Thermal conductivity of B–C–N and BN nanotubes

We have measured the temperature-dependent thermal conductivity κ(T) of boron–carbon–nitride (B–C–N) and boron nitride (BN) nanotube mats between room temperature and 20K. For both materials, κ(T) increases with increasing temperature, with no sign of saturation. We employ an analysis method to estimate the intrinsic κ(T) of BN nanotubes converted from B–C–N nanotubes, and find that at room temperature κ(T) of a multiwalled BN nanotube can be comparable to that of a multiwalled carbon nanotube and may exceed it if made isotopically pure. At low temperature, the functional form of κ(T) reflects dimensional confinement.