Doped Ferrites Research Articles

Unveiling the structural, optical, electrical, and ferromagnetic properties of Ca2+ doped mixed spinel ferrites for switching field high-frequency device applications

In this paper, the calcium-doped nickel-zinc nano-ferrites [Ni0.5Zn0.5CaxFe2-xO4; x = 0.00, 0.10, and 0.30] were prepared using the chemical co-precipitation synthesis route and studied for switching field high-frequency device applications. The structural analysis has been completed by analyzing X-ray diffraction (XRD) patterns. The Rietveld refined XRD patterns confirmed the formation of cubic spinel structure of Ca2+ substituted nickel-zinc ferrites. The detection of metal-oxygen bonds present at A and B lattice sites has been unveiled by Fourier transform infrared (FTIR) spectroscopy. The morphological studies obtained through FESEM (Field emission scanning electron microscopy) analysis showed a reduction in the particle size from 70 nm to 53 nm when the concentration of Ca2+ ions in Ni-Zn ferrites was increased. Energy dispersive spectra (EDS) confirmed the presence of elements present in the prepared composition. The structure of a cubic spinel-shaped unit cell has been verified from three active prominent Raman modes (A1g, A2g, and T2g). Diffuse-reflectance spectroscopy (DRS) exhibits the increment in the bandgap values (from 1.55 eV to 1.63 eV) which helps fabricate highly efficient photovoltaic devices. The ferroelectric measurements yielded a rise in polarization values from 1.461 μC/cm2 to 18.228 μC/cm2 for 10 % Ca2+ ion substitution. The tangent loss values declined from 24 to 3 in Ni-Zn ferrites upon substituting Ca2+ ions. The Vibrating sample Magnetometer (VSM) technique found the increment in the saturation magnetization (Ms) values from 34.724 emu/g to 54.662 emu/g on substituting up to 30 % Ca2+ ions in Ni-Zn ferrites. These obtained results support the material in switching field distribution for high-frequency applications. The results exhibited that the prepared samples can be applicable for switching devices, filters, and microwave absorption devices. The results revealed the maximum frequency between 12 and 18 GHz which is useful for Ku band absorption.

Scavenger-free solar photocatalytic degradation of Textile Dyes and Antibiotics using magnetically separable bi-junctional photocatalyst

The field of solar photocatalysis has been plagued by photocatalysts with low photon-to-electron conversion efficiency, resulting in poor photocatalytic degradation rates of water pollutants. With a keen idea to improve the existing photocatalysts, we developed a scavenger-free, magnetically separable, bi-junctional solar photocatalyst. The photocatalyst comprises Fe2+ doped zinc ferrite as core, ZnO as shell, and irregular CuO nanoparticles in conjunction with the surface of core-shell nanoparticles prepared using a combination of microwave-assisted solvothermal technique and microwave-assisted reflux method. The photocatalytic degradation properties of the solar photocatalyst were modelled and optimized with the help of Methyl Orange under direct sunlight. This novel composite degrades Methyl Orange roughly four times faster than core-shell nanoparticles. The photocatalyst meets most of the criteria for working of a promising solar photocatalyst, such as 1) excellent absorption of sunlight, 2) two physically distinct heterojunction and absorbing regions for efficient charge carrier generation and separation, 3) scavenger-free degradation of textile dyes and antibiotics, 4) High surface area (39 m2g −1), 5) good stability, 6) excellent reusability, 7) and easy separation of nanoparticles for reuse with the help of a magnet. The prepared photocatalyst efficiently degrades fluoroquinolone antibiotics such as Ciprofloxacin Hydrochloride, Norfloxacin, and Ofloxacin. The photocatalyst demonstrates the capability to efficiently degrade textile dyes such as Methyl Orange, Methylene Blue, Orange G, Fluorescein sodium salt, Rhodamine B, and Crystal Violet. Additionally, the bi-junctional photocatalyst can be coated with a thin layer of silver to achieve twice the degradation rate. This enhancement is attributed to the Localized Surface Plasmon Resonance (LSPR) effect. The current work presents an effective and economical option for removing dyes and antibiotics in wastewater, marking a significant stride towards sustainable industrial practices.

