Role of copper on structural, magnetic and dielectric properties of nickel ferrite nano particles

• The crystallite size increases with Cu substitution and is found to be 6–12 nm.
• The inclusion of copper shifts the tetrahedral band to lower values.
• VSM results reveal that Ms and Mr decrease with increase in Cu concentration but Hc increases.

Copper doped nickel ferrites Ni(1−x)CuxFe2O4 (where x=0.2, 0.4, 0.6) nanoparticles are prepared by co-precipitation method and sintered at 600 °C. The XRD study confirms the formation of single-phase cubic spinel Ni–Cu ferrites. The particle size increases with Cu substitution. FT-IR spectra confirm the absorption bands around 554–547 cm−1 for the tetrahedral sites and around 448–450 cm−1 for the octahedral sites. The inclusion of copper shifts the tetrahedral band to lower values. The saturation magnetization (Ms) and remanent magnetization (Mr) decrease with increase in copper concentration and the coercivity (Hc) is found to increase for all the compositions sintered at 600 °C. The dielectric constant decreases drastically for all the compositions and reaches a constant value. These nanoparticles can be tested for humidity sensing applications.