Li6BaLa2Ta2O12 Solid-State Probe for Studying Li Activity in Molten Sn-Li Alloys

Metals or alloys that are liquid at or near room temperature are of interest of the scientific community due to the versatility of their applications. Considering the nuclear fusion energy applications, Sn-Li alloys appear as a great candidate for plasma facing materials. However, plasma interactions can induce alterations on the lithium concentration and, as a consequence, modify the properties of the LM. Therefore, in order to prevent these situations, thermodynamic data such as activity coefficients and analytical devices capable of monitoring the lithium content in these alloys are of great interest. In this work, a lithium sensor based on the Li6BaLa2Ta2O12 solid-state electrolyte was used to determine lithium activity correlations for Sn-Li alloys at 400 and 500 °C. It was observed that the activity coefficient was constant for lithium concentrations lower than 8.5 at% with values, at the infinite dilution condition, of 8.4·10‒5 at 400 °C and 2.7·10‒4 at 500 °C, respectively. Above this concentration (from 8.5 to 16.5 at%Li), the activity coefficient varied with lithium concentration. In this case, correlations between lithium activity and the lithium atomic fraction were obtained.