Relation of structure and magnetic properties in nickel substituted MgFe2O4

This study presents the structure-related magnetic properties of nickel substituted MgFe_2−xNi_xO₄ with x=0.01-0.20, synthesized using thermal decomposition of metal organic starting materials. The samples were annealed at temperatures ranging from 900 to 1100 °C in air. Magnetic and electric properties were characterized using vibrating sample magnetometer and an impedance analyzer, respectively. The fraction of inverse spinel structure was found to decrease with increase in nickel concentration. The samples exhibited soft magnetic behavior. The magnetization was found to depend on the substitution of Ni atoms on the octahedral sites and on the average number of valence electrons. The dielectric properties were found to have higher values at low frequency and decreased with increase in frequency. An enhancement of the dielectric constant was observed upon increase in the annealing temperature.