Synthesis of molybdenum nitride γ-Mo2N by multipulse laser irradiation of molybdenum in nitrogen

The γ-Mo2N phase has been synthesized by multipulse laser irradiation of molybdenum foils in pure nitrogen atmosphere. The optical plume emissions produced on the laser irradiation were identified with various atomic, ionic and molecular species present. The obtained molybdenum nitrides were analyzed and characterized by scanning electron microscopy, X-ray diffraction and Auger electron spectroscopy. The formation of the molybdenum nitrides results from a nitridation reaction through a molten phase, and it seems that nitrogen activation and Mo surface heating and melting by the laser irradiation are responsible for the efficient incorporation of nitrogen in the Mo lattice and the creation of MoN bonds. It is also found that laser heating and melting and laser-induced shock waves give rise to a densification of the nitride layer microstructure.