Highlights

Structural and Compositional Study of Doped Boron Nitride Nanotubes

Scientific Achievement

Nanotubes are nanoscale materials with defect-free tubular structures even at their surfaces. Carbon nanotubes (CNTs) and boron nitride nanotubes (BNNTs) are well known to have this type of unique tubular structure.  However, BNNTs and CNTs are completely different in electronic and chemical properties.  The synthesis of BNNTs is now achievable only by a few research groups in the world, significantly more challenging than the growth of CNTs. In addition to their extraordinary structural and mechanical properties, BNNTs are having a bandgap of ~5.9 eV that is insensitive to tube diameter, number of walls, and chirality.  Theoretically, the band gap of BNNTs is tunable by doping of carbon. Due to these attractive properties, BNNTs are expected to be the complement the applications of CNTs.

This project has been performed for about six months at Michigan Technological University (MTU) and Argonne National Laboratory. At MTU, we have succeeded in the growth and doping of high-quality BNNTs by thermal chemical vapor deposition.  Within the first six months of the project, we have started in training a graduate student to analyze the structural and compositional properties of pure BNNTs by high-resolution transmission electron microscopy (HRTEM), and electron energy loss spectroscopy (EELS).  Preliminary data suggests that our pure BNNTs are having high structural orders.

In the next few months, we plan to extend our analysis to carbon doped-BNNTs at Argonne using HRTEM, EELS and energy-filtered imaging.  We hope to correlate the structural and compositional properties of BNNTs to their optical and electrical measurements to be performed at MTU.

Significance

There have been a few attempts on the doping of BNNTs. In general, there are several obstacles remained unsolved including, 1) phase separation between BN and carbon. 2) The optical and electronic properties of doped BNNTs have not been investigated.  In this project, we plan to understand the structural and compositional properties of our carbon-doped BNNTs.  In particular, we hope to understand the distribution and uniformity of carbon in BNNTs.  We will correlate this analysis to our growth process so as to achieve effective doping of BNNTs.  We will correlate the structural and compositional properties to the optical and electronic properties of doped BNNTs.

Performers