High lithium content silicates: A comparative study between four routes of synthesis

Lithium-silicate ceramic is a material widely used in the energy field, here studied for its application as solid breeder blanket in the future fusion reactors. Considering the difficulty in reaching a unique stable phase together with a spherical shape, the advantages and disadvantages of solid-state reaction, drying gels in rotary evaporator, spray drying and reflux in alcoholic media methods are here considered for the production of lithium orthosilicate (Li4SiO4). The fabrication of a material with high Li-content such as the lithium oxosilicate (Li8SiO6) is also investigated. Phase compound identification, mass and heat evolution are followed by X-Ray Diffraction, thermo-gravimetrical analysis (DTA/TG) and infrared spectroscopy (ATR/IR) while the samples morphology is observed by the Scanning Electron Microscope. The spray drying method results to be the best fabrication way to achieve the desired compromise between shape and crystallinity in the case of the orthosilicate ceramic. The oxosilicate phase is reached by solid-state route and in small amount, by spray drier and reflux processes.