Microwave properties of chromium-substituted lithium ferrite

A structure characterization of chromium-substituted lithium ferrite specimens was carried out by the X-ray diffraction technique and found that the lattice parameter decreases with increasing of Cr-substitution content and the microstructure was determined by scanning electron microscopy (SEM), which revealed that the average grain size of chromium-substituted lithium ferrite decreases gradually with increasing Cr-substitution content. The magnetic moments calculated from Neelʹs molecular field model are in agreement in the experiment result, which indicates that the saturation magnetization decreases monotonically with increasing Cr-substitution content. The values of saturation magnetization (Ms) for Li0.5Fe1.5−xCrxO4 specimens decrease from 38.9 emu/g for x = 0.0 to 9.9 emu/g for x = 1.0. The microwave properties (complex permittivity and permeability) were measured in the 8–13 GHz frequency range by the cavity perturbation. The systematic variations of the real and imaginary parts of both permittivity and permeability with frequency and composition have been analyzed. The real and imaginary parts of both permittivity and permeability values decreased gradually with increasing frequency. The real part of permittivity ɛ′ values are found to vary in the range of 15.44–12.37, and the real part of permeability μ′ values are found to vary in the range of 3.95–1.27.