Abstract
Al doped Mn ferrite, MnAlxFe2-xO4 (x = 0.1, 0.2, & 0.3), nanoparticles were synthsized by facile and simple solution combustion route. Effect of Al3+ ions substitution on the structural, optical, electrical and magnetic properties were explored. X-Ray diffraction (XRD) results confirm the formation of pure cubic phase for all the synthesized nanoparticles having spinel structure. Various structural parameters like crystallite size, lattice parameter, site radii and bond lengths were estimated from XRD data. For the strain analysis and consideration of contribution of every peak in XRD data, W-H and N-R plots were analysed. Scannining electron microscopy (SEM) revealed the compact surface morphology with grain size in nano meter range. FTIR spectra confirmed the presence of metal stretching vibrations at tetrahedral and octahedral sites for all MnAlxFe2-xO4 nanoparticle compositions, which is typical of spinel ferrites with FCC structure. Raman spectroscopy helped in analysing metal stretching vibrations of the synthesized samples and obtained raman modes were found to be as predicted by group theory. Dielectric constant decreases with increase in frequency reflecting the normal behaviour of the ferrites. Dielectric loss also followed the same trend. Both the behaviours have been explained in view of Koop׳s theory and Maxwell–Wagner polarization-model. The synthesized ferrite samples exhibited the soft magnetic nature as confirmed by vibrating sample magnetometer. The room temperature hysteresis curves indicate the decrease in saturation magnetization as well as retentivity with the increase in Al3+ ions doping. The decrease in magnetic moment values have been explained on the basis of cation preference for the sites and also on weakening of exchange interaction upon aluminium doping.
•Al3+ substituted MnFe2O4 nanoferrites are synthesized for the first time by SC method.•Magnetic parameters suggest the utility for electromagnet application.•Low values of dielectric loss tangent are obtained.