Thermal-heating CVD synthesis of BN nanotubes from trimethyl borate and nitrogen gas

Boron nitride (BN) is one of III-V compounds widely applied on the electrical industry. It has been fabricated by numerous techniques, but so far there is no reliable method to produce pure and high-yielding BN nanotubes at relatively lower temperature. Therefore, the exploration on its synthesis is still a challenging subject. In the study, the BN nanotube would be synthesized by thermal-heating chemical vapor deposition (TH-CVD) with trimethyl borate evaporated at 60 deg. C and nitrogen gas flew into reaction chamber as the source of B and N, respectively. 434 stainless steel wires will be coiled as an entangled wire scaffold with pore size of 1 mm and then placed in the middle part of reaction chamber. The metallic ions contained in the stainless steel will serve as the catalysts for of BN nanotube in situ growth. From the results of SEM, HRTEM, FTIR and XRD analysis, hexagonal-BN (h-BN) and orthorhombic-BN (o-BN) nanotubes were successfully synthesized at relatively low temperature between 1000 and 1200 deg. C. All the nanotubes prepared in the system were identified as h-BN and o-BN. At reaction temperature of 1200 deg. C, several types of BN morphology appeared. The BN nanotubes could be obtained at the temperature between 1000 and 1100 deg. C. However, BN nanotubes for the latter temperature grow into larger size tube. The optimum reaction temperature for BN nanotube synthesis is 1000 deg. C. The reproduction property of synthesized BN nanotube by this method is very promising. The method should have a great potential to prepare BN nanotube in the future