Structural evolution of hexagonal boron nitride powder by Bead-milling

The structural evolution of h-BN powder by bead-milling is investigated. A unique initial stage in h-BN milling is discovered in which the x-ray diffraction (XRD) out-of-plane (0 0 2) and (0 0 4) peak intensities increase distinctly up to 3 and 4.8 times respectively, corresponding to an effective c-axis ordering of the h-BN particles. The structural evolution of h-BN due to milling is correlated to the change in the dominant milling mechanism from out-of-plane cleaving to in-plane cutting. An abnormal contraction of out-of-plane (0 0 2) interplanar spacing up to 0.044 A due to bead-milling is reported, which could be attributed to the introduction of oxygen functional groups (B-O and N-O) on the h-BN powder.