HomeDepartment of Physics, College of Science, Anbar University, Al-Anbar, Iraq
Journal of Optoelectronic and Biomedical Materials 2026, 18(3),1-13; https://doi.org/10.15251/JOBM.2026.183.1
Thin films of the spinel compound NiAl2O4 were synthesized using laser-assisted chemical bath deposition (LACBD). The effect of adding aluminum on the structural and electronic properties of the films was carefully studied. Nickel nitrate hexahydrate [Ni(NO3)2·6H2O] and aluminum nitrate nonahydrate [Al(NO3)3·9H2O] were used to fabricate nickel oxide (NiO) and aluminum oxide (Al2O3), respectively. The precursor solutions were mixed at different molar concentrations to synthesize thin films of NiAl2O4. X-ray diffraction (XRD), ultraviolet-visible (UV-Vis) spectroscopy, photoluminescence (PL), field-emission scanning electron microscopy (FESEM), and Raman spectroscopy were conducted to examine the films’ structure. XRD analysis indicated that the synthesized NiAl2O4 films displayed a polycrystalline cubic structure. Using Scherrer’s equation, the films’ crystallite size was calculated to be 115.5 nm. Optical measurements showed that the films let through about 77.4% of light in the 300-800 nm wavelength range. The optical bandgap was between 3.9 eV and 4.0 eV. FESEM analysis revealed that the average particle size decreased from ≈71 nm to 54 nm with the increase in Al2O3 concentration from 0.001 M to 0.01 M. The PL spectrum showed three strong emission peaks at 450, 640, and 850 nm. When aluminum was added, the peak at 640 nm disappeared and the overall intensity dropped. Raman spectroscopy confirmed the formation of the spinel NiAl2O4 phase through characteristic phonon modes in the range of 200-600 cm−1. Increasing Al2O3 incorporation altered local bonding and promoted partial spinel inversion, leading to reduced Raman intensity despite improved crystallinity, as verified by XRD and FESEM.
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