Impact of doping Gd3+rare earth ion on structural, magnetic, and optical properties of cobalt and nickel ferrite nanomaterials

The impact of Gd rare earth ion on structural, magnetic, and optical properties of Ni and Co spinel ferrite nanomaterial prepared by low-cost sol–gel method has been studied in this research. The XRD measurement confirms the pure phase formation having crystallite size between 15.61–23.49 and 12.01–30.95 nm for Gd3+substituted CoFe2O4 and NiFe2O4, respectively. A slight decrement in crystallite size was found due to large size ion of rare earth elements. The lattice constants of CoFe2O4 materials displayed a decrease from 8.4477 to 8.3635 Å and an increase from 8.3565 to 8.3968 Å in NiFe2O4 materials, prepared at the same temperature. The molecular bonds between 469 and 3453 cm−1 were examined by FTIR spectroscopy. The direct bandgap (Eg) of CoFe2O4 and NiFe2O4 was between 1.63–2.41 and 1.61–1.66 eV, respectively, by UV–Visible spectroscopy. The room temperature PL studies (200 nm excitation) revealed a dominant blue emission and a weak green emission. The particle size of CoFe2O4 and NiFe2O4 was found 34 and 41.58 nm, respectively, by HRTEM which is close to the result obtained by XRD analysis. The coercivity (Hc) of pure CoFe2O4 and NiFe2O4displayed the magnitude of 1452.41 and 191.49 Oe, respectively. The saturation magnetization (Ms) was found between 30.59–57.84 and 23.99–42.11 emu/g for CoFe2O4 and NiFe2O4. The tuned optical and magnetic behavior could make them applicable in magneto-optical devices, water purification and other related uses.