Growth mechanism and ultraviolet-visible property of novel thick-walled boron nitride nanostructures

Abstract

A novel kind of high quality thick-walled BN nano-tadpoles was successfully synthesized through an effective catalytic chemical vapor deposition combined with a co-precipitation method using Na₂SiO₃·9H₂O, Mg(NO₃)₂·6H₂O and amorphous boron powders as raw materials. SEM, FSEM, EDX, TEM, HRTEM, SAED, XRD, FTIR and Raman spectroscopy were employed for the characterization of the morphology, composition, structure and bonding features of the as-synthesized BN samples. The as-synthesized BN nano-tadpoles revealed a length of 10–15 μm and homogeneously tapered diameter from the head to the tail of the BN tadpole. The head diameter of every BN nano-tadpole was 0.5–1.5 μm and the tail diameter was less than 50 nm. Besides, ultraviolet-visible absorption spectroscopy indicated that the as-synthesized BN nano-tadpoles present a different band gap (5.39 eV) compared with that of BN nanotubes and hBN. Moreover, on the basis of the experimental results, the possible chemical reactions and the base vapor–liquid–solid (VLS) and diffusion association growth mechanism are also proposed to properly interpret the formation of the thick-walled BN nano-tadpoles.