Investigating the synthesis, reaction pathways, melting points and air sensitivity of Octalithium ceramics, Li8MO6, with M = Sn, Zr, Pb, and Ce

• A pure phase synthesis route was given for Li 8 SnO 6, Li 8 ZrO 6, Li 8 PbO 6 and Li 8 CeO 6 • Li 8 PbO 6 was reduced when heated in Ar at 800°C for extended periods • Melting points: Li 8 SnO 6 1238°C, Li 8 CeO 6 1112°C, Li 8 PbO 6 1011°C, Li 8 ZrO 6 1266°C • All compounds formed Li 2 CO 3 after one month exposure to air • The lattice thermal expansion was measured from 25 – 900°C 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 Li 2 TiO 3 [ 2 ], and the measured melting points were Li 8 SnO 6 1238 ± 7°C, Li 8 CeO 6 1112 ± 6°C, Li 8 PbO 6 1011 ± 3°C and Li 8 ZrO 6 1266 ± 5°C. The compounds all formed Li 2 CO 3 after long air exposures and Li 8 SnO 6 , Li 8 PbO 6 and Li 8 ZrO 6 also produced lower lithium stoichiometry phases as impurities (Li 2 SnO 3 , Li 4 PbO 4 , Li 2 PbO 3 and Li 6 Zr 2 O 7 ). Li 8 CeO 6 displayed no crystalline impurities after 20 hours but after one month had decomposed wholly to Li 2 CO 3 , CeO 2 , Li 2 O and LiOH.