Effect of Laser Energies on the Performance of Exfoliation and Fragmentation for Hexagonal Boron Nitride by Laser

Abstract

A technique for exfoliating Boron nitride (BN) nanosheets was devised, which was then followed by a laser ablation-fragmentation process to produce lamellar hexagonal Boron nitride nanostructures (h-BNNs). The physicochemical properties of the nanoparticles were analyzed to investigate the effect of laser energy and wavelength in the two-step pre-treatment procedure during BN synthesis. The X-ray diffraction (XRD) patterns showed no impurity phase structures and only primary h-BN reflections were visible. It was discovered that the crystallite h-BNNs size ranged from 11 to 18 nm, and nanosecond laser energy was sufficient to transform BN into h-BNNs and a few nanotubes. Combining laser intensity and wavelength transformed the BN nanoparticle shape from haphazardly arranged platelets to melting-like formations. Fourier Transform infrared (FTIR) spectroscopy confirmed distinct observed changes in the size and melting behavior in the h-BNNs and the sharp absorption peaks which could indicate changes in their optical properties. Morphological characteristics and formation of the hexagonal phase of BN caused variations in optical properties and high-resolution transmission electron microscopy (HRTEM) results. Photoluminescence of h-BNNs was observed in the 250–600 nm range with peak emission at 485 nm. Due to its significant structural disorder, the h-BNNs exhibited a wide emission with a strong luminescence that remained largely continuous after 48 hours, resulting in a distinctive blue hue (470, and 485nm).