Engineer in Situ Growth of α-Al₂O₃ Whiskers by Axial Screw Dislocations

Screw dislocation growth mechanism has recently drawn much attention in the micro/nanostructures due to its unique existence conditions and impact on the morphology. Here we reported the observation of a screw dislocation growth of single crystal α-Al 2 O 3 whiskers via a facile and novel in situ synthesis method. By programming synthesis temperatures, we observed an interesting circular to polygonal thread morphology transition on the surface of the as-synthesized α-Al 2 O 3 whiskers. Clear observations of the terraces and the axial dislocations under SEM and TEM characterizations revealed the presence of screw dislocation growth in the as-grown α-Al 2 O 3 whiskers. This mechanism was further validated by analyzing both the supersaturation of the system and the thermodynamics of chemical reaction in the system. This strategy provides a detailed understanding of the screw dislocation growth in the Al 2 O 3 whiskers as well as a new strategy for engineering Al 2 O 3 whiskers.