Controlled synthesis of boron nitride (BN) coating on Al4B2O9 nanowhiskers

BN-coated aluminum borate (Al4B2O9) nanowhiskers with a uniform diameter of ~20 nm have been successfully synthesized by sol–gel and post-thermal-treatment methods. Al4B2O9 precursor is prepared under a relatively low temperature then heat treated at higher temperatures. By controlling heat-treatment conditions, BN is favorably generated in the form of uniform coating on the surface of Al4B2O9 as illustrated by SEM and TEM observations. Owing to inertness, the BN layers improve the high-temperature stability of Al4B2O9, which is verified by XRD and SEM characterizations. The successful synthesis of the uniform fine BN-coated Al4B2O9 nanowhisker is of significance and has the potential to expand the commercial value of aluminum borate nanowhiskers.