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

Abstract

• High purity of the Li2TiO3-xLi4SiO4 ( x = 0.5, 1) biphasic ceramic powders . • A dependence on the phase ratio for the high-temperature stability. • Favourable tritium diffusion coefficient for the biphasic Li2TiO3-xLi4SiO4. • Fast prediction of the tritium release property by the electrical characteristics. 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 Li 2 TiO 3 -Li 4 SiO 4 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 Li 4 SiO 4 absorbs CO 2, which leads to the formation of Li 2 SiO 3 and Li 2 CO 3 , the powder needs further calcination treatment at 983 – 1023 K. For the ceramic bodies sintered at 1073 K and 1223 K, the Li 2 TiO 3 - x Li 4 SiO 4 ( x = 1) ceramic shows high phase stability and small grain size of ∽200 nm. However, for the case of Li 2 TiO 3 - x Li 4 SiO 4 ( x = 0.5) ceramic, the Li 4 SiO 4 phase is transformed into Li 2 TiSiO 5 and Li 2 SiO 3 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 ( D Li ) can reflect the D tritium for the ceramics with various phase compositions. It is found that the D tritium is not proportional to the lithium density in the ceramic. The Li 2 TiO 3 - x Li 4 SiO 4 ( x = 1) ceramic has a favorable tritium migration behavior than mono-Li 4 SiO 4 ceramic.