Investigating the Synthesis, Reaction Pathways, Melting Points and Air Sensitivity of Octalithium Ceramics, Li8MO6, with M = Sn, Zr, Pb, and Ce

Octalithium ceramics (Li8MO6, M = Zr, Pb, Ce, Sn) are highly lithium dense compounds that have been modelled to offer significantly higher tritium breeding ratios (TBRs) compared to the current candidate breeder materials [1]. This investigation demonstrates and investigates a solid-state synthesis route and the importance of atmosphere for the formation phase pure ceramics of all four compounds. All tested octalithium compounds showed higher coefficients of lattice thermal expansion (CTEs) from 25 - 900°C compared to Li2TiO3 [2], and the measured melting points were Li8SnO6 1238 ±7°C, Li8CeO6 1112 ±6°C, Li8PbO6 1011 ±3°C and Li8ZrO6 1266 ±5°C. The compounds all formed Li2CO3 after long air exposures and Li8SnO6, Li8PbO6 and Li8ZrO6 also produced lower lithium stoichiometry phases as impurities (Li2SnO3, Li4PbO4, Li2PbO3 and Li6Zr2O7). Li8CeO6 displayed no crystalline impurities after 20 hours but after one month had decomposed wholly to Li2CO3, CeO2, Li2O and LiOH.