Revolutionizing textile wastewater treatment: Enhanced degradation of dyes using bimetallic Zinc Ferrite-GO nanocomposites

A novel bimetallic nickel-copper doped zinc ferrite based catalyst has been synthesized using the hydrothermal method. The nano-sized bimetallic (Ni-Cu) zinc ferrites were embedded with graphene oxide (GO). The characterization of nano-sized bimetallic (Ni-Cu) zinc ferrites with graphene oxide (GO) involves a comprehensive set of analytical techniques to determine their elemental composition, structural properties, and morphological features. The prepared materials were also subjected to structural and morphological evaluation through FTIR, Raman, XRD, TGA, UV–vis spectroscopy, and SEM with EDX. The experiment for the photodegradation of the selected model pollutant dye, methylene blue was conducted using the prepared materials. This means that the present photocatalyst has a high efficiency of degrading the pollutant to a tune of 99 % within 3 h. When the amount of GO in the prepared nanocomposite was 40 %, there was the perfect result in terms of no degradation of MB. It reduced and deteriorated the degree of band gap energy of the MB dye. The photocatalyst activity was proven to be repeatable; the sample's use was again possible. A decrease in the band gap energy implies that the improved photocatalyst material becomes more efficient at absorbing light energy. This enhanced light absorption promotes the generation of electron-hole pairs, which are essential for catalytic reactions. Therefore, the reduction in band gap energy likely contributes to the catalyst's heightened ability to initiate the degradation of the MB dye, ultimately leading to more effective pollutant removal. In the future, the synthesized sample can be reused without significant loss in its catalytic efficiency, underscoring the stability and durability of the material. The current study has paramount importance for real-world applications; reliable performance over multiple cycles ensures that the catalyst remains effective in addressing pollution challenges over prolonged periods.

Structural elucidation, morphological properties, dielectric properties and their physical interpretation of cerium-substituted cobalt and barium-based M-type hexagonal nano ferrites

This research uses the sol–gel method to look into how adding Co2+ and Ce3+ dopant cations changes the structure, shape, and electrical properties of M-type Ba hexagonal ferrites that have been synthesized. x-ray diffraction (XRD) analysis confirms the successful formation of the targeted hexagonal M-type crystal structure. We observed a reduction in unit cell volume and lattice parameters as the dopant concentration increased, indicating the effective incorporation of dopant ions into the crystal lattice. When the doping process happened, needle-like grain shapes appeared, which could be seen with a field emission scanning electron microscope (FESEM). As the concentration of the dopant increased, the dielectric spectroscopic measurements revealed an increase in the loss tangent (tan δ) from 0.05 to 3.68, and a decrease in the dielectric constant (ε′) from 283 to 3.41. This suggests a reduction in polarization and dielectric permittivity, as well as increased energy dissipation within the material. The electric modulus spectra showed relaxation behaviour that was non-Debye-type, which is another sign that there are complex and multifaceted ways for charges to move. The measurements of relaxation time and AC conductivity showed that the relaxation intervals were not regular and that the conductivity dropped from 2.22*10–4 Ω−1m−1 to 1.4*10–7 Ω−1m−1 as the doping concentration increased. Based on these findings, it seems that the processes of conductivity and dielectric relaxation play a big role in how charges move around in the doped ferrites. We validated complex impedance data obtained through electrochemical impedance spectroscopy (EIS) software against calculated impedance values. The derived grain and grain boundary characteristics also agreed with the observed grain distribution and boundaries from the micrographs, further corroborating the analysis.

Correction: Structural, cation distribution, mechanical, and optical properties of rare-earth doped cadmium zinc ferrites

Correction: Structural, cation distribution, mechanical, and optical properties of rare-earth doped cadmium zinc ferrites

High photocatalytic degradation of methylene blue and enhancing the magnetization, AC conductivity of Dy3+ and Ce3+ doped CdCoFe2O4 nano ferrites

