CoNiCuCrS alloy nanoparticles: synthesis and atomically resolved T/STEM studies.

Area of Science:

• Materials Science
• Nanotechnology
• Solid State Chemistry

Background:

• High entropy alloys (HEAs) are advanced materials with complex compositions offering unique properties.
• Understanding atomic-scale behavior, including strain distribution and defects, is crucial for optimizing HEA performance.
• Characterizing bulk HEAs at the atomic level presents significant experimental challenges.

Purpose of the Study:

• To synthesize and characterize CoNiCuCrS nanoparticle alloys.
• To investigate atomic-scale strain distribution and crystal structure using advanced microscopy.
• To explore the role of defects and sulphur in the mechanical properties of HEAs.

Main Methods:

• Synthesis of CoNiCuCrS nanoparticle alloys.
• Characterization using scanning transmission electron microscopy (STEM) at atomic resolution.
• Analysis of crystal structure, lattice parameters, and strain distribution.

Main Results:

• Hexagonal platelets of CoNiCuCrS nanoparticles with an average size of 34.5 nm were synthesized.
• Atomic resolution STEM revealed an ordered FCC crystal structure, consistent with a (CuCo)₆Ni₃Cr₁S_13.333 intermetallic phase.
• Direct experimental evidence of atomic-scale strain distribution and the role of sulphur-stabilized defects (stacking faults, partial dislocations) was obtained.

Conclusions:

• Nanoparticle alloys provide a viable model system for studying bulk high entropy alloys (HEAs) at the atomic scale.
• The study confirmed the presence of significant local strains in HEAs.
• Sulphur-stabilized defects significantly influence the mechanical properties of these HEAs.