Effect of variation in precipitating agents on the structural, optical, and antibacterial properties of Y₂O₃ nanoparticles

In the present study, yttrium oxide (Y₂O₃) nanoparticles were successfully synthesized using different precipitating agents, namely acetic acid, oxalic acid, sodium carbonate, and urea, through a controlled precipitation method. The crystalline structure and phase purity of the synthesized samples were examined by X-ray diffraction (XRD), confirming the formation of cubic Y₂O₃ with crystallite sizes ranging from 25 to 35 nm. Fourier transform infrared (FTIR) spectroscopy revealed the characteristic Y–O stretching vibrations in the 400–600 cm⁻¹ region, indicating the formation of Y₂O₃ and the absence of residual organic impurities. Morphological analysis using field emission scanning electron microscopy (FE-SEM) demonstrated well-dispersed nanoparticles, with particle size and morphology strongly dependent on the nature of the precipitating agent. The optical properties were investigated using UV–Vis absorption spectroscopy. The estimated optical band gap values ranged from 5.1 to 5.6 eV, showing precursor-dependent variations associated with differences in crystallinity and particle size. Raman spectroscopy further confirmed the cubic phase of Y₂O₃ through the prominent peak observed at approximately 375 cm⁻¹. Minor peak shifts were attributed to phonon confinement effects arising from nanoscale dimensions. The antibacterial activity of the synthesized Y₂O₃ nanoparticles was evaluated against Staphylococcus aureus (Gram-positive), Escherichia coli (Gram-negative), and Pseudomonas aeruginosa (Gram-negative). All samples exhibited measurable antibacterial efficacy, with acetic acid-derived Y₂O₃ demonstrating the highest inhibition zones (18 mm against S. aureus and 19 mm against E. coli). Comparative analysis indicated that Gram-positive bacteria were more susceptible than Gram-negative strains. Overall, the results demonstrate that the choice of precipitating agent significantly influences the crystallinity, morphology, and surface characteristics of Y₂O₃ nanoparticles, which in turn govern their optical behavior and antibacterial performance.