Excimer Laser Production, Assembly, Sintering, and Fragmentation of Novel Fullerene-like Permalloy Particles in Liquid

We report the fabrication of permalloy nanoparticles by pulsed excimer laser ablation of a permalloy (Fe 19 Ni 81 ) target in sodium dodecyl sulfate aqueous solution and the subsequent laser-induced assembly, sintering, and fragmentation of the nanoparticles. Specifically, permalloy nanoparticles with diameters of 400−600 nm were observed to assemble into fullerene-like hollow microparticles. Laser irradiation caused sintering of the assembled particles, which showed Wulff construction and ledge growth behavior and finally resulted in smooth shells. Laser−particle interactions also caused fragmentation of the micro/nanoparticles. When the particle concentration is high, laser fragmentation rather than laser ablation dominates due to enhanced light absorption and scattering. The experiments reveal the dynamic process of the nano- and microparticle formation, demonstrating the rich processing environment of laser ablation in liquid.