Effects of annealing temperature on structural and magnetic properties of Ni0.8Zn0.2Fe2O4 thin films

Effects of annealing temperature on the structural and magnetic properties of Ni0.8Zn0.2Fe2O4 thin films on Si (100) substrates were investigated at room temperature by X-ray diffraction, atomic force microscopy, field emission scanning electron microscopy, a vibrating sample magnetometer and conversion electron Mössbauer spectroscopy. The thin films were prepared by a sol–gel spin-coating technique. It was observed that Ni0.8Zn0.2Fe2O4 thin films annealed at above 600 °C exhibited a single phase cubic spinel structure, and the lattice constant of ferrite thin films decreased monotonically from 0.8370 to 0.8346 nm. Their coercivity decreased from 14 to 11 kA/m when the average grain size increased from 47 to 172 nm by varying the annealing temperature from 600 to 900 °C, while their saturation magnetization increased from 433 to 544 kA/m. The study of Mössbauer spectroscopy showed that thin films were completely magnetically ordered. The isomer shift and the quadrupole splitting decreased with increasing annealing temperature while the hyperfine field increased. The change in the cation distribution of thin films was also discussed.