的高移动性放射性核素的强大方法，该方法可以大大减少废物形式材料的元素迁移并显着提高其化学耐久性。