R. A. Guirado-López
Instituto de Física “Manuel Sandoval Vallarta”, Universidad Autónoma de San Luis Potosí, Álvaro Obregón 64, 78000, San Luis Potosí, SLP, México
Abstract
In this work we report a combined experimental and theoretical study of boron nitride (BN) nanostructures synthesized by ball milling methodology. The BN nanostructures were obtained using h-BN powder under low vacuum conditions and steel balls of different sizes. The HRTEM images of our samples show the formation of spheroidal BN nanoparticles with diameters as small as ~7 nm which self-assemble into different hierarchical nanostructures such as two-dimensional layered materials, spheroidal configurations, and one-dimensional solid BN chains. The Raman spectra reveals an intense absorption band in the 300—600 cm-1 region, which is absent in the spectra of BN nanotubes, previously synthesized BN nanoparticles, as well as in all bulk boron-nitride polymorphs. Density functional theory calculations show that the Raman spectra is consistent with the formation of fullerene-like BN particles which also exhibit an intense absorption band in the 200—800 cm-1 range dominated by a complex mixture of tangential, stretching, and radial breathing modes. Finally, by means of electron-beam irradiation experiments additional structural transformations can be induce on our hierarchical BN particles consisting in the formation of nano-holes of the order of 5 nm. Our here-reported BN nanostructures might lead to a wide range of potential applications.
Keywords: boron nitride, ball milling, density functional theory
