Papers by Keyword: Spinel Ferrites

Abstract: In this study, CuFe₂O₄ nanoparticles with an average crystallite size of approximately 10 nm were produced using the sol-gel autocombustion method. The synthesis was conducted in the presence of polymers with varying monomer counts, aiming to optimize the magnetic properties for possible localized magnetic heating applications. Comprehensive characterization of all samples was conducted using X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FT-IR), and Mössbauer spectroscopy. All synthesized samples exhibited good colloidal stability, with zeta potentials around -18.49mV, +3mV and +24 to +30 mV. The Specific Absorption Rate (SAR) of the synthesized nanoparticles was assessed using the calorimetric method. The SAR values were calculated using both the Initial Slope and the Box-Lucas methods. For the sample synthesized using citric acid, the SAR values were 12.6 W/g and 13.23 W/g, respectively. For samples synthesized using polyethylene glycol, the SAR values ranged from 3 to 7 W/g. The parameters of the alternating magnetic field were 33.3 kA/m and 357 kHz.

Abstract: Nanoscale mixed ferrites with a spinel structure are highly versatile materials widely employed across diverse fields, including engineering, biomedicine, and ecology. This study explores the influence of pH on the structure, morphology, electrophysical, and mechanical properties of CuFe₂O₄ spinel, synthesized using the sol-gel self-combustion method. The investigation reveals that the pH level significantly impacts the structure formation, even at the gel formation stage, thereby shaping the subsequent structure and properties of the synthesized ferrite. X-ray diffraction (XRD) analysis demonstrates that the dominant phase (>90%) corresponds to the cubic spinel phase with the chemical formula CuFe₂O₄, belonging to the Fd3m space group. Notably, the pH of the reaction medium exerts a profound influence on the distribution of iron and copper ions within the octahedral and tetrahedral sublattices of the spinel structure. This variation in cationic distribution manifests in notable changes in the synthesized ferrite's magnetic, mechanical, and degradation properties. Furthermore, the study delves into the impact of the synthesized CuFe₂O₄ spinel as a photocatalyst for degrading organic dyes through the photo-Fenton process. It demonstrates that degradation efficiency is closely related to the ferrite's band gap width and particle size. This study aimed to determine how the pH of the reaction medium impacts the structure, morphology, optical, mechanical, and magnetic characteristics of the nanosized ferrites being synthesized. Furthermore, the synthesized materials were evaluated for their photocatalytic abilities in degrading organic dyes in water. The ferrite powders showcased remarkable dye degradation capabilities via the photo-Fenton process. Degradation efficiency largely hinged on the band gap width and the size of the particles. The most notable outcome was achieved with sample P1, which had particle sizes averaging 12.14 nm. By unraveling the complex relationship between pH, structure, and properties, this research enhances our understanding of the design and optimization of nanoscale mixed ferrites.

Abstract: An urgent task in the field of creating new functional oxide materials is to obtain products with specified properties for specific requirements, which will expand the field of application of such materials in practice. The result of work on this problem will be discussed. The paper presents the results of obtaining and studying the structure and properties of nickel-zinc ferrites doped with cobalt, with the general formula Ni_0.3Zn_0.7-xCo_xFe₂O₄ (with the substitution x equal to 0; 0.1; 0.3; 0.5). The samples were obtained by solid-phase synthesis in a tube furnace with silicon carbide heaters at a temperature of 1150 °C. The porosity of the materials obtained was calculated. For porous ceramic materials, it is one of the quality criteria.

Abstract: In the presented work composite ferroelectric/ferrimagnetic ceramics have been obtained and described. The investigated material is based on PMN-PT powders and Ni-Zn ferrite powder. The Powders of ferroelectric component (i.e. (1–x)PMN-(x)PT with x from 0.25 to 0.40 with step 0.03 were synthesized using the sol-gel method. The magnetic component i.e. nickel-zinc ferrite was obtained from oxides using the classic method of obtaining ceramics. The compositions of PMN–PT used by us have rhombohedral or tetragonal symmetries, or belong to morphotropic region. The final ceramic composite samples were obtained using the classic method of ceramic technology with calcination route and final pressureless densification using free sintering. In this paper, XRD, EDS dielectric and magnetic properties have been investigated and described for the obtained composite ceramic samples.

Abstract: This work describes the technology of growing crystal metamaterials spinel ferrites. Metamaterials is one of the most promising classes of materials for use in optical devices in the microwave range and features, which can be used for creation of controlled attenuators, phase shifters, and other devices.

