Formation of δ-Al2O3 hollow nanoparticles via a chemical vapor condensation process

Aluminium oxide nanoparticles were synthesized by a chemical vapor condensation process using aluminium acetylacetonate as a precursor in the temperature range of 700 – 1000 °C. From X-ray diffraction results, it was found that the δ-Al phase was obtained at 900 °C and 1000 °C. Transmission electron microscopy observation revealed that δ-Al nanoparticles 10 – 15 nm in diameter consisted of a hollow structure with shells 2 – 3 nm in thickness. The sequential decomposition of acetylacetonate groups observed in thermogravimetry analysis showed that the formation of a hollow structure depends on the characteristics of the metal – organic precursor. Also, a decrease in the transmittance of δ-Al nanoparticles was found in the wavelength range of 300 – 900 nm by UV-Visible spectrophotometry, which is expected to occur by scattering and absorption of light depending on particle size and hollow structure.