Impulse laser cutting of diamond accompanied by phase transitions to fullerene-type onions

Abstract

We studied a process of diamond cutting by a focused pulsed laser beam in an explosion inside solid matter mode (a 100 ns laser beam impulse focused in diamond generates a shock wave). A cavity size created in diamond by the laser impact is described by a conception of a blast cavity formation after explosion inside solid matter. Diamond cutting is also accompanied by a phase transition of diamond to fullerene-type onions composed of 2 to 5 shells. According to a new phase diagram of carbon (which contains a zone of diamond instability in the 55–115 GPa pressure range), the observed phase transition is possible under ~70 GPa pressure and ~2400 K temperature, which indicates pressure and temperature values during laser cutting. The pressure estimated based on the new phase diagram corresponds to the pressure estimated from the known blast cavity formation model.