Surface reaction of ZnO nanowires with electron-beam generated alumina vapor

Single-crystal ZnO nanowires are reacted at 800-900 degrees C in vacuum with alumina vapor generated by electron beam evaporation. The morphology changes after the solid-vapor reactions are studied in detail using electron microscopy and compared to other similar spine1 nanostructures. Unlike other solid-vapor reactions like MgO-Al2O3 and ZnO-Ga2O3 where a continuous spinel layer is formed, the reaction of ZnO nanowires with alumina vapor is unique. The initially smooth surfaces of ZnO nanowires become rugged due to surface decomposition without the growth of spinel layers. A formation mechanism is proposed that the surface reaction of ZnO with alumina vapor might constitute a process of a unilateral transport of ZnO and the associated surface diffusion.