Cerium oxide (ceria, CeO₂) nanoparticles were successfully synthesized in the present work using the co-precipitation (CPT) method with potassium carbonate and cerium tri-nitrate hexahydrate as precursor solutions. The preparation involved controlled precipitation followed by aging and thermal treatment to enhance crystallinity. The obtained powder was then gently ground and calcined at two different temperatures, 700 °C and 850 °C, for three hours each to examine the effect of thermal treatment on structural, vibrational, and morphological properties. A set of analytical techniques, including X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), and field-emission scanning electron microscopy (FE-SEM), were employed to evaluate the crystalline phase formation, chemical composition, and microstructural characteristics of the ceria NPs. XRD analysis confirmed that the synthesized samples crystallize in a single-phase cubic fluorite structure without any secondary phases or impurities. The calculated lattice parameters were 5.392 Å for the sample calcined at 700 °C and 5.357 Å for the sample calcined at 850 °C, demonstrating a slight reduction in lattice parameter with increasing calcination temperature. Chemical composition analysis via EDS verified the presence of cerium (Ce) and oxygen (O), thereby confirming the successful formation of CeO₂ without contamination. FE-SEM micrographs revealed that the ceria NPs exhibit a predominantly spherical morphology with uniform size distribution. Mild agglomeration was observed, which is typical for nanoparticles due to high surface energy and interparticle attractive forces. The crystalline, high-purity Ceria NPs produced in this work possess desirable structural and morphological attributes that make them promising candidates for advanced functional applications including catalysis, fuel cells, optical devices, and environmental remediation.

Keywords: Cerium(IV) Oxide Nanoparticles; Co-Precipitation; Gas Sensor; Nanocrystal;