Core level shifts in Cu–Pd alloys as a function of bulk composition and structure

article i nfo Available online xxxx Composition spread alloy film Electron backscatter diffraction Density functional theory X-ray photoemission spectroscopy CuPd alloys Hydrogen purification CuPd alloys are important materials in hydrogen purification, where they are used as dense Pd-based separation membranes.Cuisaddedtoimpartsulfurtoleranceandimprovedmechanicalproperties.Atintermediate compo- sitions and T b 873 K, a BCC alloy (B2) phase occurs, which has superior separation characteristics to those of the FCCphasesthatformathighCuandhighPdcompositions.Identifying thecompositionandtemperature window where the B2 phase forms is a critical need to enable the design of improved alloys. A composition spread alloy film of Cu and Pd was synthesized. The film was characterized by electron back scatter diffraction and X-ray photoelectron spectroscopy, providing the core level shifts as a function of bulk composition and bulk structure. An anomalous deviation in the Cu core level shift was observed in the composition range 0.33 b xPd b 0.55 over which the B2 phase occurs. Density functional theory calculations were used to simulate core level shifts in the FCC and B2 alloy structures. They suggest that the anomalous deviation in core level shift is due to formation of the ordered B2 phase in this composition range.