Synthesis and Characterization of Alumina Powders Obtained at Various Temperatures Via Sol-Gel Method

Abstract

Alumina powders were synthesized by sol-gel method using aluminum isopropoxide as the precursor, de-ionized water as a solvent and hydrochloride acid as a gelation agent. The alumina gel has been dried and sintered at different temperatures in the range 200°C to 1200 °C. The synthesized samples were characterized by Termogravimetry analysis (TG/DTA), Fourier Transform Infrared Spectroscopy (FTIR), X-Ray diffraction (XRD), N2 adsorption / desorption techniques (BET) and Scanning Electron Microscopy (SEM). The X-ray diffraction diagrams showed the formation of different alumina’s phases such as ϒ-alumina obtained between 400°C and 900°C, θ-alumina at 1000°C and finally α-alumina was obtained at 1100°C. According to the calcination temperature, the crystallite size varies between 15.4 and 41.5nm. FT-IR confirmed the presence of hydroxyl groups and Al-O bonding vibrations, the specific surface area was found in the range of 74,939 and 156,3255 m2g-1, the pore diameter was in the range of 6,5579 to 9,4485nm and pore volume varies between of 0,082435 to 0,30514 cm3g-1depending as a function of heat treatment, and finally the SEM images reveal the formation of irregularly shaped particles with a disordered, heterogeneous structure. Likewise, thermal properties were investigated using the thermogravimetric method (TG) and differential thermal analysis (DTA), illustrating the thermal stability of the α-alumina phase at over 1100°C.