Fabrication of Nd3+ and Mn2+ ions Co-doped Spinal Strontium Nanoferrites for High Frequency Device Applications

Microemulsion method has been used for the synthesis of high resistive spinal nanoferrites with nominal composition Sr1-xNdxFe2-yMnyO4 (0.0 <= x <= 0.1, 0.0 <= y <= 1.0) for high frequency device applications. It has been confirmed by x-ray diffraction (XRD) results that these ferrites have a cubic spinal structure with a mean crystallite size ranging from 34 mm to 47 nm. The co-substitution of Nd3+ and Mn2+ ions was performed, and its effect on electrical, dielectric and impedance properties was analyzed employing direct current (DC) resistivity measurements, dielectric measurements and electrochemical impedance spectroscopy (EIS). The DC resistivity (rho) value was the highest for the composition Sr0.90Nd0.1FeMnO4, but for the same composition, dielectric parameters and alternating current (AC) conductivity showed their minimum values. In the lower frequency range, the magnitudes of dielectric parameters decrease with increasing frequency and show an almost independent frequency response at higher frequencies. Dielectric polarization has been employed to explain these results. It was inferred from the results of EIS that the conduction process in the studied ferrite materials is predominantly governed by grain boundary volume.