Reaction Kinetics for the Synthesis of Li4SiO4 by Solid State Reaction from Li2SiO3 and Li2CO3 for Tritium Breeder

Currently, Li₄SiO₄ has been considered one of the best candidates for tritium breeders. Besides, it has also been suggested to be the promising high-temperature carbon dioxide (CO₂) solid sorbent and lithium ion conducting material. As the knowledge of reaction kinetics can offer either a practical or theoretical purpose for predicting and optimizing the reaction process, the kinetics of formation of Li₄SiO₄ from Li₂CO₃ and Li₂SiO₃ were investigated by non-isothermal thermogravimetric technique at four different heating rates. The Malek method results showed that the reaction was the Avarami–Erofeev model, i.e., at about 650 °C the Li₂SiO₃ and Li₂CO₃ with molar ratio of 1:1 formed Li₄SiO₄ crystal nucleus randomly, and then it grew by the diffusion of Li and O through Li₄SiO₄ layer. And the diffusion stage was the rate controlling step. The performances of Li₄SiO₄ pebbles fabricated by a graphite bed process using Li₂SiO₃ and Li₂CO₃ were also evaluated.