Gallium-assisted growth of flute-like MgO nanotubes,Ga2O3-filled MgOnanotubes, and MgO/Ga2O3 co-axial nanotubes

Abstract

Flute-like MgO nanotubes were successfully synthesized via a simple thermal evaporation method byusing Mg3N2 and Ga2O3 as the source materials. The nanotubes are single-crystal cubic MgO, and have [100]orientation. In contrast to conventional nanotubes with intact walls, the flute-likeMgO nanotubes possess a unique porous structure. On the nanotubes there areseries of holes aligned along the nanotube length with approximate equidistance.Ga2O3-filled MgOnanotubes and MgO/Ga2O3 co-axial nanotubes were also found in the product. Further investigation confirms that the innerβ-Ga2O3 has an epitaxial growth relation with the outer MgO nanotube due to their perfect latticematching. A gallium-assisted growth mechanism was proposed to interpret the growth ofthe flute-like MgO nanotubes. The thermal expansion and evaporation of the filled liquidgallium in MgO nanotubes are likely responsible for the formation of the hole structures onthe side walls.