Al2O3 hollow nanospheres prepared by fluidized bed chemical vapor deposition and further heat treatment

Hollow-structured Al2O3 nanospheres were prepared by chemical vapor deposition (CVD) and further heat-treatment process. For the CVD process, a unique cooling gas loop was designed in the precursor delivery system and amorphous Al2O3 nanospheres with incomplete pyrolysis intermediated products were obtained in a vertical fluidized bed at 500celcius. The microstructure of the nanospheres tended to hollow after subsequent heat treatment at 1300celcius in air. It was found that the obtained Al2O3 hollow nanospheres showed a size of 100-450 nm in diameter and 20-80 nm in shell thickness. Transmission electron microscopy (TEM) and X-ray diffraction (XRD) analysis confirmed that the Al2O3 hollow nanospheres were alpha-Al2O3. The possible formation mechanism was proposed based on the results of the thermal gravimetric (TG) measurement connected with a Fourier transform infrared spectrometry (FTIR). The novel method to prepare Al2O3 hollow nanospheres can inspire ideas for the design and synthesis of other hollow-structured nanospheres.