Abstract
Surface nanostructure control is the key to functionalizing nanomaterials. This paper presents a characterization with thermodynamic stability analysis of CuCoMn1.75NiFe0.25 high-entropy alloy (HEA) nanoparticles synthesized by femtosecond laser ablation in ethanol and liquid nitrogen (LN2). Using multimodal electron microscopy and spectroscopy, we examine phase, particle size, defect structure, chemical distribution, and surface composition and relate them to HEA stability. Elemental distributions are uniform in both media, but LN2 produces smaller particles with a narrower size distribution and mainly single- or few-domain interiors, whereas ethanol yields larger particles built from 2–4 nm crystallites with domain aggregation. Edge defects appear in both but energy-dispersive X-ray spectroscopy (EDS) is broadly uniform with local fluctuations in ethanol. X-ray photoelectron spectroscopy (XPS), supported by an attenuation model, indicates an ∼1 nm oxide overlayer that suppresses Mn 2p intensity; correcting for it returns Mn toward the bulk value. UV–NIR and photoluminescent spectra independently support a thin oxide shell. Composition-based thermodynamic descriptors place LN2 closer to bulk mixing parameters, while ethanol raises ΔH_mix and lowers Ω. Cooling simulations are consistent (LN2 ∼ 0.1 μs quench, ethanol ∼1 μs). These results connect solvent-controlled kinetics and thermodynamics to crystalline state and surface chemistry, informing surface control of HEA nanoparticles.
| Original language | English |
|---|---|
| Pages (from-to) | 34173-34188 |
| Number of pages | 16 |
| Journal | Langmuir |
| Volume | 41 |
| Issue number | 50 |
| DOIs | |
| State | Published - Dec 23 2025 |
Funding
This work was supported by the University of Tennessee, Knoxville, through a hiring package. D.F. gratefully acknowledges the UTK 100 Talented PhD Scholarship. Atom Probe Tomography and Photoluminescence Spectroscopy research were conducted as part of a user project at the Center for Nanophase Materials Sciences (CNMS), which is a US Department of Energy, Office of Science User Facility at Oak Ridge National Laboratory. CNMS Proposal ID: CNMS2025-R-03093. We would also like to express our appreciation for the State of Tennessee and Tennessee Higher Education Commission (THEC) through their support of the Center for Material Processing (CMP). PKL very much appreciates the support from the National Science Foundation (DMR-2226508). The authors would like to thank Richard Haasch at the University of Illinois Urbana–Champaign for his contributions to data acquisition.