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

Abstract

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.