Low temperature synthesis of nano alpha-alumina powder by two-step hydrolysis

• The nano α-Al2O3 with good dispersion was prepared by two-step hydrolysis.
• α-Al2O3 powders were added as seed particles in the hydrolysis.
• This article indicated that the glucose could impel the γ-Al2O3 transformed to α-Al2O3 directly.
• This article indicated that the addictive of α-Al2O3 seed could improve the phase transformation rate of γ-Al2O3 to α-Al2O3.
• In this article, the pure α-Al2O3 could be obtained by calcining at 1000 °C for 1.5 h.

The ultral fine alpha-alumina powder has been successfully synthesized via two-step hydrolysis of aluminum isopropoxide. Glucose and polyvinyl pyrrolidone were used as surfactants during the appropriate processing step. The alpha-alumina powder was used as seed particles. Several synthesis parameters, such as the amount of seeds, surfactants, and calcination temperature, were studied by X-ray diffraction (XRD), Fourier transform infrared spectra (FTIR), Thermogravimetry-differential scanning calorimetry (TG-DSC), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The experimental results showed that glucose greatly lower the phase transformation temperature of alpha-alumina by impelling the gamma-alumina transformed to alpha-alumina directly, and the seed could improve the phase transformation rate of alpha-alumina, the polyvinylpyrrolidone have an effect on preventing excessive grain growth and agglomeration of alpha-alumina powder. Comparatively well dispersed alpha-alumina powder with particle size less than 50 nm can be synthesized through this method after calcinations at 1000 °C for 2 h.

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