Fabrication of Li4SiO4@Li2TiO3 core-shell tritium breeding materials with controlled thickness and improved moisture stability via a shrinkage matching process

In this study, a shrinkage matching process was developed to achieve synchronous shrinkage of Li₄SiO₄ and Li₂TiO₃ during sintering, enabling the successful fabrication of a core-shell structured tritium breeder material with a Li₄SiO₄ core and Li₂TiO₃ shell to address the hygroscopicity of Li₄SiO₄. The shell thickness of the Li₄SiO₄@Li₂TiO₃ core-shell breeding materials can be controlled in the range of 0–235 μm, and their moisture stability was systematically investigated at 10 % RH, 50 % RH, and 80 % RH. Results showed that increasing shell thickness significantly enhanced phase and mechanical stability in humid environments, although excessively thick shells reduced overall Li content. To understand these improvements, the moisture stabilization mechanism of this core-shell breeding ceramics was comprehensively analyzed. Notably, the core-shell pebbles with a shell thickness of 146 μm exhibited a satisfactory crushing load (80.5 N) and a suitable Li content (16.87 wt%), and maintained superior moisture stability after storage at 80 % RH for 14 days. This novel concept, preparation route, and elucidated mechanism of utilizing Li₂TiO₃ shell to enhance the moisture stability of Li₄SiO₄ matrix provide a new strategy for performance enhancement of advanced tritium breeding materials.