Phase composition control of biphasic tritium breeding ceramics and correlation behavior of lithium and tritium

Abstract Biphasic tritium breeding ceramics were prepared by the microwave-induced solution combustion (MSCS) method in a single step. The phase ratio of lithium titanate and lithium silicate can be effectively controlled by changing the Si/Ti atom ratios in the aqueous precursor. The combustion process is completed within ∽100 s, and the nano-structure Li2TiO3-Li4SiO4 ceramic power can be obtained directly after the combustion reaction. This preparation approach is promising for the scale production of tritium breeding ceramics with various chemical compositions. Besides, as Li4SiO4 absorbs CO2, which leads to the formation of Li2SiO3 and Li2CO3, the powder needs further calcination treatment at 983 – 1023 K. For the ceramic bodies sintered at 1073 K and 1223 K, the Li2TiO3-xLi4SiO4 (x = 1) ceramic shows high phase stability and small grain size of ∽200 nm. However, for the case of Li2TiO3-xLi4SiO4 (x = 0.5) ceramic, the Li4SiO4 phase is transformed into Li2TiSiO5 and Li2SiO3 with a lithium loss in sintering process. On the other hand, the evaluation of the tritium migration behavior using the electrochemical workstation is performed. The calculation results show that the lithium diffusion coefficient (DLi) can reflect the Dtritium for the ceramics with various phase compositions. It is found that the Dtritium is not proportional to the lithium density in the ceramic. The Li2TiO3-xLi4SiO4 (x = 1) ceramic has a favorable tritium migration behavior than mono-Li4SiO4 ceramic.