Effect of magnesium substitution on dielectric and magnetic properties of Ni–Zn ferrite

The dielectric and magnetic properties of Mg incorporated Ni–Zn spinel ferrites have been investigated. Ni0.5−xZn0.5MgxFe2O4 ferrites have been prepared by sol–gel auto-combustion technique. The as prepared ferrites were annealed at 673, 873 and 1073 K. The X-ray diffraction studies reveal the spinel structure of annealed ferrites. The TEM results are in agreement with XRD results. FTIR study has also been carried out to get insight into the structure of these ferrites. The dielectric measurements show that the dielectric constant (ε′), dielectric loss (tan δ) and conductivity (σac) increase on incorporation of Mg in the Ni–Zn ferrite. ε′, tan δ and σac also show dependence on temperature, frequency of external applied electric field and microstructure of the samples. The magnetic moment measurements reveal that the saturation magnetization (Ms) increases and coercivity (Hc) decreases with the increase in concentration of Mg2+ ions. Ms and Hc also show dependence on the annealing temperature.

Research Highlights
► Ni0.5−xZn0.5MgxFe2O4 spinel ferrites have been synthesized by sol–gel auto combustion technique.
► The crystallite size increases with increase in the concentration of Mg2+ ions.
► The values dielectric constant, dielectric loss and ac conductivity increase with increase in the concentration of Mg2+ ions.
► Saturation magnetization first increases and then decreases with increase in the concentration of Mg2+ ions.
► The values of coercivity decrease with increase in Mg2+ concentration.