Three-dimensional chemical imaging of embedded nanoparticles using atom probe tomography

Area of Science:

• Materials Science
• Nanotechnology
• Analytical Chemistry

Background:

• Analyzing embedded nanoparticles is challenging.
• In situ synthesis of gold (Au) nanoclusters in a single crystal magnesium oxide (MgO) matrix was performed using ion-beam implantation.

Purpose of the Study:

• To analyze the size and three-dimensional composition of Au nanoclusters embedded in an MgO matrix.
• To investigate the relationship between nanocluster size and gold concentration.

Main Methods:

• Laser-assisted atom probe tomography (APT) was the primary technique used for analysis.
• Scanning transmission electron microscopy and energy-dispersive spectroscopy (STEM-EDX) were employed for complementary analysis.

Main Results:

• Au nanoclusters synthesized in situ within the MgO matrix were successfully analyzed.
• Nanoparticle sizes were determined to be approximately 8-12 nm on average.
• APT provided detailed 3D compositional information, which is difficult to obtain with STEM-EDX alone.
• A correlation was observed where the maximum gold concentration within individual nanoclusters increased with their size, reaching up to 50% Au.

Conclusions:

• Laser-assisted atom probe tomography is a powerful technique for analyzing the 3D composition of nanoparticles embedded in matrices.
• The in situ synthesis method allows for controlled formation of Au nanoclusters in MgO.
• Gold concentration in Au nanoclusters is size-dependent, increasing with larger particle dimensions.