Pure copper nanoparticles prepared by coating-assisted vapor phase synthesis without agglomeration.

Area of Science:

• Materials Science
• Nanotechnology
• Chemical Engineering

Background:

• Multilayer ceramic capacitors (MLCCs) are crucial for modern electronics like smartphones and electric vehicles.
• High-purity copper (Cu) terminations and nickel (Ni) electrodes are essential for MLCC performance.
• Vapor-phase synthesis (VPS) produces high-purity, crystalline nanoparticles (NPs) but often suffers from NP agglomeration.

Purpose of the Study:

• To develop a method to inhibit nanoparticle agglomeration during VPS.
• To improve the quality of Cu NPs for MLCC electrodes.

Main Methods:

• Utilized coating-assisted vapor-phase synthesis (VPS) with potassium chloride (KCl) as a coating agent.
• Synthesized Cu NPs via in-flight coating with KCl at 950 °C.
• Analyzed NP agglomeration ratio, purity, and crystallinity using X-ray fluorescence (XRF) and X-ray diffraction (XRD).
• Removed residual KCl and copper chloride using ammonium hydroxide washing.

Main Results:

• The agglomeration ratio of Cu NPs decreased dramatically from 48.20% to 3.80% with KCl coating.
• XRF and XRD confirmed the effectiveness of KCl coating in preventing agglomeration.
• Washing with ammonium hydroxide successfully removed the KCl coating agent and residual copper chloride, ensuring high material purity.

Conclusions:

• Coating-assisted VPS with KCl is an effective strategy to mitigate NP agglomeration.
• This method enhances the quality of Cu NPs for advanced electronic applications.
• The process ensures high purity of synthesized nanoparticles for MLCC electrodes.