Photocatalysts that combine with dielectric and magnetic properties are vital because of a wide variety of applications for these combinations, and nanostructured magnetic semiconductive materials have attracted significant interest due to their potential applications. A series of Cd0.4Co0.6DyXCeXFe2-2XO4 spinel nano ferrites (nFs) were synthesized by using a highly efficient low-temperature method of citrate sol-gel auto-combustion for Methylene Blue (MB) dye degradation photocatalysts under visible light irradiation that combines with dielectric and magnetic properties are vital because of a wide variety of applications for these combinations, and nanostructured magnetic semiconductive materials have attracted significant interest due to their potential applications. The recycled MB is one of the hazardous textile dyes that is used extensively but causes risks for both humans and the environment. The prepared Dy3+ and Ce3+ doped Cd–Co nFs were polycrystalline with cubic structure, and crystalline size was increased from 15.78 to 21.02 nm with higher crystallinity, and the surface morphology changes from a spherical shape to a hexagonal shape with higher doping concentrations. The direct optical band gap values are increased. FTIR spectra reveal the stretching vibrations along the [M↔O] bond tetrahedral (A) and octahedral (B) sites. HRTEM results revealed that the prepared Cd–Co nFs have higher crystalline nature and high porosity. VSM indicates the sample's soft magnetic action and hysteresis loops showed the highest saturation magnetization (Ms) is 12.243 emu/g, and retentivity increases around 6.038 emu/g, decreasing the dielectric tangent loss, dielectric constant and dielectric loss. The AC conductivity raised with applied frequency. The PL gives a blue emission, and photocatalytic has the highest degradation activity 40.93 % of MB would be successful after 120 min irradiation of X = 0.07 Dy3+ and Ce3+ doped Cd–Co nFs.

Gd-doped ZnFe2O4 multi-shell microspheres for enhancing photocatalytic H2 production or antibiotic degradation

It is anticipated to remove highly hazardous tetracycline antibiotic from aqueous solution photocatalytically by using Gd doped spinal ferrite. In this work, both ZnFe2O4 and Gd doped ZnFe2O4 photocatalysts were hydrothermally fabricated and characterized by different techniques. The spherical photocatalysts show extended photocatalytic removal efficiency under visible light. The optimized sample (ZnFe1.96Cd0.04O4) removes 78% antibiotic in 80 min. Moreover, under simulated solar light irradiation, the rate of hydrogen produced from water splitting photocatalysis with ZnFe1.96Cd0.04O4 reaches 230.4 μmol/(g·h). These increased activities are attributed to the increased specific surface area, the expanded light absorption range and the enhanced charge separation realized by doping Gd. According to the charge trapping study, both superoxide (•O2−) and hydroxyl radicals (•OH) were the major active species in the process of removing antibiotic. This research provides a feasible way to fabricate low cost photocatalysts for the eradication of highly hazardous pollutants from aqueous solution.

Structural, cation distribution, mechanical, and optical properties of rare-earth doped cadmium zinc ferrites

Structural, cation distribution, mechanical, and optical properties of rare-earth doped cadmium zinc ferrites

Enhancing layered perovskite ferrites with ultra-high-density nanoparticles via cobalt doping for ceramic fuel cell anode

Nanoparticles anchored on the perovskite surface have gained considerable attention for their wide-ranging applications in heterogeneous catalysis and energy conversion due to their robust and integrated structural configuration. Herein, we employ controlled Co doping to effectively enhance the nanoparticle exsolution process in layered perovskite ferrites materials. CoFe alloy nanoparticles with ultra-high-density are exsolved on the (PrBa)0.95(Fe0.8Co0.1Nb0.1)2O5+δ (PBFCN0.1) surface under reducing atmosphere, providing significant amounts of reaction sites and good durability for hydrocarbon catalysis. Under a reducing atmosphere, cobalt facilitates the reduction of iron cations within PBFCN0.1, leading to the formation of CoFe alloy nanoparticles. This formation is accompanied by a cation exchange process, wherein, with the increase in temperature, partial cobalt ions are substituted by iron. Meanwhile, Co doping significantly enhance the electrical conductivity due to the stronger covalency of the CoO bond compared with FeO bond. A single cell with the configuration of PBFCN0.1-Sm0.2Ce0.8O1.9 (SDC)|SDC|Ba0.5Sr0.5Co0.8Fe0.2O3−δ (BSCF)-SDC achieves an extremely low polarization resistance of 0.0163 Ω cm2 and a high peak power density of 740 mW cm−2 at 800 °C. The cell also shows stable operation for 120 h in H2 with a constant current density of 285 mA cm−2. Furthermore, employing wet C2H6 as fuel, the cell demonstrates remarkable performance, achieving peak power densities of 455 mW cm−2 at 800 °C and 320 mW cm−2 at 750 °C, marking improvements of 36% and 70% over the cell with (PrBa)0.95(Fe0.9Nb0.1)2O5+δ (PBFN)-SDC at these respective temperatures. This discovery emphasizes how temperature influences alloy nanoparticles exsolution within doped layered perovskite ferrites materials, paving the way for the development of high-performance ceramic fuel cell anodes.

