Annealing Effects on Semitransparent and Ferromagnetic ZnFe ₂ O ₄ Nanostructured Films by Sol–Gel

ZnFe 2 O 4 films have been prepared using a sol–gel route. The influences of annealing temperature as well as annealing atmosphere on the structural, morphological, magnetic, and optical properties were investigated. The TEM and SEM images show that ZnFe 2 O 4 films are polycrystalline in nature and homogeneous with densely packed grains. ZnFe 2 O 4 films exhibit ferromagnetic behavior at 300 K and high transparency (≥80%) above the absorption band edge. With decreasing annealing temperature and annealing oxygen partial pressure, the saturated magnetism at 300 K is improved and the optical band gap is decreased. The reasons are discussed, and the results show that semitransparent ZnFe 2 O 4 films with room‐ temperature ferromagnetism can be successfully prepared using a sol–gel method.