Metallic Bond-Enabled Wetting Behavior at the Liquid Ga/CuGa₂ Interfaces

Area of Science:

• Materials Science
• Surface Science
• Physical Chemistry

Background:

• Interface interactions significantly influence material properties like contact angle and adsorption.
• Wetting phenomena at liquid metal (LM) and intermetallic interfaces are not fully understood.

Purpose of the Study:

• To investigate the wetting behavior of gallium-based liquid metals on CuGa2 surfaces.
• To elucidate the underlying mechanism of rapid spreading and puddle formation.
• To quantitatively evaluate interface forces using a theoretical model.

Main Methods:

• Density functional theory (DFT) calculations.
• First-principles calculations to determine work function, density of states, and adsorption energy.
• Development of a metallic bond-enabled wetting model.

Main Results:

• Gallium-based liquid metal droplets transform into puddles on CuGa2 surfaces.
• Formation of intermetallic CuGa2 on Cu surfaces induces stable metallic bonding and wetting.
• Calculated work function of CuGa2 (010) (4.47 eV) is comparable to liquid Ga (4.32 eV), facilitating electron exchange.
• Adsorption energy of Ga on CuGa2 is higher than In and Sn, indicating stronger interaction.
• Wetting force is proportional to gallium adatom adsorption energy and increases with gallium content.

Conclusions:

• Metallic bonding, driven by electron exchange and hybridization between Ga and CuGa2, is the primary cause of the observed wetting behavior.
• The established wetting model accurately predicts interface forces, showing good agreement with experimental data.
• Findings provide insights into the fundamental mechanisms governing liquid metal-intermetallic interactions.