Ultra-High Frequency Electromagnetic Waves Absorption of NiCoCuZn Ferrites

The sol-gel combustion method was used to create NiCoCuZn ferrites. The cubic spinel structure of the ferrites was confirmed using X-ray diffraction (XRD). With increasing cobalt doping concentration, the lattice parameter was found to increase. According to Scherrer’s formula, the crystallite sizes of the synthesized samples range from 30 to 54 nm. A field emission-scanning electron microscope (FE-SEM) was used for morphological studies. According to the magnetic hysteresis curves, as cobalt doping content increases, coercivity (
$H_{C}$
) increases from 24 to 366 Oe, and saturation magnetization (
$M_{S}$
) increases from 60 to 67 emu/g. The complex permittivity (
$\varepsilon ^{\ast } = \varepsilon ^{\prime }-i\varepsilon ^{\prime \prime }$
) and permeability spectra (
$\mu ^\ast = \mu ^{\prime }- i\,\,\mu ^{\prime \prime }$
) of ferrites were extracted from scattering parameters measured with a coaxial transmission line method from 0.001 to 3.6 GHz. Over a frequency of 0.001–3.6 GHz, the reflection loss (RL) of NiCoCuZn ferrites was studied by applying a magnetic field from 0.0 to 2.0 kOe. The value of RL and frequency of the maximum absorption increased with cobalt doping, whereas, with increasing the magnetic field, the frequency of the maximum absorption increased from 2.12 to 2.54 GHz, and the value of RL decreased from −42 to −28 dB.