Enhancement of electrical and magnetic properties of Cd2+ doped Mn–Zn soft nanoferrites prepared by the sol–gel autocombustion method

Nanocrystalline Mn–Zn soft ferrites with chemical formula Mn0.5Zn0.5−xCdxFe2O4 (x=0.0–0.35) were synthesized using the sol–gel autocombustion method. The formation of single phase cubic spinel structure was confirmed from X-ray diffraction (XRD) pattern for all samples. The average crystallite size was calculated using Scherrer's formula and it remains within the range 24–50±2 nm. The structural parameters, lattice constant, XRD density, polaron length, polaron radius, lattice strain and porosity, have been calculated using XRD data. The variation in dielectric constant, dielectric loss tangent, AC conductivity and complex impedance analysis were studied in the frequency range from 20 Hz to 5 MHz at room temperature. The values of dielectric constant and loss tangent were found to be lowest for the concentration x=0.25. The high values of DC electrical resistivity (2.2×1011 Ω cm at 373 K) and activation energies suggests the conduction in Cd2+ doped Mn–Zn ferrite system is due to hopping of polarons. Complex impedance plane plots were used to separate the grain and grain boundary effects in Mn0.5Zn0.5−xCdxFe2O4. Vibrating sample magnetometer measurements carried out at room temperature shows that saturation magnetization and magnetic moment increased with increase in cadmium content up to x=0.25. The addition of Cd improves the magnetic and electrical properties of Mn–Zn ferrites.

► Sol–gel synthesis of Cd2+ doped Mn–Zn ferrites. ► Enhanced DC electrical resistivity due to cadmium. ► Increase in saturation magnetization with cadmium concentration. ► Impedance studies for the prepared samples.