Megahertz magneto-dielectric properties of nanosized NiZnCo ferrite from CTAB-assisted hydrothermal process

A simple hydrothermal route with cetyltrimethyl ammonium bromide (CTAB) was proposed for directly synthesizing single-crystalline NiZn ferrite at 160 °C. X-ray diffraction patterns and micrographs indicate that products consist of spinel ferrite nanogranulars. The dielectric constant of NiZnCo ferrite is about 11 and the imaginary part of complex permittivity is 1.3. The saturation magnetization (M_s) of NiZn ferrite improves from 0.041 to 0.074 A·m²/g for Ni_0.49Zn_0.5Co_0.01Fe_1.98O₄. The dielectric contant of NiZn ferrite increases from 7 to 11 with a cobalt stoichiometry of 0.01. The real part μ′ of complex permeability for NiZnCo ferrite reaches 3 at 1 GHz. The imaginary part μ′′ of NiZnCo ferrite has a value higher than 1.2 within 0.7?3.0 GHz. Through the incorporation of the magnetic fillers, the low dielectric constant of the composites may meet the requirements of impedance matching to achieve the maximal absorption of the electromagnetic energy in megahertz frequency range.