In situ FTIR investigation on phase transformations in BN nanoparticles

Fourier transformation infrared spectrum (FTIR) was employed to investigate phase transformation of nanoparticle BN, containing eBN, rBN, wBN and cBN, in which eBN and rBN are the main components. We found that part of eBN was converted into rBN at 200–350°C. At and above 400°C, eBN transformed into wBN, and some of wBN were converted into cBN simultaneously. This conclusion is supported by the results from high-resolution transmission electron microscopic (HRTEM) and Raman spectroscopic measurements. In this work, the converting processes between different BN phases were continuously monitored by in situ FTIR spectroscopy. The results will be helpful for synthesis of cBN at moderate conditions.