Influence of composition variation on structural, magnetic and dielectric properties of Gd3Fe5O12(x)/MgFe2O4(1-x) composite

Sol-gel auto-combustion method was used to prepare Gd3Fe5O12 and MgFe2O4. Mechanical blending was used to form the composites of Gd3Fe5O12 (x)-MgFe2O4 (1-x) (x = 1.0, 0.5, 0.75 in wt.%). X-ray diffraction (XRD) study reveals the pure phase formation of Gd3Fe5O12 and MgFe2O4 and the presence of both phases in composites. The average crystallite size lies in the range of 26-56 nm. Field emission scanning electron microscope (FESEM) study reveals that the grains of Gd3Fe5O12 have a spherical morphology and its composites show agglomeration due to presence of magnetic interaction between ferrites nanoparticles. The dielectric study reveals that the real and imaginary parts of complex permittivity of the composites vary with the change in the composition of Gd3Fe5O12 and MgFe2O4. For x = 0.5, the low dielectric tangent loss (tan delta) similar to 0.35 with high dielectric constant (epsilon ') similar to 612 was obtained at 1 MHz frequency. This suggests the use of these composites for dielectric substrate antennas. Further, the magnetic property reveals that the magnetic parameter of Gd3Fe5O12 composites varies by addition of MgFe2O4, i.e. at x = 0.5 and 0.75. The values of microwave operating frequency (omega(m)) are 3.5 GHz and 2.5 GHz for x = 0.5 and x = 0.75, respectively. These values suggest that the composites can be used in S-band.