Surface structures of In-Pd intermetallic compounds. II. A theoretical study.

Area of Science:

• Materials Science
• Surface Science
• Computational Chemistry

Background:

• Understanding intermetallic compounds and surface alloys is crucial for materials design.
• Indium-palladium (In-Pd) systems exhibit unique electronic and structural properties.
• Surface segregation and alloying behavior influence material performance.

Purpose of the Study:

• Investigate the surface properties of the InPd intermetallic compound (110) surface.
• Analyze the behavior of In-Pd surface alloys formed by burying indium-doped palladium layers in Pd(111).
• Determine the stability and segregation trends in these In-Pd systems.

Main Methods:

• Density Functional Theory (DFT) calculations.
• Projector Augmented Plane-Wave (PAW) method.
• Thermodynamic stability and segregation energy calculations.

Main Results:

• Surface segregation of indium is energetically unfavorable for stoichiometric InPd(110).
• Indium antisites segregate to the surface in off-stoichiometric InPd(110) systems.
• Stable In-Pd surface alloys are formed with indium concentrations below 50 at. %.
• In-doped Pd multilayers form at higher concentrations, with each layer below 50 at. % In.
• Stronger In-Pd bonding (-0.44 eV) compared to In-In (-0.29 eV) and Pd-Pd (-0.31 eV) explains alloying and segregation effects.

Conclusions:

• The study elucidates the complex surface segregation and alloying behavior of In-Pd systems.
• Computational findings provide insights into the formation of stable In-Pd surface alloys.
• Results highlight the critical role of indium concentration and bonding energetics in determining surface alloy stability.