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

SURFACE SCIENCE

卷:640

Article

Boes, Jacob R.¹  Kondratyuk, Peter¹  Yin, Chunrong¹  Miller, James B.¹  Gellman, Andrew J.¹  Kitchin, John R.¹ 

[1] Carnegie Mellon Univ, Dept Chem Engn, Pittsburgh, PA 15213 USA

关键词: Composition spread alloy film;    Electron bacicscatter diffraction;    Density functional theory;    X-ray photoemission spectroscopy;    CuPd alloys;    Hydrogen purification;   

DOI  :  10.1016/j.susc.2015.02.011

来源: Elsevier

【 摘 要 】

CuPd alloys are important materials in hydrogen purification, where they are used as dense Pd-based separation membranes. Cu is added to impart sulfur tolerance and improved mechanical properties. At intermediate compositions and T<873 K, a BCC alloy (B2) phase occurs, which has superior separation characteristics to those of the FCC phases that form at high Cu and high Pd compositions. Identifying the composition and temperature 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 < x(pd) < 0.55 over which the B-2 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. (C) 2015 Elsevier B.V. All rights reserved.

【 授权许可】

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