1. Introduction
After its successful experimental realization [1], carbon nanotubes (CNTs) have stimulated tremendous interest in the extraordinary properties of nanotubular structures [2]. Recently, boron nitride nanotubes (BNNTs), which are structurally similar to CNTs, have attracted increasing attention [3–8]. BNNTs were theoretically predicted [9] in 1994 and successfully synthesized in 1995 [10]. Compared with metallic or semiconducting CNTs, BNNTs are all stable wide band gap semiconductors independent of their helicity and diameter, regardless of whether the nanotube is single-walled or multi-walled [8]. In addition, BNNTs possess high chemical stability, excellent mechanical properties, and high thermal conductivity [5]. Thus, BNNTs are expected to be a promising nanomaterial in a variety of potential fields such as nano-devices, functional composites, and electrically insulating substrates [5,11].