Synthesis of amorphous metallic nanoparticles using a laser ablation process

Amorphous metals have been discovered in 1960 and, because of their structures, exhibit very unique mechanical, magnetic and chemical properties that can have various applications. These properties qualify them as the potential material of the future. This work focuses on a new laser ablation technique to synthesize nanoparticles of amorphous metals from aqueous feedstock. One of the critical factors in the production of amorphous metal is the cooling rate used to synthesize them. The laser ablation of microparticle aerosol (LAMA) process used in this work, with a cooling rate estimated of 10¹² K/s, has all the characteristics required for the production of such metallic glasses. A Collison nebulizer is used to generate microdroplets of a nitrate solution containing the corresponding ratio of metals for the production of a Zr-Al-Ni based alloy. Once dried and conditioned, these microdroplets leave solid microparticles which are ablated by an excimer laser producing nanoparticles that are then filtered by virtual impaction. In order to characterize the nanoparticles obtained with this process nanoparticulate films produced by LAMA have been analyzed by optical profilometry, scanning electron microscopy (SEM) equipped with energy-dispersive x-ray spectroscopy (EDS) and transmission electron microscopy (TEM) equipped with EDS. The results agree with a hypothesis that the films contain oxidized, amorphous metal on the surface of the films. When the films are thin, they are fully oxidized, and simultaneous segregation of Zr occurs to the surface. The hypothesis and the results are discussed.