Structural stability of a coaxial carbon nanotube inside a boron–nitride nanotube

The structural stability of a coaxial carbon nanotube inside a boron–nitride nanotube (C@BNNT) is investigated by molecular dynamics simulation. The geometric structures of armchair C(5,5)@BN(n,n) and zigzag C(9,0)@BN(m,0) nanotubes (n = 8–15; m = 15–22) are optimized by the density functional theory method using the DMol3 code. A comparison of the variation in the tube radius and analyses of the bind energy and radial distribution function show that the best BN(n,n) nanotubes for coupling with C(5,5) to form C(5,5)@BN(n,n) are BN(10,10), and the best BN(m,0) nanotubes for coupling with C(9,0) to form C(9,0)@BN(m,0) are BN(17,0) and BN(18,0). The optimal interwall distances between the inner C tube and the outer BN tube are about 0.35 nm for armchair and from 0.33 to 0.36 nm for zigzag nanotubes, respectively. The armchair C@BNNTs achieve a more stable combination structure than the zigzag case. Analyses of their energy and deformation electron density reveal that the interwall interaction between the inner carbon nanotube and outer boron–nitride nanotube is a van der Waals interaction.

Graphical abstractThe best BN(n,n) nanotube for coupling with C(5,5) to form C(5,5)@BN(n,n) is BN(10,10), and the best BN(m,0) nanotube for coupling with C(9,0) to form C(9,0)@BN(m,0) are BN(17,0) and BN(18,0). The armchair C@BNNTs achieves a more stable combination structure than the zigzag case.Figure optionsDownload full-size imageDownload as PowerPoint slideResearch highlights► The interwall interaction between inner CNT and outer BNNT is a typical van der Waals interaction. ► The optimal interwall distances for armchair and zigzag C@BNNTs have been obtained. ► The armchair C@BNNT achieves a more stable combination structure than the zigzag case. ► The study provides important research data for preparing a stable coaxial CNT@BNNT structure.