Correlation between chemical composition, electrical, magnetic and microwave properties in Dy-substituted Ni-Cu-Zn ferrites

Highlights: • Nanostructured Dy-substituted Ni-Cu-Zn spinel ferrites were produced via sol-gel method. • Strong correlation between Dy concentration, magnetic and microwave properties was observed. • Control of the microwave properties can be used for functional radio electronics. Dy³⁺ ion-substituted nanoferrites Ni_0.4Cu_0.2Zn_0.4Fe_2−xDy_xO₄ (x ≤ 0.04) were produced via sol-gel method. Correlation between chemical composition, crystal structure, electrical, magnetic and microwave properties was investigated. All samples were characterized by single-phase state. It was observed that the increase of the Dy content leads to a decrease in the average crystallite size. The bandgap (E_g) was deduced to be between 1.83 and 1.86 eV. The measurements of magnetization versus applied magnetic field (M-H) and magnetization versus temperature (M-T) were investigated by vibrating sample magnetometer (VSM). Magnetic measurements revealed superparamagnetic character at room temperature. The magnetization was increased initially with doping Dy³⁺ in the ratio of x = 0.01 compering to the un-doped sample and thereafter dropped as Dy³⁺ ions content further increases. Microwave properties were discussed in terms of electromagnetic absorption in the frequency range 1–20 GHz. The occurrences of the intensive electromagnetic absorption in the frequency ranged from 1.6 to 2.7 GHz were observed. The changes in the amplitude-frequency characteristics correlated well with the level of chemical substitution (x) with Dy ions concentration.