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La3+, Sm3+, Nd3+, and Gd3+substituted Co–Ni system (Co0.5Ni0.5Fe2–xRExO4; where RE3+ = La3+, Sm3+, Nd3+, and Gd3+; x = 0.0 and 0.06) ferrite materials have been synthesized using the solid-state reaction method. XRD, SEM, FTIR, DC electrical resistivity and VSM studies were carried out on these synthesized materials. It is found that RE3+ ions have substituted Fe3+ ions in the B sites. The X-ray powder diffraction pattern shows the formation of a spinel structure. No extra peak of rare earth ions was observed in the XRD pattern, possibly due to the small amount of doping of rare earth ions. The lattice parameter of the substituted ferrites is observed to increase as the ionic sizes of the RE ions increase, although fluctuations are sometimes observed. The samples are agglomerated and almost spherical, according to SEM analysis. The FTIR absorption bands represent the predicted range of spinel ferrites. D.C. electrical resistivity and saturation magnetization increase with the increase in substituted RE3+ ions. [ABSTRACT FROM AUTHOR]

The series of Cr-substituted Co–Cu nanoferrite materials have been developed having the chemical compositions Co0.7Cu0.3Fe2-xCrxO4, x = 0.00, 0.05, 0.10, 0.15, 0.20, and 0.25. These ferrite materials are prepared by using the solgel auto combustion method. These materials are characterized by XRD, FESEM with EDS, HRTEM, FTIR, dc resistivity, and VSM studies. Chromium is found to occupy the B-sites replacing Fe3+ ions. The density of all the materials is found to increase except at higher values of Cr concentration. The lattice parameter of Cr-substituted ferrites is found to increase with the rise of Cr content. The dc resistivity is decreasing with an increase in temperature and thus reveals the materials' semiconductor nature. VSM study was utilized to characterize and estimate the magnetic features like magnetic saturation and the samples' coercivity. [ABSTRACT FROM AUTHOR]

[Display omitted] • In this case, co-doping Mg2+ and Ce3+ into CoFe 2 O 4 was done to examine the parent material's structural, electrical, and magnetic properties. • The Powder XRD phase analysis showed a single phase with space group Fd -3 m during phase formation. • The FESEM has been used to study the morphological natures, and the images show a reduced grain size with two dopants content. • In order to confirm the production of the pure phase FTIR spectroscopy was used. This technique revealed the characteristic spinel ferrite absorption bands in the 600–417 cm−1 frequency range. • DC electrical resistivities were examined the materials with high resistivity could still be created at high temperatures. • The substitution by a lower magnetic substance has decreased the saturation magnetization of the resultant ferrite which is clearly shown from the VSM result. Mg2+ and Ce3+ doped Cobalt ferrites Co 1-x Mg x Fe 2-y Ce y O 4 (x = 0.0, 0.25, 0.5 and 0.75; y = 0.0, 0.03, 0.06, and 0.09) were synthesized chemically through the sol–gel auto combustion method. The structural analysis was done using X-ray diffraction (XRD) analysis, Field Emission Scanning Electron Microscopy (FESEM), and Fourier Transform Infrared Spectroscopy (FTIR) analysis. XRD study showed the ferrite's formation of spinel cubic structure. The outcomes of FESEM images show that the particles are homogenous with minor agglomeration. The formation of peak ϑ 1 around 600 cm−1 and ϑ 2 around 400 cm−1 is shown by FTIR, confirming the formation of the spinel structure. High dopant concentrations result in increased DC electrical resistance. High-resistance materials with a decreased dielectric constant and loss are obtained by substituting Mg2+ and Ce3+ cations at the Co2+ and Fe3+ sites. These materials are suited for high-frequency devices. Additionally, it was observed that the AC conductivity was dispersed across the applied frequency ranges and exhibited a lower value than the parent material. The effect of the substituted on magnetic studies was examined systematically using a VSM at a temperature in the room. The magnetization measurements show that the synthesized contents increases, magnetization values decrease, and coercivity increases. [ABSTRACT FROM AUTHOR]

• Cu 0.7 Co 0.3 Fe 2−x Cr x O 4 ferrite nanoparticles were synthesized by sol-gel auto-combustion technique. • XRD, FESEM-EDS, TEM, FT-IR spectroscopy, dc electrical resistivity, and VSM studies were conducted. • Substitution of Fe3+ by Cr3+ in Cu 0.7 Co 0.3 Fe 2−x Cr x O 4 affects the Coercivity and saturation magnetization. • Cu 0.7 Co 0.3 Fe 1.95 Cr 0.05 O 4 delivered the lowest saturation magnetization (25.23 emu/g). • Non-monotonic variation of the structural and magnetic parameters have been recorded. Using sol-gel auto combustion technique complex ferrite nanoparticles have been synthesized. Characterization with the help of X-ray diffraction (XRD) revealed that the synthesized materials Cu 0.7 Co 0.3 Fe 2−x Cr x O 4 are of a single-phase cubic spinel structure with Fd-3 m space group. And also, the samples' crystallite sizes calculated using XRD data yielded in the range of 19.28–32.92 nm. The lattice constants are calculated to be between 8.4099 Å and 8.4441 Å. The FTIR results revealed that the spinel structure remained undisturbed even after the Cr ions were doped. FESEM images display the materials constitute polygonal-shaped grains though at times irregularly shaped gains with slight agglomeration appear. EDS analysis confirmed that the sample contained the constituent elements. A decreasing pattern in DC resistivity with an increase in temperature was observed, ensuring the semiconducting character of the ferrites under investigation. VSM was utilized to characterize and estimate the magnetic features like magnetic saturation and coercivity of the samples. [ABSTRACT FROM AUTHOR]

[Display omitted] • The single phase CoFe 2-x Ce x O 4 (x = 0.0, 0.04, 0.08, and 0.12) was synthesised using the sol–gel auto-combustion method with citric acid fuel. • XRD data confirms the presence of the cubic spinel structure of the ferrite nanoparticles. • The FESEM findings show that the particles are homogenous, uniformly dispersed, and slightly aggregated. • The FTIR spectrum shows a strong ferrite microstructure and the main effects of the chemical combination. • It has been found that the magnetic properties decrease as Ce3+ concentrations increase. The sol-gel auto-combustion method produced rare earth Ce3+ substituted Cobalt ferrite nanomaterials, CoFe 2-x Ce x O 4 (x = 0.0, 0.04, 0.08, and 0.12). An X-ray diffractometer, a Field effect scanning electron microscope, a Fourier transform infrared spectrometer, a DC electrical resistivity, and a vibrating sample magnetometer were used to investigate them. The structural, dc resistivity and magnetic properties were examined using standard techniques. XRD analysis revealed a cubic spinel structure in a single phase without any impurity phase for all the prepared samples. With increasing Ce3+ content, a decrease in crystallite size was observed according to Scherrer's formula. Grain size and surface morphology determined from FESEM analysis were 20 to 30 nm. The samples' cubic spinel ferrite properties may be seen in the FTIR data, which show two distinct absorption bands related to the octahedral site at 400 cm−1 and the tetrahedral site at 600 cm−1. FTIR also confirms the presence of Ce3+ in the crystal structure. As the Ce3+ content increases, the DC resistivity decreases, confirming the material's semiconducting nature and temperature increase in all the synthesized samples. The magnetic behaviour strongly influences the substitution of Ce3+ ions. The samples' paramagnetic properties are enhanced by saturation magnetization. The size of the particles affects their coercivity. For the use of nano cobalt ferrite particles in high-density recording media, the M S and H C can be modified. [ABSTRACT FROM AUTHOR]