Synthesis of Lithium Orthosilicate and Fabrication of Pebbles by the Solid-State Reaction Process

The fusion of deuterium and tritium is being considered for the energy source from fusion reactions, and on reaction each nuclei will produce one helium nuclei, one neutron and thermal energy. Deuterium is naturally available and the technologies to separate it from the compounds of hydrogen are well developed. Tritium can be produced by nuclear reaction of Li6 isotope with thermal neutrons, and natural lithium contains about 7.5% Li6. Lithium has a low melting point and readily reacts with oxygen, nitrogen and moisture present in air. So, lithium-containing ceramics, namely lithium orthosilicate and lithium titanate enriched in Li6 isotope, are being considered for tritium production by nuclear reaction with neutron. It was found that like lithium titanate, lithium orthosilicate can also be synthesised and pebbles can be fabricated by solid-state reaction process by using silica and lithium carbonate as raw materials. The advantage of this process is that the synthesis can be carried out at 800°C and fabricated pebbles can be sintered at 900°C to achieve the desired properties of the pebbles. Both these temperatures for synthesis and sintering are lower than that of the molten spray method. The experimental details and results are discussed in this paper.