Oxygen and structure transformations of h-BN in focal zone of an optical furnace

Abstract

In this contribution the recent results on a synthesis of the new structures of boron nitride are presented. Light-induced catalyst-free heating of fine-grained graphite-like h-BN powders was performed in the flow of dried and purified nitrogen in an optical furnace. The new structures of boron nitride were obtained. Scanning electron microscopy JSM-6490 supplemented with combined Energy Dispersive X-ray Spectroscopy (EDS) and Electron Backscatter Diffraction (EBSD) provided information about structures, phase and element transformation of fine-grained graphite-like h-BN powders. The coarse structures, thread-like nanostructures (whiskers or dendritic structures) and new morphologies were formed due to the interaction of BN plume with nitrogen ambient on the surface of the heated compacted h-BN samples. Complicated structure and element composition of the whiskers which were formed on the surface of heated samples of compacted h-BN powders were studied by scanning electron microscopy (SEM). X-ray Diffraction (XRD) study demonstrates presence of amorphous phase, pure boron of different modifications and boron nitride of different phase compositions on the surface of these substrates. The process of the synthesis, formation and growth of the nanostructures in an optical furnace was analyzed and understood. A role of oxygen in formation and growth mechanism of BN whiskers was proposed.