Effect of fluoride additives on production and characterization of nano-α-Al₂O₃ particles

Abstract

Nano- α-Al₂O₃ particles were synthesized by a sol–gel method using aqueous solutions of aluminum isopropoxide and 0⋅5 M aluminum nitrate. Sodium dodecylbenzenesulfonate (SDBS) was used as surfactant stabilizing agents. The solution was stirred for 48 h at 60 ^∘C. The microstructural observation showed that surfactant with 48 h stirring time nanoscale α-Al₂O₃ powder was produced at 1200 ^∘C in the range of 20–30 nm in the presence of SDBS as a surfactant with 48 h stirring time. Temperature reduction of α-Al₂O₃ formation has been achieved by introducing fluoride in the alumina precursor. The effects of ZnF₂ additive and milling on the phase transformation as well as micrograph of the prepared α-Al₂O₃ particles were investigated. The samples were characterized by different techniques such as X-ray diffraction, thermogravimetry analysis, differential scanning calorimetry, Fourier transform infrared spectra, scanning electron microscopy and transmission electron microscopy. Results indicated that using zinc fluoride (ZnF₂) additive accompanied by milling led to retardation of the transformation temperature and modification of the alumina particle shape. The finest size for nonagglomerated nano-plate-like α-Al₂O₃ particles (15–20 nm) was achieved at 950 ^∘C.