Zn1−xNixFe2O4 ferrites up to x = 1.0 with Δx = 0.2 have been synthesized via solid state reactions and the sol–gel autocombustion technique with step-by-step co-firing. Data on the chemical composition and the surface morphology of the samples have been obtained using a scanning electron microscope. An X-ray powder diffractometer has been used to establish the phase purity and to determine the unit cell parameters. It has been found that the obtained samples had a spinel structure with the Fdm (No. 227) space group. The unit cell parameters decrease with increasing nickel concentration. The a unit cell parameter decreases almost linearly from ∼8.443 A for x = 0.0 down to ∼8.337 A for x = 1.0. The V unit cell volume decreases almost linearly from ∼601.72 A3 for x = 0.0 down to ∼579.52 A3 for x = 1.0. The magnetic characteristics of the obtained samples are determined and discussed. The Curie point of obtained samples varies in the range of 803.5–572.7 K. The maximum spontaneous magnetization of ∼74.6 emu g−1 at room temperature was fixed for the solid solution with x = 0.6. Ac-resistivity drops by more than 3 orders of magnitude in the frequency range 1–106 Hz. The composition with x = 0.6 has the minimum ac-resistivity of 5.3 kOm cm at a frequency of 106 Hz. The maximum value of the (μ′) real part of ∼11.2 and (μ′′) imaginary part of ∼5.2 of the permeability in the frequency range of 50 MHz–10 GHz is observed for the composition with x = 0.4. The composite samples for the microwave study were prepared by mixing of the ferrite powders with molten paraffin wax. The volume fraction of the ferrite filler in the composites was 25%. The largest value of the (μ′) real part of ∼3 and (μ′′) imaginary part of ∼0.63 of permeability is found for the x = 0.4 composite. The formation of the composite significantly reduces permeability.

Ni substitution effect on the structure, magnetization, resistivity and permeability of zinc ferrites

Structural and photocatalytic properties of new rare earth La3+ substituted MnFe2O4 ferrite nanoparticles

Synthesis of MnFe2O4@graphene oxide catalyst for biodiesel production from waste edible oil

Structural modifications in Co–Zn nanoferrites by Gd substitution triggering to dielectric and gas sensing applications

Rare-earth doped Ni–Co ferrites synthesized by Pechini method: Cation distribution and high temperature magnetic studies

Nanocrystalline Gd3+-doped Co–Mg ferrite nanoparticles with the chemical formula Co0.7Mg0.3Fe(2−x)GdxO4 (x = 0.02) were prepared by coprecipitation for the first time. The properties of the nanoparticles were investigated by X-ray diffraction, confirming a single-phase, highly crystalline cubic spinel structure in the space group Fdm and an average crystallite size of 54 nm. The Fourier-transform infrared spectrum showed two fundamental absorption bands in the wavenumber range of 437–748 cm−1 attributed to the stretching vibration of tetrahedral and octahedral sites in the spinel structure. Scanning electron microscopy analysis showed that the nanoparticles are different in shape and slightly agglomerated. Energy-dispersive X-ray spectroscopy demonstrated the purity of the nano-ferrite powder. Magnetic measurements revealed ferrimagnetic behavior at room and low temperatures with high coercivity and a high saturation magnetization of 95.68 emu g−1, larger than that of pure bulk cobalt ferrite (80.8 emu g−1). Only ferrite cobalt synthesized sonochemically has been reported to have a higher saturation magnetization (92.5 emu g−1).

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Magnetic and structural properties of single-phase Gd3+-substituted Co–Mg ferrite nanoparticles

In this paper, rare-earth doped M-type strontium hexaferrite magnetic nanoparticles SrHoxGdySmzFe(12−(x+z+y))O19 (x = y = z = 0.01) have been prepared by the sol–gel combustion method for the first time. The properties of the material were investigated using XRD, FTIR spectroscopy, Raman spectroscopy, SEM, UV-Vis spectroscopy, and VSM. X-ray analysis revealed that a magnetic single-phase was formed with a crystallite average size of 49 nm. FTIR spectra confirmed the formation of the structure of the hexaferrite phase. Raman analysis confirmed the formation of all crystallographic hexaferrite sites. A shift in the octahedral site frequencies and a significant shift were observed at site 12k and 2a, indicating that the doping elements occupied these sites. The SEM analysis showed that the particles were different in shape and slightly agglomerated. The EDS result confirmed the purity of the sample. The calculated band gap from the UV-Vis NIR spectroscopy spectra of the sample was 1.62 eV. The magnetic analysis of the sample material at room temperature revealed a coercivity of 5257.63 Oe, saturation magnetization of 67.72 emu g−1, remanence ratio of 0.52, a maximum magnetic energy product of 1.06 MGOe and Curie temperature of Tc = 765 K. First-principles calculations were conducted on multiple configurations of SrFe12−xXxO19 with x = 0, 0.5 and X = Sm, Gd, Ho. The site preference of each doping element was determined, and the effect of the doping on the structural, electronic, and magnetic properties of the compound was studied. The magnetic properties of this rare earth (Gd, Ho, Sm) doped strontium hexaferrite indicated that this compound could be used in both permanent magnets and water treatment application.

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New nanosized Gd–Ho–Sm doped M-type strontium hexaferrite for water treatment application: experimental and theoretical investigations

Monoclinic α‐NaVOPO4 as cathode materials for sodium‐ions batteries: Experimental and DFT investigation

Elaboration and Experimental Investigation of Zn-Ni-Co Spinel Ferrite Multi-doped Rare-Earth (Gd, Er, and Sm) Prepared by Coprecipitation Method

ZnFe2-x-yGdxSmyO4 (x = y = 0.01) ferrite nanoparticles with average size of 5 nm are synthesized by the co-precipitation method for the first time. X-Ray Diffractometer (XRD) revealed the formation of single-phase spinel with a high crystallinity. Fourier Transform Infrared (FTIR) confirmed the formation of spinel matrix crystallographic sites and Transmission Electron Microscopy (TEM) confirmed the formation of agglomerated spherical particles with nanometric sizes. The analysis of magnetic properties indicates a week ferrimagnetic behavior at low temperatures, while a superparamagnetic behavior is observed at high temperatures. The blocking temperature value is 55 K. A DFT study was performed on the normal, mixed and Sm–Gd co-doped spinel zinc ferrite using the GGA + U method to evaluate their ground state magnetic spin configuration and the effect of Sm3+ and Gd3+ doping on the structural, magnetic and electronic properties of zinc ferrite nanoparticles. It is found that the nanomaterial is most likely to adopt a ferrimagnetic spin arrangement with a degree of inversion close to 0.5. These results suggest that this material has significant function in the industry, which could be beneficial in point of view for telecommunication applications.

M. Elansary

Papers

Magnetic and structural properties of single-phase Gd3+-substituted Co–Mg ferrite nanoparticles

New nanosized Gd–Ho–Sm doped M-type strontium hexaferrite for water treatment application: experimental and theoretical investigations

Monoclinic α‐NaVOPO4 as cathode materials for sodium‐ions batteries: Experimental and DFT investigation

Elaboration and Experimental Investigation of Zn-Ni-Co Spinel Ferrite Multi-doped Rare-Earth (Gd, Er, and Sm) Prepared by Coprecipitation Method

New nanosized (Gd3+, Sm3+) co-doped zinc ferrite: Structural, magnetic and first-principles study