Nanosecond Pulse Laser Heating of Graphite in DAC

Abstract

Laser heating with nanosecond pulses was performed in DAC for the first time. The heated graphite transforms to a transparentdiamond-like state at pressures up to 35 GPa as follows from the micro-Raman studies. The scanning transmission electron microscopy (STEM) analysis shows the heated material is intermediate between the sp² and sp³ materials. Other observed phenomena are connected with ablation. Spherical droplets and nanocrystals were found at the surface as a product of condensation of the evaporated carbon. Possibly nitrogen (high-pressure medium) reacts with the species of ablated carbon. STEM analysis showed the incorporation of nitrogen in the heated sample.