Abstract: We report the Swift Heavy Ion (SHI) irradiation effect on structural and magnetic properties of Mn_0.5Zn_0.5Fe₂O₄ ferrite nanoparticles. The irradiation experiment has been carried out on three different sized, i.e. 63, 82 and 126 Å, Mn_0.5Zn_0.5Fe₂O₄ particles with 100 MeV Si⁺⁸ ions to a fluence 5 × 10¹³ ions/cm² using the 15UD Tandem accelerator. The XRD measurement reveals that the basic single phase spinel structure remains unaltered after SHI irradiation; however, the lattice parameters and particle size decrease on SHI irradiation. The magnetization measurement carried out at 300 K indicates that all the particles are super-paramagnetic at room temperature, but the applied magnetic field of 70 kOe is insufficient to saturate the system. DC and AC magnetization measurements indicate that on irradiation, the sample with an intermediate size is affected more than the other two.

Abstract: The spinel ferrite system CoZn_zGe_zCr_x-zFe_2-x-zO₄ with z= x^2; x = 0.60, 0.65 and 0.70 was studied by Mà T (ZFC-FC) DC magnetization at low and high fields in the temperature range 5K to 300K, MàH measurements with high field up to 55 kOe at 15K temperature and low field AC susceptibility in temperature range 77K to 300K. We observe thermo-magnetic irreversibility (TMI) in MàT study, high field slope with high coercivity in MàH study. The composition x = 0.70 shows constricted hysterisis loop at 15K. We observed a cusp at transition temperature in AC susceptibility measurements. We have shown that the features observed in all these measurements are adequately explained using domain wall dynamics and inherent magneto-crystalline anisotropy without invoking the concept of cluster spin-glass type ordering in x = 0.60 and x = 0.65 in temperature range 5K to 300K. The sample x= 0.70, however showed signatures of cluster spin-glass type of ordering at low temperature as revealed in non-Brillouin type shape of low field FC curves in MàT DC magnetization and constricted hysterisis loop at 15K temperature.

Abstract: Nanosized particles of AFe₂O₄ compounds (A = Mn, Fe, Co, Ni, Zn) with spinel structure have been synthesized by precipitation from glycol solutions. Diethylene glycol (DEG) was used as high-boiling alcohol medium. Based on NMR studies, the peculiarities of the formation of nanoparticles in glycol solution using metal nitrates as initial reagents have been considered. For the synthesized compounds crystallographic, microscopical and magnetic investigations have been carried out.

Abstract: In the present study magneto-polymer composite coatings are fabricated using nano Zn ferrite, Mn ferrite, Ni ferrite, Zn-Mn ferrite and Zn-Ni ferrite by spraying method. The complex permeabilities, Complex permittivities and microwave absorbing properties within the low frequency of these composites were characterized and investigated. The results showed that the magnetism of the mixed spinel ferrites ( Mn ferrite, Zn-Ni ferrite, Zn-Mn ferrite) are strong but the dielectric properties are weaker, while the magnetism of the normal spinel ferrites (Zn ferrite) is the weakest but provide with a big storage capability of electric energy. The absorbing characteristics of the spinel ferrites are better at 300 kHz-1.5GHz, with minimum absorption of 12.5 dB and the maximum absorption at 480MHz, 1050 MHz and 1400 MHz. The microwave absorbing property of the mixed spinel ferrite Zn-Mn ferrite is best having the RL value being -42.5 dB at 1400GHz.

Abstract: Particle size has significant effect on the magnetic properties of fine particles. In this work, Cu0.2Ni0.8Fe2O4 nano-particles have been synthesized by the co-precipitation method. Different particle sizes were obtained by annealing the samples at various temperatures. The X-ray diffraction (XRD) patterns confirm the formation of cubic spinel structure. The particle size was found to enhance with increasing the annealing temperature. The saturation magnetization and the blocking temperature increase with particle size, which is a typical characteristic of the superparamagnetic behaviour. The dc magnetization measurements show that the samples are superparamagnetic above the blocking temperatures and the blocking temperature of the nanoparticles correlates with the size of the nanoparticles that is found to increase as the function of the particle size. The hysteresis curves show reduction in saturation magnetization in case of nanoparticles as compared to their bulk counterparts. This has been explained on the basis that the magnetic moments in the surface layers of a nanoparticle are in a state of frozen disorder. However, the saturation magnetization increases with particle size, which is a characteristic property of the single domain superparamagnetic particles.