Investigation into the structural and magnetic features of nickel doped U-type hexaferrites prepared through sol–gel method

This paper reports the impacts of nickel substitution on dielectric, magnetic, and structural characteristics of Ba4Cu2-xNixFe36O60 hexaferrites prepared via the sol–gel method. The sample was annealed for 5 h at 1200 °C. The crystalline structure, magnetic and dielectric features were examined by X-ray diffraction, vibrating sample magnetometer, and impedance analyzer individually. The specific absorption bands of hexagonal ferrites were identified by FTIR spectroscopy and in the 420–600 cm−1 range. M−H loops of samples were determined to examine the magnetic properties of synthesized materials. Magnetic measurement shows that samples exhibit ferrimagnetic behavior at room temperature. The magnetic properties are described in cation distribution and grain size effect. Dielectric properties of the samples were observed in the frequency range (1–3 GHz). Cole-Cole graphs of prepared materials revealed the influence of grain boundaries. A single semi-circle in the impedance Cole-Cole plots approves a special part of grain boundaries in the conduction process. Dielectric properties are affected by the electron hopping mechanism between Fe2+ and Fe3+ ions. These performances expose that these nanomaterials are appropriate for high-frequency applications.