Magnetic and electromagnetic properties of composites of iron oxide and Co-B alloy prepared by chemical reduction

Magnetic and electromagnetic properties were investigated on the composites of iron oxide and Co-B alloy, which were prepared by a modified chemical reduction method. The composites are characterized by scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDXA), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and vibrating sample magnetometry (VSM). The complex electromagnetic parameters (permittivity epsilon(r)=epsilon(r)' + j epsilon(r)'' and permeability mu(r)=mu(r)' + j mu(r)'') of paraffin mixed composite samples (paraffin:composites 1:1 in mass ratio) were measured in the frequency range 2-18 GHz by vector network analyzer. The measured real part (epsilon(r)') and imaginary part (epsilon(r)'') of the relative permittivity show two resonant peaks in the range of 2-18 GHz. The imaginary parts of relative permeability (mu(r)'') of all samples exhibited one broad resonant peak over the 2-8 GHz range. The mu(r)'' of samples with higher molar ratio of Co to Fe (C and D) shows negative values within 13-18 GHz, which exhibit resonant and antiresonant permeabilities simultaneously. Calculation results indicated that the reflection loss values of the composites and paraffin wax mixtures are less than -10 dB with frequency width of about 6 GHz at the matching thickness. (C) 2010 Elsevier B.V. All rights reserved.