Comparison of sol-gel and co-precipitation methods on the structural properties and phase transformation of γ and α-Al2O3 nanoparticles

The nanostructured γ and α alumina powders were synthesized by sol-gel and co-precipitation methods, and properties of the powders were studied by XRD, SEM, TEM, BET and FTIR. The results showed that both γ and α phases were formed in the lower temperature in precipitation method compared to sol-gel. The size of spherical α-alumina synthesized by sol-gel was 10–15 nm, whereas the sample prepared by co-precipitation yielded nearly spherical and hexagon α-powder with particle size of 10–50 nm. At 750 °C the resulting powder prepared by co-precipitation exhibited larger surface area (206.2 m2/g) compared to sol-gel (30.72 m2/g), hence it is recommended for catalytic and sensing applications.