A comprehensive study on Li 4 Si 1−x Ti x O 4 ceramics for advanced tritium breeders

Hetero-element doped lithium orthosilicates have been considered as advanced tritium breeders due to the superior performances. In this work, Li4Si1−xTixO4 ceramics were prepared by proprietary hydrothermal process and multistage reactive sintering. The reaction mechanism of Li4Si1−xTixO4 was put forward. XRD and SEM analyses indicate that insertion of Ti leads to lattice expansion, which promotes the grain growth and changes the fracture mode. The compressive tests show that the crush load increases almost four times by increasing x from 0 to 0.2. However, the thermal conductivity and ionic conductivity are the best when x = 0.05 and x = 0.1, respectively. Thermal cycling stability of Li4Si1−xTixO4 pebbles was further appraised through investigating the changes of microstructure and crush load. After undergoing thermal cycling, the Li4Si1−xTixO4 still show higher crush load compared with Li4SiO4, despite Ti segregation in some samples. The x = 0.05 sample exhibits excellent thermal cycling stability. In summary, proper amount of Ti doping can improve the crush load, thermal and ionic conductivity, and thermal cycling stability of Li4SiO4.