Cation Distribution Assisted Tuning of Magnetization in Nanosized Magnesium Ferrite

Abstract

The MgFe 2 O 4 nanoparticles are synthesized by combustion method and annealed at different temperatures from 500 to 1000 C. Magnetic properties, morphology, valence states of iron, crystal structure, and microstructure of the samples are investigated systematically by vibrating sample magnetometer, field emission scanning electron microscope, transmission electron microscopy, X-ray absorption spectroscopy, and synchrotron X-ray diffraction. Cation distribution is determined from synchrotron X-ray diffraction data using Rietveld refinement combined with extended X-ray absorption fine structure spectroscopy. The results indicates that all the samples are phasepure with crystallite size ranging from 11 to 41 nm. By adjusting the annealing temperature, cation distribution and particle size can be changed, and consequently leading to the change in structure and magnetic properties. The saturation magnetization of the samples are enhanced significantly compared to that of the bulk material. The variation of magnetic properties is discussed based on cation distribution, particle size, valence state, surface effect, and spin canting.

Annealing Temperature Effects on Humidity Sensor Properties for Mg0.5W0.5Fe2O4 Spinel Ferrite

“…According to the literature on the substitution of Mg metallic ions with other metallic ions [ 42 , 43 ], it seems that tungsten metallic ions favor ferrite formation at an annealing temperature of below 1050 °C. The X-ray diffraction results of the magnesium-tungsten spinel ferrite, i.e., concerning reflections on lattice planes, are in accordance with other reported data on the preparation of magnesium ferrite [ 44 , 45 , 46 , 47 ].…”

Breaking the Stoichiometric Limit in Oxygen-Carrying Capacity of Fe-Based Oxygen Carriers for Chemical Looping Combustion using the Mg-Fe-O Solid Solution System

“…The peak with R > 3 Å is assigned to the scattering pair between a tetrahedral Fe center and a corner-sharing octahedral center in the spinel structure, in which at least one of the metal centers is Fe 3+ or Fe 2+ . 38 For 3M1F-R, the two main EXAFS peaks at 1.7 and 2.5 Å could be ascribed to the Fe−O bonds of the FeO 6 octahedra and the Fe−Fe/Mg distance between neighboring octahedra in the halite solid solution, respectively, similar to that of the FeO reference. Fitting of the EXAFS data (Figure S8) suggests that occupancies of 1/3 and 2/3 for the tetrahedral (A) and octahedral (B) sites by Fe, respectively (Table S5), could explain the EXAFS data well, in close agreement with the Mossbauer spectroscopy and XPS results.…”

“…The characteristic peaks of the spinel structure can be seen for 3M1F, 3M1F-100C, and the Fe 3 O 4 reference: the first peak near 1.5 Å is assigned to the Fe A –O and Fe B –O bonds; the second peak at ∼2.6 Å corresponds to the first iron–metal shell (Fe B –M B ), where the Fe and the metal belong to two edge-sharing octahedra. The peak with R > 3 Å is assigned to the scattering pair between a tetrahedral Fe center and a corner-sharing octahedral center in the spinel structure, in which at least one of the metal centers is Fe 3+ or Fe 2+ . For 3M1F-R, the two main EXAFS peaks at 1.7 and 2.5 Å could be ascribed to the Fe–O bonds of the FeO 6 octahedra and the Fe–Fe/Mg distance between neighboring octahedra in the halite solid solution, respectively, similar to that of the FeO reference.…”

Specific Loss Power of Co/Li/Zn-Mixed Ferrite Powders for Magnetic Hyperthermia

“…Together with the chemical composition changes, the manipulation of the cation distribution on octahedral and tetrahedral sites represents another suitable strategy to control the magnetic behavior of ferrites due to the strong connection between the spinel structure and its magnetism [44][45][46][47].…”