Tunable morphology of aluminum oxide whiskers grown by hydrothermal method

Hydrothermal method was used to grow α-Al2O3 whiskers by using hydrated aluminum sulfate, urea and poly ethylene glycol as precursors. X-ray diffraction (XRD), selected area electron diffraction (SAED), and high resolution transmission electron microscope (HRTEM) were used to characterize morphology of the whiskers. By increasing the pH of the solution (by adding extra NaOH), by adjusting calcination times and atmospheres it was possible to tune the whiskers morphology and their aspect ratio. Aspect ratio as high as 25 was obtained after hydrothermal treatment of a solution having pH 3 followed by calcination in Ar or N2 atmosphere at 1200 °C for 6 h.