Study on Structural and Optical Properties of Nanocrystalline Mn–Ni Ferrites Prepared by Auto-Combustion Technique

Structural crystallinity and optical behavior of MgFe2O4 ferrite nanoparticles prepared by sol–gel method

Effect of synthesis routes on structural, optical, and electrochemical properties of Co3O4 nanoparticles

Electrical, Magnetic, Photocatalytic, and Structural Properties of Ni and Ce Substituted Magnesium Nano Ferrites: A Citrate Gel Auto-Combustion Approach

Effect of molar concentration of coprecipitating agent on the microstructural and optical properties of manganese ferrite nanoparticles

Cubic spinel ferrite nanoparticles manganese ferrite (MnFe2O4) are synthesized using the co-precipitation method. The structural parameters of all the samples have been studied through X-ray diffraction (XRD) patterns. Field effect scanning electron microscopy micrographs (FESEM) show the formation of highly dense forms of nanoparticles along with spherical morphology. But, at molarities of 1.3 M and 1.6 M, elongated particles were seen. The variation in bond distances with an increase in the molar concentration of NaOH could be attributed to more diffusion of Mn2+ ions and a deviation in the number of oxygen atoms in MnFe2O4. Raman spectra show that A1g band wavenumber shifts towards a higher wavenumber up to 1.3 M. This suggests an increase in bond length and lattice distortion, which is consistent with XRD results. Fourier transform infrared (FTIR) studies indicate that Mn2+ shifts from tetrahedral to octahedral site with an increase in molar concentration. FTIR results demonstrate that the molar concentration of NaOH significantly affects shape of nanoparticles, bond lengths, and amount of Mn2+ ions on the tetrahedral sites of MnFe2O4 nanoparticles.

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

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.

Structural, Optical and Dielectric Properties of Solvothermally Synthesized NiCo 2 O 4 Nanoparticles for Optoelectronic Applications

The solvothermal method was used to form Nickel Cobalt Oxide (NiCo 2 O 4 ) nanoparticles, which were then thoroughly characterized to assess the suitability for optoelectronic applications. A pure cubic inverse spinel phase with a mean crystallite size of 16 nm determined by Scherrer analysis was confirmed by X-ray diffraction (XRD). Phase purity was confirmed by Raman spectroscopy using distinctive Co–O and Ni–O vibrational modes at 495 cm −1 and 681 cm −1 , which correspond to the spinel structure’s F 2 g and A1g symmetry modes. Selected area electron diffraction (SAED) ring patterns produced an average particle size of 18.76 nm, which was in close agreement with the XRD result and high-resolution transmission electron microscopy (HRTEM) showed well-resolved lattice fringes confirming the high crystallinity of the nanoparticles. UV–Vis spectroscopy revealed strong visible-region absorption with a direct optical band gap of 2.03 eV, suggesting improved photon harvesting capability. Dielectric spectroscopy confirmed the material’s significant polarizability by showing frequency-dependent permittivity consistent with Maxwell-Wagner interfacial polarization, with the dielectric constant rising with temperature and falling with increasing frequency. NiCo 2 O 4 nanoparticles are a promising option for semiconductor and optoelectronic device applications due to their visible-range band gap, high polarizability, and nanoscale crystallinity.