Structural, optical and magnetic properties of Y-doped NiFe2O4 nanoparticles prepared by simple co-precipitation method

Undoped and Y-doped NiFe2O4 nanoparticles were successfully synthesized by the simple co-precipitation method without any organic gelation agent. The appropriate annealing temperature and time to obtain single-phase spinel NiFe2-xYxO4 (x = 0, 0.05, 0.1, and 0.15) is 800 degrees C for 1 h. The particle size measured from scanning electron microscope (SEM) and transmission electron microscope (TEM) images confirms the nanostructural character in the range of 20-40 nm. The crystallite size (D-XRD = 27.54-17.43 nm) decreased while the cubic lattice parameters (a = 8.2981-8.3510 angstrom) increased as the Y3+ content in nickel ferrite spinel increased. Undoped and Y-doped NiFe2O4 nanoparticles have strong optical absorption in the UV (lambda = 200-400 nm) and visible (lambda = 400-600 nm) ranges, together with significantly lower band gap energy (E-g) compared to the NiFe2O4 materials synthesized by the sol-gel and hydrothermal methods (E-g = 1.57-1.67 eV). All the undoped and Y-doped NiFe2O4 samples exhibited strong ferromagnetic behaviour with narrow magnetic hysteresis loop and high magnetization. An increase in the doped Y3+ ion in the NiFe2O4 spinel crystal lattice reduced the saturation magnetization (M-s = 84.33-28.25 emu/g) while at the same time increasing the coercivity (H-c = 69.74-23.46 Oe) and remanent magnetization of the obtained materials (M-r = 84.33-28.25 emu/g). In this manners, Y-doped NiFe2O4 nanopowders, with a narrow band gap and strong ferromagnetic behaviour, can be used as catalysts for photochemical reactions, as well as materials for transformer cores, magnetic conductors, and gas sensors.

Automated summary

Undoped and Y-doped NiFe2O4 nanoparticles were successfully synthesized. The appropriate annealing temperature and time to obtain single-phase spinel NiFe2-xYxO4 is 800 degrees C for 1 h. The samples demonstrated strong optical absorption in the UV and visible ranges, as well as strong ferromagnetic behavior.