Sorption properties and temperature-dependent near-surface chemistry of the BaLi4 intermetallic compound

BaLi 4 alloy has been analyzed using x-ray photoelectron spectroscopy and Ar+ ion depth profiling. A series of gases sorption tests have also been performed. The effects induced by room temperature (RT) gas exposure (air, N2, and O2) and vacuum annealing at low temperature (≈100 °C) have been studied in detail. High sorption capabilities are confirmed compared with previous works. Dosing the BaLi4 with N2 does not lead to appreciable change in the nitrogen surface concentration. However, its apparent concentration increases after repeated Ar+ sputtering, demonstrating the existence of a chemical reaction with the bulk alloy. This is shown to be in good agreement with N2 sorption tests carried out at RT on BaLi4 powder.