Oxidation of thin film binary entropy alloys

In recent years, material science has put significant effort into understanding the behavior of multiple principle element alloys (MPEAs), notably the category high entropy alloys (HEAs). Most of these studies have been conducted on the micro to macro scales, yet the nanoscale remains relatively unexplored. Additionally, investigating the structural changes caused by amorphous oxidation for thin film MPEAs is particularly new, with no fundamental theory having been found. By studying ambient oxidation of thin film binary entropy alloys, we show how the Hume-Rothery rules affect the oxide formation and in particular the requirement of an increased temperature prior to the formation of polycrystalline oxides for these systems, compared to their single metal counterparts

Control of YH₃ formation and stability via hydrogen surface adsorption and desorption

Yttrium is known to form two hydrides: YH2, a metal, and YH3, which is dielectric. However, the stability of YH3 is not fully understood, especially in the context of thin films, where the yttrium layer must be coated to protect it from oxidation. In this work, we show that the stability of a YH3 thin film depends on the capping layer material. Our investigation reveals that YH3 appears to be stabilized by hydrogen that is adsorbed to the capping layer surface. This is evidenced by the YH3-YH2 transition temperature, which was found to be correlated with the desorption temperature of hydrogen from the surface. We posit that surface-adsorbed hydrogen prevents hydrogen from diffusing out of the thin film, which limits YH3 dissociation to the solubility of hydrogen in the YH2/YH3 thin film