Temperature-Driven Morphological and Microstructural Changes of Gold Nanoparticles Prepared by Aggregation from the...

Area of Science:

• Materials Science
• Nanotechnology
• Surface Science

Background:

• Understanding the thermal stability of gold nanoparticles is crucial for their application in various fields.
• The behavior of thin gold films and nanoparticles is influenced by substrate interactions and processing conditions.

Purpose of the Study:

• To investigate the effects of annealing on thin gold layers and gold nanoparticles.
• To determine how substrate coverage and annealing temperature influence nanoparticle evolution and defect healing.

Main Methods:

• Statistically relevant X-ray scattering methods were employed.
• The study analyzed thin layers of gold and gold nanoparticles in air.

Main Results:

• Gold nanoparticle size increases via Ostwald ripening up to 450 °C, with decreasing defects.
• Above 450 °C, nanoparticles coalesce and spheroidize, especially on higher coverage samples.
• Defect healing in continuous gold layers occurs at lower temperatures than in nanoparticle layers.
• Nanoparticle layers show narrower size distributions than dewetted films.
• Gold crystal structure aligns with the substrate around 800 °C.
• Evaporation of smallest nanoparticles and hole formation in SiO2 observed above 1000 °C.

Conclusions:

• Nanoparticle behavior is highly dependent on substrate coverage and annealing temperature.
• Annealing promotes defect healing and size evolution, with distinct mechanisms for continuous films and nanoparticles.
• Significant structural transformations, including alignment and evaporation, occur at higher annealing temperatures.