Investigation of the Physical Properties of Yb³⁺ Doped ZnFe₂O₄ Nanopowders Synthesized by Sol-Gel Method

ZnFe2-xYbxO4 with (x = 0, 0.01, 0.02, 0.03, 0.05, 0.07, and 0.09) have been successfully synthesized by the sol-gel method at 750°C. X-ray diffraction results showed a single phase and crystalline nanopowders of spinel-type structure with cubic symmetry and space group . The lattice parameters increase with Yb3+ concentrations. The BET specific area of ZnxFe2-xYbxO4 (x = 0.03) was determined to be the larger 13.59 m2/g. The crystallite size was determined by Rietveld to be in the range of 29-104 nm. FTIR spectra showed two strong absorption bands, a common characteristic of the spinel structure. Further, the shifting of the lower absorption band toward a higher frequency confirms that Yb3+ ions predominantly replaced Fe3+ ions in octahedral sites. The formation of the spinel phase in the samples was also validated by Raman scattering, with asymmetric broadening, and a systematic shift in the Raman spectra was observed as a function of Yb3+ concentration. Scanning electron microscopy SEM showed that powders consist of micrometric aggregation of smaller particles. EDS examinations verified that the chemical elements Zn, Fe, Yb, and O are present in all samples. The direct bandgap energy values are calculated by Tauc’s plot, and it indicates a semiconductor character of our compound, revealing an increase and enhancement in bandgap energy values from 1.82 to 2.4 eV with Yb3+ substitution.