Detection of CuAuPd Phase Boundaries Using Core Level Shifts

Area of Science:

• Materials Science
• Surface Science
• Solid State Chemistry

Background:

• Ternary alloys like Cu-Au-Pd are crucial in various applications.
• Understanding phase behavior in alloys is essential for material design.
• X-ray Photoemission Spectroscopy (XPS) is a powerful surface-sensitive technique.

Purpose of the Study:

• To investigate the electronic structure of Cu-Au-Pd alloys using XPS.
• To correlate core level binding energy shifts with alloy composition and phase.
• To develop XPS as a method for phase mapping in complex alloys.

Main Methods:

• High-throughput synthesis of a continuous composition spread alloy film (CSAF) of Cu_xAu_yPd_1-x-y.
• Acquisition and analysis of X-ray photoemission spectra for Cu 2p_3/2, Au 4f_7/2, and Pd 3d_3/2 core levels.
• Correlation of core level shifts with crystallographic phases (FCC and B2).

Main Results:

• All constituent elements (Cu, Au, Pd) showed core level binding energy shifts in the alloy compared to pure elements.
• The Cu 2p_3/2 core level shift exhibited discontinuities corresponding to FCC-B2 phase transitions.
• The B2 phase extent was successfully mapped across the ternary Cu_xAu_yPd_1-x-y composition space.

Conclusions:

• Core level binding energy shifts are sensitive indicators of phase transitions in alloys.
• XPS can be effectively used to map alloy phases, particularly in the B2 phase of Cu-Au-Pd.
• This XPS-based phase mapping approach is applicable to various material morphologies, including nanoparticles and thin films, where diffraction methods are limited.