Influence of dysprosium substitution on the properties of cobalt-zinc ferrite nanoparticles: Structural, magnetic, and dielectric perspectives

Abstract

A hydrothermal synthesis approach was employed to fabricate Ni₀.₂₅Co₀.₅Zn₀.₂₅DyₓFe₂O₄ nanoparticles with Dy substitution levels of x = 0.000, 0.025, 0.050, 0.075, and 0.100. X-ray diffraction analysis confirmed a single-phase spinel structure, with average crystallite sizes decreasing from 32.98 nm in the undoped sample to 18.30 nm at the highest Dy content and a concomitant increase in interplanar spacing (d₍₃₁₁₎) from 0.2526 to 0.2554 nm. Specific surface area values rose from 36.38 to 65.56 m² g⁻¹. Williamson–Hall analysis estimated a crystallite size of approximately 12.81 nm and a microstrain of −0.00303, indicating lattice distortion due to Dy incorporation. Fourier-transform infrared spectroscopy revealed characteristic metal-oxygen stretching bands at ~588 cm⁻¹ (tetrahedral) and ~458 cm⁻¹ (octahedral), with slight shifts upon Dy doping. Magnetic measurements demonstrated superparamagnetic behavior with saturation magnetization values ranging from 34.7 to 40.8 emu g⁻¹, while dielectric analysis showed frequency-dependent permittivity, highlighting the potential of these materials for energy storage and magnetic applications.