Synthesis of Electromagnetic Wave-Absorbing Co-Ni Alloys and Co-Ni Core-Shell Structured Nanoparticles

Area of Science:

• Materials Science
• Nanotechnology
• Electromagnetics

Background:

• Cobalt-nickel (Co-Ni) alloy nanoparticles are promising for microwave absorption.
• Controlling alloy formation is key to optimizing properties.

Purpose of the Study:

• To synthesize Co-Ni alloy nanoparticles with tunable compositions.
• To investigate their microwave absorption properties.
• To understand the formation mechanism of Co-Ni alloys.

Main Methods:

• Synthesis using oleylamine as a complexing agent and 1-heptanol as a reducing solvent.
• Time-resolved sampling, in situ X-ray absorption spectroscopy (XAS), and UV-vis spectrophotometry for mechanism elucidation.
• Free-space method with a vector network analyzer for microwave absorption measurements.

Main Results:

• Successfully synthesized Co-Ni alloy nanoparticles by controlling reduction timing.
• Demonstrated superior microwave absorption (Reflection Loss of -25.7 dB at 13.6 GHz) for alloy structures compared to core-shell.
• Confirmed synthesis of various Co-Ni alloy compositions.

Conclusions:

• The developed method enables controlled synthesis of Co-Ni alloys with enhanced microwave absorption properties.
• Oleylamine complexation is crucial for facilitating Co-Ni alloy formation.
• These alloys represent a significant advancement in microwave absorption materials.