Synthesis and characterization of GaxLiᵧ alloys with various lithium compositions

Abstract

An optimized vacuum-based technology for synthesizing Ga–Li alloys with controlled lithium content ranging from 10 to 50 at.% was developed and experimentally validated. The process combines two-stage lithium purification (chemical treatment and vacuum distillation) with high-temperature homogenization under residual pressure ≤10⁻⁵ Pa, ensuring low contamination levels and precise stoichiometry control. Comprehensive characterization using SEM, XRD (ICDD PDF-4+), DSC (25–500 °C), and ICP-MS demonstrates the formation of thermodynamically stable intermetallic phases Ga₇Li₂ and Ga₉Li₅ in the near-stoichiometric composition region. The observed phase assemblage is governed by equilibrium thermodynamics rather than kinetic limitations, as confirmed by the absence of metastable phases and the consistency between XRD and DSC results. Distinct endothermic transitions at ∼320 °C and ∼388 °C are attributed to transformations associated with Ga₇Li₂ and Ga₉Li₅ phases, respectively, in agreement with the equilibrium Ga–Li phase diagram. The synthesized alloys exhibit high compositional accuracy (deviation ≤0.6 at.%) and microstructural homogeneity, confirming the effectiveness of the developed synthesis route. A key finding is the experimentally confirmed reduction in lithium thermodynamic activity, leading to a decrease in saturated vapor pressure by 3–4 orders of magnitude compared to pure lithium in the temperature range 400–500 °C. This effect is highly important for fusion applications, as it suppresses lithium evaporation and improves compatibility with structural materials. The developed synthesis methodology and the obtained structure–property relationships demonstrate that Ga–Li intermetallic alloys are promising candidates for liquid metal plasma-facing components and tritium-related systems in next-generation fusion reactors.