Synthesis of continuous boron nitride nanofibers by solution coating electrospun template fibers

摘要

Continuous boron nitride nanofibers (BNNFs) have been synthesized from boric oxide (B203) coatings deposited on stabilized electrospun polyacrylonitrile fibers (S-PANFs). The B_2O_3 overcoatings were prepared by impregnating the S-PANFs with B_2O_3 ethanol solutions. By successive heat treatments at 800 °C in NH_3/O_2 mixture, 1100 °C in pure NH3, and 1500 °C in N_2, the S-PANFs were fully removed and the B_2O_3 coatings deflate to form solid fibers and transform into the BNNFs. The S-PANF template was fully removed by introducing O_2 during nitridation, and thus resulted in the formation of the BNNFs. The diameter of the BNNFs can be effectively controlled by changing the mass concentration of the B_2O_3 solution, and diameters from 43 to 230 nm were obtained by changing the B_2O_3 mass concentration from 0.25% to 4.8%. The obtained BNNFs are crystallized with the (002) planes oriented in parallel to the fiber axis. This method provides a powerful tool for obtaining BNNFs with controllable diameters, especially extremely thin BNNFs.