Structural evolution of hollow Al2O3 particles formed on excimer laser-induced bubbles

Pulsed laser ablation of Al in aqueous solutions could generate hollow Al2O3 particles due to laser-induced bubbles, but the generation depends on the laser wavelength. Herein, the structural evolution of amorphous and hollow Al2O3 spheres produced by 248 nm laser ablation in water–ethanol mixture has been studied. The amorphous phase could crystallize into γ-Al2O3 by thermal annealing while maintaining the shell structure. The 248 nm laser-induced photodissociation of water and ethanol could aid the formation and increase the lifetimes of bubbles, which are critical for the formation of hollow particles.