Large-scale preparation of aluminum borate-coated aluminum oxide nanowires

Single-crystal and uniform aluminum borate (Al4B2O9)-coated aluminum oxide nanowires have been synthesized in high purity and in large yield via a reaction of metal aluminum with boron oxide in the presence of carbon nanotubes (CNTs). The aluminum oxide nanowires exhibit a well-crystallized one-dimensional structure with diameters ranging from 50 to 70 nm, and the Al4B2O9 have a coating thickness of about 1–5 nm. CNTs play a crucial role in the formation of the important ceramic nanowires, by providing a platform to grow the composite structure. The growth mechanism was proposed by the detailed microscopy observations.