substituted superparamagnetic Mg[Fe.sub.2][O.sub.4] spinel-ferrites: Investigations on structural and spin-interactions

Nano-magnetic ferrites with composition [Mg.sub.1-x][Zn.sub.x][Fe.sub.2][O.sub.4] (x = 0.3, 0.4, 0.5, 0.6, and 0.7) have been prepared by coprecipitation method. X-ray diffraction (XRD) studies showed that the lattice parameter was found to increase from 8.402 to 8.424 [Angstrom] with [Zn.sup.2+] ion content from 0.3 to 0.7. Fourier transform infrared (FTIR) spectra revealed two prominent peaks corresponding to tetrahedral and octahedral at around 560 and 430 [cm.sup.-1] respectively that confirmed the spinel phase of the samples. Transmission electron microscopy (TEM) images showed that the particle size was noted to increase from 18 to 24 nm with an increase in Zn content from x = 0.3 to 0.7. The magnetic properties were studied by vibrating sample magnetometer (VSM) and electron paramagnetic resonance (EPR) which ascertained the superparamagnetic behavior of the samples and contribution of superexchange interactions. The maximum magnetization was found to vary from 23.80 to 32.78 emu/g that increased till x = 0.5 and decreased thereafter. Further, X-ray photoelectron spectroscopy (XPS) was employed to investigate the chemical composition and substantiate their oxidation states. Keywords: nanoparticles (NPs); nanospinel ferrites; structural properties; magnetism; coprecipitation method