Elemental (im-)miscibility determines phase formation of multinary nanoparticles co-sputtered in ionic liquids

Area of Science:

• Materials Science
• Nanotechnology
• Physical Chemistry

Background:

• Non-equilibrium synthesis enables alloying of immiscible elements into nanoparticles, expanding material design possibilities.
• Sputtering on solid substrates creates solid solutions, but its efficacy for nanoparticles in ionic liquids remains unclear.

Purpose of the Study:

• Investigate sputtering in ionic liquids for synthesizing nanoparticles of immiscible elements.
• Determine if Hume-Rothery rules are applicable to sputtered nanoparticles.
• Understand nanoparticle formation in ionic liquids.

Main Methods:

• Co-sputtering of Au-Cu (miscible), Au-Ru, Cu-Ru (immiscible), and Au-Cu-Ru systems onto the ionic liquid [Bmim][(Tf)2N].
• Analysis of nanoparticle characteristics, including size and composition.
• Atomistic simulations using density-functional theory for cluster stability.

Main Results:

• Nanoparticles from immiscible elements were larger (3.3–5.0 nm) than those from miscible pairs (1.7–1.8 nm).
• Immiscible combinations yielded compositions dominated by one element (e.g., Cu94Ru6), unlike miscible ones.
• Experimental and theoretical results confirmed miscibility/immiscibility govern thermodynamic stability.

Conclusions:

• Sputtering in ionic liquids can produce alloy nanoparticles from immiscible elements.
• Nanoparticle size and composition are dictated by elemental miscibility.
• A formation model for multinary nanoparticles in ionic liquids was developed based on experimental and simulation data.