Effect of interfacial mixed layer on hydrogen absorption in yttrium thin films

Abstract

Pd/Y bilayers and Pd/Ti/Y trilayers were prepared in a UHV chamber by DC/RF magnetron sputtering. The characterization of the Pd-Y and Ti-Y interfaces was performed immediately after the deposition using in-situ X-ray photoelectron spectroscopy (XPS). The results indicated significant interface mixing for the Pd/Y bilayers. Further studies showed that the additional Ti layer deposited between the palladium and yttrium layers can significantly reduce the mixing of the Pd-Y layers during the deposition process at room temperature, leading to the formation of a sharp Ti-Y interface. The structure of the obtained layers before and after the hydrogenation was examined by the standard X-ray diffraction method. The hydrogenation kinetics was studied in-situ at room temperature and pressure up to 1 bar using simultaneous measurements of resistivity and optical transmittance. It was found that for a thickness of Ti equal to 5 nm, the shortest transition time to the YH3 phase was obtained while maintaining a short switching time.