Subsurface synthesis and characterization of Ag nanoparticles embedded in MgO.

Area of Science:

• Materials Science
• Nanotechnology
• Surface Science

Background:

• Metal nanoparticles exhibit localized surface plasmon resonance (LSPR), sensitive to size, shape, and dielectric environment.
• LSPR causes field enhancement, making nanoparticles suitable for plasmonic applications like sensing.
• Partially exposed nanoparticles in a dielectric matrix are prime locations for LSPR spectroscopy.

Purpose of the Study:

• To synthesize and characterize a plasmonic substrate of silver (Ag) nanoparticles partially embedded in magnesium oxide (MgO).
• To investigate the evolution of nanoparticle morphology and size distribution with annealing.
• To prepare partially exposed Ag nanoparticles for LSPR-based sensing applications.

Main Methods:

• Synthesis of Ag nanoparticles in MgO via ion implantation and annealing.
• Characterization using micro X-ray diffraction (Micro-XRD), aberration-corrected transmission electron microscopy (TEM), and atom probe tomography (APT).
• Surface exposure of nanoparticles using plasma etching, followed by scanning electron microscopy (SEM) and atomic force microscopy (AFM).

Main Results:

• Ag nanoparticles evolved from spherical to faceted (octahedral) shapes with increased annealing time.
• TEM confirmed octahedral shapes truncated at (001) planes.
• APT verified the nanoparticles were pure metallic Ag.
• Plasma etching successfully exposed nanoparticles for surface analysis.

Conclusions:

• The synthesis method yields Ag nanoparticles within MgO with controllable morphology and size.
• Partially exposed Ag nanoparticles on MgO are promising for LSPR spectroscopy and sensing.
• The study demonstrates a pathway for creating tailored plasmonic substrates.