Generation of Size-Controlled Crystalline CeO₂ Particles by Pulsed Laser Irradiation in Water

The defining characteristics of nanoparticles (NPs) include variation of properties as a function of size and shape, requiring their preparation with desirable dimensions and morphologies. Here, a unique approach based on pulsed laser irradiation in liquid (PLIL) was developed to reshape commercial CeO₂ NPs suspended in water in an attempt to respond to these challenges. Guided by the results of Mie theory and the predictions of the heating-melting-evaporation model, the fourth harmonic of an Nd:YAG laser (266 nm, 10 Hz, 5 ns) was selected and used for lateral irradiation of colloidal CeO₂ samples at particular laser fluences and number of laser pulses for producing size- and shape-specific crystalline NPs. Spectral and structural analyses of the NPs, prior to and following PLIL, revealed shape and crystal size alterations depending on the irradiation parameters, affecting melting, evaporation, and solidification of the particles. The change in size, shape, and agglomeration could be followed by the results of the analyses, where the first two could be also interpreted by the modeling results. This study demonstrates that controlled CeO₂ crystal particles, from nano- to submicrometer diameters, could be generated by PLIL, shedding new light on the dynamics of the process.