Effect of Pr substitution on structural, electrical and magnetic properties of NiZnCo ferrite for high frequency applications

With the miniaturization, chip, and integration of electronic products, the working frequency of electronic components is also getting higher and higher, which puts forward requirements for us to seek high-frequency materials with higher performance. To enhance NiZnCo ferrite properties, this study introduced the rare earth element Pr for modification and thoroughly examined its impact. The material Ni0.55Zn0.3Co0.15PrxFe2-xO4 (NZCPF, 0 ≤ x ≤ 0.1) was synthesized by sol-gel self-propagating technique. The X-ray diffraction of NZCPF indicates that Pr3+ doped NiZnCo ferrites still keep the cubic spinel structure. With the increasing substitution of Pr3+ ions in NiZnCo ferrite, the average grain size of the sample decreases from 1.05 μm to 0.73 μm. After the addition of Pr3+ ions, the dielectric loss takes its minimum value (0.41@100 Hz), and the DC resistivity ρ takes its maximum value (4×106 Ω·m@30℃). The value of μ' (@10 MHz) monotonically decreases from 11.9 to 5.9 as the doping amount of Pr3+ ions, denoted by x, increases. The saturation magnetization intensity decreases from 68.05 to 58.45 emu/g, and maximum magnetic loss decreases about 30% (0.65@1 GHz). It is worth noting that the resonance frequency fr increases from 343 MHz to 638 MHz with x increases, which is a substantial improvement compared to previous studies. Generally, the introduction of Pr3+ ions into NiZnCo ferrite results in outstanding electromagnetic characteristics, offering a valuable reference to the advancement of compact and high-frequency devices.

Effect of Cr and Ni on mechanical response and microstructural evolution of nanocrystalline ferrite: A molecular dynamics study

Microalloying plays a critical role in improving the mechanical properties of steel. To offer a better theoretical guide for experimental research at the atomic level, this paper investigated the synergistic mechanism of adding trace amounts of alloy Cr and Ni and the microstructure evolution of nanocrystalline ferrite during the mechanical response process. First-principles calculations were implemented to investigate electronic properties. Hybrid molecular dynamics and Monte Carlo simulations were employed to explore the deformation mechanism under uniaxial tension and scratching. Specifically, comprehensive differences between doped and pure nanocrystalline ferrites were explored regarding local stress-strain state, dislocation evolution, twin expansion, and grain boundary activity. The results show that Cr- and Ni-doped nanocrystalline ferrite has higher strength and better wear resistance. The potential mechanism is that the addition of Cr and Ni enhances the atomic bonding strength with Fe atoms, hinders the movement of dislocations caused by lattice distortion, and suppresses grain boundary slip and migration, thereby improving the resistance to plastic deformation and grain boundary stability. Theoretical calculations based on microstructure indicate that compared to solid solution strengthening, Ni-induced grain boundary strengthening plays a dominant role in improving yield strength. Under large deformation, the trend of mechanical response is reversed. The suppression of dislocation motion by Cr reduces the dislocation density and dislocation entanglement, resulting in flow stress and local scratch force being smaller than that of pure samples. However, the formation of more nanoscale twins and twin-dislocation interactions enhances strain-hardening ability during tensile. Finer nanostructured subgrains are formed under scratching. These results provide valuable insights into the understanding of the strengthening mechanism and plastic deformation mechanism of Cr-Ni system low alloy steel under dynamic loading.

