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

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.