Fabrication of Single‐Crystal α‐Al 2 O 3 Nanorods by Displacement Reactions

Nanometer‐sized Al 2 O 3 rods are fabricated by sintering a powder mixture of Al and SiO 2 . The sintered product is leached in HF–HNO 3 solution, followed by rinsing and washing before the nanorods are collected. The yield of the product is about 50 wt%. Transmission electron microscopy reveals that these rods are 1 to 2 μm long and have a diameter of 20 to 100 nm, while electron diffraction confirms that these rods are single crystals of α‐Al 2 O 3 . It is observed that these rods have either round or slightly sharp tips, which is different from those having droplet‐like tips that are usually found in products fabricated by catalytic reactions.