Synthesis and Physicochemical Property Analysis of Rare-Earth Ion Infused Nickel Oxide Nanorods: Combined Theoretical and Experimental Outcomes

Nickel oxide (NiO), a wide-band-gap semiconductor with high stability, is promising for optoelectronic and dielectric devices, yet its practical performance is often limited by moderate dielectric response and restricted light-matter interaction. Rare-earth doping offers a pathway to overcome these constraints by simultaneously tuning the structural, optical, and electrical properties. In this work, 1% erbium (Er)- and 1% gadolinium (Gd)-doped NiO nanoparticles were synthesized via a modified chemical route and comprehensively characterized. X-ray diffraction (XRD) confirmed the cubic nature of Er- and Gd-doped NiO, where Er incorporation reduced the crystallite and increased the surface area, facilitating interfacial polarization and an enhanced dielectric response. In contrast, Gd incorporation predominantly altered the electronic structure, narrowing the band gap and strengthening optical absorption. Field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) imaging confirmed uniform nanostructures, while Raman and X-ray photoelectron spectroscopy (XPS) analyses with Coats-Redfern kinetics indicated improved stability of doped samples. Optical investigations (UV-vis, PL) correlated band gap modulation with dielectric functions, validated through derived parameters such as the refractive index, optical dielectric constant, SELF, and VELF. Temperature-dependent dielectric studies demonstrated strong frequency dispersion linked to charge carrier dynamics originating from dopant-modified band structures. Thus, Er doping primarily boosts dielectric functionality through nanoscale polarization, while Gd doping optimizes optical transitions, together highlighting dopant-controlled correlations in NiO for multifunctional optoelectronic and energy-storage applications.