Structural and electromagnetic studies of Mg1-xZnxFe2O4 nanoparticles synthesized via a sucrose autocombustion route

Abstract

Mg1−xZnxFe2O4 nanocrystalline ferrites (1.0 ≥ x ≥ 0.0) were prepared using a sucrose autocombustion-assisted route. X-ray diffraction (XRD) showed secondary phase formation at Zn contents higher than x = 0.2. The obvious increase in the lattice parameters from 8.3937 to 8.4454 A upon increasing the Zn content might be attributed to the ionic radius of Zn2+ ions being larger than that of Mg2+ ions. The crystallite sizes calculated using Scherrer’s formula confirmed the nanocrystalline nature of the prepared samples. The Fourier-transform infrared (FTIR) spectra exhibited characteristic ferrite bands attributed to tetrahedral and octahedral sites, and there was an obvious splitting in the tetrahedral absorption band attributed to the Jahn–Teller distortion effect. Transmission electron microscopy (TEM) images showed agglomerated spherical particles with sizes that are in full agreement with results obtained by XRD. A reliable cation distribution was suggested based on the obtained structural parameters to address the preferential occupation of the entirety of the cations with increasing Zn content. The magnetic parameters estimated by vibrating sample magnetometer (VSM) measurements were utilized to confirm the suggested cation distribution and address the effect of Zn substitution on the entire system. All the investigated samples, except for ZnFe2O4, exhibited soft ferromagnetic characteristics. The obtained coercivities were higher than those reported in the literature and suggested the presence of an elevated demagnetization field and reflected the impact of the present synthesis method. The AC conductivity indicated semiconducting properties, and there was a ferromagnetic-to-paramagnetic magnetic transition in all samples with increasing temperature. The dielectric measurements also confirmed this transition by exhibiting relaxations in the same temperature range.