Physical Characteristics of Stabilized Silver Nanoparticles Formed Using a New Thermal-Decomposition Method

Abstract

We decomposed a silver-fatty acid complex at 250 °C in a nitrogen atmosphere to make stable, mono-disperse silver nanoparticles. The size distribution was measured using high-resolution transmission electron microscopy (HRTEM); the mean particle diameter was 4.7 nm and the standard deviation was 0.6 nm. This size distribution was verified by the measured surface-plasmon absorption spectrum. Their X-ray diffraction pattern showed that they were metallic silver. Then we examined their internal structure using HRTEM. The particles cross-sectional shapes were usually circular except some were hexagons or pentagons. According to the HRTEM image, most particles were multiple twins; 18% were simple twins and 2% were single crystals. Use of thermogravimetry and differential thermal analysis showed that their surface was coated by fatty acid. This coating stabilized the nanoparticles thus preventing their aggregation even after repeatedly dissolving them in solvent and evaporating. However, the coating was easily removed by baking at 210 °C in one atmosphere of air.