Strong correlation between Dy3+ concentration, structure, magnetic and microwave properties of the [Ni0.5Co0.5](DyxFe2-x)O-4 nanosized ferrites

Abstract

The dysprosium ions (Dy-3(+))-substituted nanosized ferrites (NFs) of composition [Ni0.5Co0.5](DyxFe2-x)O-4 (x <= 0.08) were prepared using the citrate gel process. To analyse the magnetic properties of the samples, the Mossbauer spectroscopy methods and vibrating sample magnetometry (VSM) were applied. The room temperature Mossbauer spectra were fitted to determine the hyperfine parameters of the proposed NFs. The preferential occupation of the octahedral B sites by the Dy3+ in the spinel ferrite sublattice was confirmed from the cations distribution. The hyperfine magnetic field of both sublattice decreased whereas the increase in the Dy3+ substitution was observed. The S-parameters of the prepared NFs in the high frequency range were measured by the co-axial method. In addition, the MW reflection losses were evaluated by means of the frequency-dependent (in the range of 1-20 GHz) complex permittivity and permeability spectra. All the NFs indicated that the absorption of the electromagnetic radiation was ranging between 2.9-5.5 GHz due to the natural ferromagnetic resonance. A correlation amongst the Dy3+ concentration, microstructure, magnetic and microwave (MW) characteristics of these NFs was established. It's been asserted that by controlling the Dy3+ contents carefully, the MW absorption and magnetic attributes of the proposed spinel NFs can be tailored. (C) 2020 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.