Synthesis and characterization of Fe₂O₃ nanoparticles via pulsed laser ablation in liquids: effects of solvent and laser fluence

In this study, the synthesis and characterization of iron (III) oxide (Fe₂O₃) nanoparticles using the pulsed laser ablation in liquids (PLAL) technique are reported. A 1064 nm Nd: YAG laser was used to ablate a hematite target immersed in different liquid media (acetone, ethanol, isopropanol, and bi-distilled water) under two distinct laser fluences (0.75 and 1.00 J/cm²). Fluence was varied by fixing spot size and changing the laser energy using the laser Q-switch delays, generating colloid with different stabilities within 4 min. The resulting nanoparticles were characterized by UV-Vis spectroscopy, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), selected area electron diffraction (SAED), and Raman spectroscopy. The UV-Vis spectra confirmed typical Fe₂O₃ absorption bands, with ethanol samples showing the highest absorbance and colloidal stability; all 4 samples presented a bandgap of ~ 2.8 eV. The unique presence of the P0 component at approximately 710.6 eV in XPS high-resolution spectra confirmed the exclusive presence of Fe³⁺ species in all samples. TEM images revealed spherical nanoparticles with diameters around 35 nm across all conditions. At the same time, SAED analyses identified a mixture of α- and γ-Fe₂O₃ phases. Raman spectroscopy confirmed the hematite phase's predominant presence, showing its characteristic signals near the 220, 298, and 400 cm^-1. The results indicate that within the fluence range explored, the choice of liquid medium does not significantly alter the stoichiometry or morphology of the synthesized nanoparticles. These findings support the versatility and scalability of PLAL for producing Fe₂O₃ nanoparticles tailored for various applications.