First-principles-based surface phase diagram of fully relaxed binary alloy surfaces

Area of Science:

• Materials Science
• Computational Chemistry
• Surface Science

Background:

• Understanding binary alloy surface behavior is crucial for materials design.
• Predicting surface phase stability and atomic arrangements remains challenging.

Purpose of the Study:

• To develop a novel method for constructing density-functional theory (DFT)-based phase diagrams for binary alloy surfaces.
• To investigate the formation of cobalt (Co) antisite atoms at cobalt-aluminum (CoAl)(100) surfaces as a model system.

Main Methods:

• Utilizing density-functional theory (DFT) calculations with full geometric relaxation for binary alloy surfaces.
• Integrating concepts from statistical physics to build the DFT-based phase diagram.
• Employing low-energy electron diffraction (LEED) for experimental validation.

Main Results:

• Successfully constructed a DFT-based phase diagram for a binary alloy surface.
• Accurately predicted the appearance of Co antisite atoms at CoAl(100) surfaces.
• Demonstrated excellent agreement between calculated structural parameters (multilayer relaxations, surface buckling, lateral order, segregation profile) and experimental LEED data.

Conclusions:

• The combined DFT and statistical physics approach is effective for predicting binary alloy surface phase diagrams.
• The method accurately captures complex surface phenomena like antisite formation and structural relaxations.
• This approach provides a reliable tool for understanding and designing binary alloy surfaces.