PNNL

Abstract

Periodic mesoporous hexagonal boron nitride was investigated as a precursor for nanoscale forms of cubic boron nitride. Cubic boron nitride (c-BN) nanocrystals were obtained at a pressure of 14 GPa and a temperature of 13008C. The synthesized nanocrystals have diameters of ~ 50 nm and are solution processible. Mesoporous c-BN formed at a pressure of 10 GPa and 1000 8C. The mesoporous c-BN has a pore size distribution centered around 3 nm and a surface area of 122 m2/g as determined by electron tomography. At pressures of 8 and 6 GPa near monodisperse h-BN nanodiscs with diameters of 0.5-1 mm and 0.2-0.5 mm were formed, respectively. The discs formed colloidal solutions in acetone. The hydrodynamic radius of the discs matched the radii determined by dynamic light scattering indicating absence of nanodisc aggregation in solution.