Morphology dependence of radial elasticity in multiwalled boron nitride nanotubes

We report on the measurement of the radial modulus of boron nitride nanotubes (BN-NTs) with various sizes and thicknesses. These BN-NTs are radially much stiffer than previously reported thinner and smaller BN-NTs. Here, we show the key role of the morphology of the nanotubes in determining their radial rigidity; in particular, we find that the external and internal radii, R _ext and R _int, have a stronger influence on the radial modulus than the nanotube's thickness. The radial modulus decreases nonlinearly with 1/R _ext until reaching, for a large number of layers and a large radius, the transverse elastic modulus of bulk h-BN.