Li6La3Ta1.5Y0.5O12 solid-state lithium sensor for molten alloys

Abstract

Different breeding blankets are proposed for tritium generation in nuclear fusion reactors. Some of the proposed strategies are based on the molten eutectic alloy Lithium - Lead. Since lithium will be consumed, this alloy's physical and chemical properties will vary as its composition changes. For this reason, analytical tools able to perform real-time and in-situ lithium monitoring are of great interest. Electrochemical sensors, based on lithium conducting solid-state electrolytes, are good candidates to fulfil these requirements and withstand the harsh chemical environment of the molten alloy. In this work, the synthesis and sintering conditions of the solid-state electrolyte Li6La3Ta1.5Y0.5O12 were optimized to obtain high-crystalline electrolyte pellets. XRD was used to verify the garnet structure needed for Li conduction. The quality of the sintering was evaluated using SEM-EDS and its ionic conductivity was measured using Electrochemical Impedance Spectroscopy (EIS) in argon, at temperatures between 30 °C and 200 °C. Finally, a lithium sensor was constructed and used in molten alloys. The obtained results were in good agreement with potentials calculated using the Nernst equation.