Ceramics for fusion reactors: The role of the lithium orthosilicate as breeder

Lithium-based oxide ceramics are studied as breeder blanket materials for the controlled thermonuclear reactors (CTR). Lithium orthosilicate (Li4SiO4) is one of the most promising candidates because of its lithium concentration (0.54 g/cm3), its high melting temperature (1523 K) and its excellent tritium release behavior. It is reported that the diffusion of tritium is closely related to that of lithium, so it is possible to find an indirect measure of the trend of tritium studying the diffusivity of Li+.In the present work, the synthesis of the Li4SiO4 is carried out by Spray drying followed by pyrolysis. The study of the Li+ ion diffusion on the sintered bodies, is investigated by means of electrical conductivity measurements. The effect of the γ-ray irradiation is evaluated by the impedance spectroscopy method (EIS) from room temperature to 1173 K.The results indicate that the síntesis process employed can produce Li4SiO4 in the form of pebbles, finally the best ion species for the electrical conduction is the Li+ and is shown that the g-irradiation to a dose of 5MGy, facilitate its mobility through the creation of defects, without change in its conduction process.