Multi-characterization and antipathogenic bacterial activities of cerium doped manganese nano ferrites: Structural, and magnetic insights

Due to the uniqueness and the variation of the ionic radius and oxidation states of the implanted transition metals within nano ferrites structure, The nano ferrites are integrated into many technologies including biomedical application the current study aims to optimize the effect of cerium-dopant on the magnetic behavior and antimicrobial properties of manganese nano ferrites. Cerium-doped manganese nano ferrites are synthesized by chemical co-precipitation method followed by thermal annealing at 500 °C. and investigate the dopant effects on its magnetic behavior and antibacterial properties for biomedical applications. The cubic spinel ferrite is successfully formed and CeO2 and Fe2O3 have appeared as minor phases. The particle size is found to be 20–60 nm. The Ce0.05Mn0.95Fe2O4 nano ferrite exhibits the highest saturation magnetization of about 20.47 emu/g with 118.22 Oe as coercivity. EPR factors were affected due to crystalline anisotropy that appeared inside the CexMnX-1Fe2O4 spinel ferrites nanomaterials. In comparison to chloramphenicol, cerium nanoparticles exhibited promising inhibitory action against six pathogenic bacteria (Bacillus cereus, Bacillus subtilis, Micrococcus luteus, Escherichia coli, Klebsiella pneumoniae, and Serratia plymuthica). All cerium treatments showed suitable antibacterial activities. However, the treatments of X = 0.000, X = 0.025, and X = 0.050 were the most effective. For Gram-negative bacteria, the best treatment was X = 0.025, while for Gram-positive isolates, the best treatment was X = 0.050 with MIC 5–10 µg/ml. Our finding, open the pathway to integrate cerium doped manganese nano ferrites in biomedical application including against human pathogenic bacteria.

Effect of Bi2O3-CuO Flux on the Microstructure, Soft Magnetic Properties, and Gyromagnetic Properties of NiCuZn Ferrites for LTCC Devices.

In this work, the electromagnetic properties of Ni0.22Cu0.31Zn0.47Fe2O4 (NiCuZn) ferrites doped with 0.3 wt% Bi2O3 + xCuO flux (x = 0.2, 0.4, 0.6, and 0.8 wt%) were studied. Doping resulted in a reduction in the sintering temperature to 900 °C. The doped ferrites were synthesized via the solid-state method. XRD patterns revealed that the prepared ferrites had a cubic spinel structure; thus, a moderate addition of flux did not change the crystal structure. The SEM images, as well as the density and grain size distribution of the samples, showed that the NiCuZn ferrites had densified, homogenized, and contained fully grown grains for x = 0.6 wt%. The sample exhibited good soft magnetic properties, with μ' reaching the maximum value of 245.4 for x = 0.6 wt% and ε', Ms, and Hc reaching the maximum values of 23.1, 28.06 emu/g, and 45.86 Oe for x = 0.8 wt%, respectively. Furthermore, the ferrites exhibited good gyromagnetic properties, with 4πMs reaching the maximum value of 1744 Gauss for x = 0.8 wt% and ΔH reaching the minimum value of 228 Oe for x = 0.6 wt%. NiCuZn ferrites were successfully sintered at a lower temperature (900 °C) by adding Bi2O3-CuO flux through LTCC technology and exhibited good soft magnetic properties and gyromagnetic properties. We envisage that these ferrites could be used in multilayer devices.

Preparation and characterization of various PVPylated divalent metal-doped ferrite nanoparticles for magnetic hyperthermia.

