Tuning microstructural, optical and spin-related characteristics of pure NiO nanoparticles via (Fe, Al) co-doping

Abstract

In the present investigation, Fe and Al co-doped NiO nanocomposites were fabricated by chemical co-precipitation process using Polyvinylpyrrolidone (PVP) as a capping agent. The aluminium was fixed at 5 mol % and the iron concentration was varied from 1, 3 and 5 mol %. XRD coupled with the Williamson-Hall analysis confirm the formation of single phase cubic structure with mean size of crystallite was observed to be 38–25.2 nm. EDX results revealed the successful embedding of Fe and Al dopants into the NiO lattice. The XPS survey spectrum confirmed the presence of Ni, O, Fe, and Al, which authenticated the high purity and also the oxidation states of Ni2+, Fe3+, and Al3+ of the co-doped samples. The TEM images showed hexagonal-shaped nanostructure with a mean nanoparticle diameter of 22 nm. The DRS optical studies revealed that the optical energy gap dropped from 3.49 eV to 3.29 eV with raise of Fe concentration. The observed PL emission peaks at wavelengths 328, 375, 395, 422, 437, 457 and 468 nm, suggesting the presence of intrinsic defect states. The M-H loop analysis showed that the sample doped by 3 mol% of Fe had the highest value of magnetization, 14.9 × 102 0 μB/g. The simultaneous reduction in crystallite size, band gap narrowing, and enhanced ferromagnetic behavior demonstrates the synergistic effect of Fe and Al co-doping, indicating that these nanostructures are promising candidates for spintronic and optoelectronic applications.