There is an incessant demand to keep improving on the heating responses of polymeric magnetic nanoparticles (MNPs) under magnetic excitation, particularly in the pursuit for them to be utilized for clinical hyperthermia applications. Herein, we report the fabrication of a panel of PVP-capped divalent metal-doped MFe2O4 (M ≅ Co, Ni, Zn, Mg, and Sn) MNPs prepared via the Ko-precipitation Hydrolytic Basic (KHB) methodology and assess their magneto-thermal abilities. The physiochemical, structural, morphological, compositional, and magnetic properties of the doped ferrites were fully characterized using various techniques mainly TEM, XRD, EDX, FTIR, and VSM. The obtained doped MNPs exhibited stabilized quasi-spherical sized particles (10-17 nm), pure well-crystallized cubic spinel phases, and high saturation magnetizations (Ms = 26-81 emu g-1). In response to a clinically-safe alternating magnetic field (AMF) (f = 332.8 kHz and H = 170 Oe), distinctive heating responses of these doped ferrites were attained. Hyperthermia temperatures of 42 °C can be reached very fast in only ∼5 min, with heating temperatures slowly increasing to reach up to 55 °C. The highest heating performance was observed for PVP-NiFe2O4 and the lowest for PVP-Sn-doped NPs (SAR values: PVP-NiFe2O4 > PVP-CoFe2O4 > PVP-ZnFe2O4 > PVP-MgFe2O4 > PVP-SnFe2O4). This trend was found to be directly correlated to their observed magnetic saturation and anisotropy. Heating efficiencies and specific SAR values as functions of concentration, frequency, and amplitude were also systematically investigated. Finally, cytotoxicity assay was conducted on aqueous dispersions of the doped ferrite NPs, proving their biocompatibility and safety profiles. The PVPylated metal-doped ferrite NPs prepared here, particularly Ni- and Co-doped ferrites, are promising vehicles for potential combined magnetically-triggered biomedical hyperthermia applications.

Rare Earth Metal Samarium Doped Ferrite and Its Structural, Morphological, Magnetic, and Optical Studies for Biomedical Applications

The x-ray diffraction analysis manifested the single phases of Fe2O3, SmFeO3, and v SmFeO3 synthesized via sol-gel route. The Fe2O3, SmFeO3, and v SmFeO3 were hexagonal, orthorhombic, and cubic, respectively. The Debye-Scherer formula was used to calculate the average crystallite size of Fe2O3 (85.54 nm), SmFeO3 (67.65 nm), and v SmFeO3 (49.58 nm). The FESEM reveals near-spherical morphology with average particle sizes of 173, 114, and 161 nm, respectively. VSM analysis revealed the enhanced magnetic behavior of SmFeO3 and v SmFeO3 compared to Fe2O3. Antimicrobial activity against both E. coli and S. aureus bacteria justifies the biomedical application.

Defect-Engineering by Solvent Mediated Mild Oxidation as a Tool to Induce Exchange Bias in Metal Doped Ferrites.

The crystal site occupancy of different divalent ions and the induction of lattice defects represent an additional tool for modifying the intrinsic magnetic properties of spinel ferrites nanoparticles. Here, the relevance of the lattice defects is demonstrated in the appearance of exchange-bias and in the improvement of the magnetic properties of doped ferrites of 20nm, obtained from the mild oxidation of core@shell (wüstite@ferrite) nanoparticles. Three types of nanoparticles (Fe0.95 O@Fe3 O4 , Co0.3 Fe0.7 O@Co0.8 Fe2.2 O4 and Ni0.17 Co0.21 Fe0.62 O@Ni0.4 Co0.3 Fe2.3 O4 ) are oxidized. As a result, the core@shell morphology is removed and transformed in a spinel-like nanoparticle, through a topotactic transformation. This study shows that most of the induced defects in these nanoparticles and their magnetic properties are driven by the inability of the Co(II) ions at the octahedral sites to migrate to tetrahedral sites, at the chosen mild oxidation temperature. In addition, the appearance of crystal defects and antiphase boundaries improves the magnetic properties of the starting compounds and leads to the appearance of exchange bias at room temperature. These results highlight the validity of the proposed method to impose novel magnetic characteristics in the technologically relevant class of nanomaterials such as spinel ferrites, expanding their potential exploitation in several application fields.

Development and synergistic effects of magnetodielectric Dy-Gd co-doped YIG nanoferrites based meta-absorber for improved absorption applications

Microwave materials with outstanding absorbing power and low cost are decisive for the electromagnetic issues in stealth technology. In the present work, Dy-Gd substituted YIG nano ferrites having Y3−x-yDyx GdyFe5O12; (whereas x = 0.00, 0.025, 0.05, 0.075, 0.10; y = 0.00, 0.25, 0.50, 0.75, 1.00), were prepared by two-step sol-gel self-ignition route for absorption purpose. Rare earth cations such as Dy-Gd effects on the structural, and electromagnetic characteristics of YIG were evaluated. Different characterizations like XRD, FESEM, and VSM were used to evaluate the physicochemical and electromagnetic properties of the Dy-Gd co-doped YIG ferrites. A high-frequency vector network analyzer evaluated dielectric measurements such as real and imaginary permittivity and permeability, ac-conductivity, and dielectric loss of the Dy-Gd doped YIG ferrites. Dy-Gd doped YIG ferrites samples depicted single phase cubic garnet structure. Cation distributions of Dy-Gd doped YIG ferrites were also calculated. FESEM images revealed a homogeneous, closely packed grain size distribution of the Dy-Gd doped YIG samples. Magnetic properties such as saturation magnetization, remanence, coercivity, initial permeability, magnetic anisotropy constant, and Bohr magneton were also investigated using magnetic hysteresis loops and the SFD and high-frequency evaluations. Dielectric properties such as dielectric losses, ac conductivity, permeability, and permittivity of the Dy-Gd doped YIG samples show high values at x = 0.075 and y = 0.75. Metamaterial-based Dy-Gd doped YIG absorbers were designed and simulated in the CST software. The resonance peaks depicted the absorption at 3.6 GHz with absorptivity of 67 %, 75 %, and 85 % for x = 0.00- y = 0.00, x = 0.05-y = 0.5, and x = 0.075-y = 0.75, respectively. High saturation magnetization, low coercivity, and extraordinary dielectric absorption characteristics of Dy-Gd doped YIG ferrites make them appropriate for absorption, and EMI shielding applications in microwave regime.

Dipolar and anisotropy effect on dextran coated Cu doped ferrite for magnetic hyperthermia applications

The dipolar interaction and magnetic anisotropy effect are the key parameters to tune the self-heating effect of magnetic nanoparticles (MNPs). In this paper, we investigate the impact of Cu2+ doped Fe3O4 and dextran coated nanoparticles (CuxFe3-xO4 with x = 0.15, 0.31, and 0.47) on thermal properties using specific absorption rate measurements (SAR). We look into the prospect of using dipolar and anisotropy effects to increase or decrease the heat released by magnetic nanoparticles, potentially boosting hyperthermia applications. Magnetic nanoparticles with an average particle size of 12–20 nm were observed via TEM. The influence of Cu2+ doping on the structural and magnetic properties of the samples was studied using a vibrating sample magnetometer (VSM). The effective anisotropy calculated for x = 0.15 and x = 0.47 were 5.5 and 4.4 j/m3 respectively. It was shown that increasing the copper doping reduced the effective anisotropy, lowering the SAR values. The SAR value obtained for x = 0.15 and dex-x = 0.15 were 787 and 591 W/g respectively. The uncoated CuxFe3-xO4 nanoparticles achieved hyperthermia temperatures (42–48 °C) much faster than the dextran-coated samples. Eventually temperature can be adjusted to the desired hyperthermia temperature range by altering the sample and Cu2+ concentration. The dextran coating has been shown to dramatically reduce SAR values while still assisting in magnetic hyperthermia temperature regulation. The study also demonstrated that the dipolar interaction influenced the Néel relaxation mechanism which was important in the heat generation mechanism of the MNPs

Zn and Ni doping effect on barium hexaferrite ferroelectric, optical properties and photocatalytic activity under visible light irradiation

In this study, we explored the potential photocatalytic activity of doped ferrites by examining the effects of zinc and nickel doping on barium hexaferrite (Ba1-xZnxFe12-yNiyO19) nanoparticles. To prepare the samples, we utilized a micro-emulsion approach and evaluated the influence of dopants on their structural, ferroelectric, and photocatalytic properties. The X-ray diffraction and Raman spectra indicated that the synthesized samples were hexagonal and belonged to the P63/mmc space group. The average crystallite size has been calculated in the range of 64–67 nm. By enhancing the dopant concentration, the optical bandgap decreased from 2.19 (eV) to 1.48 (eV). The material with a narrow bandgap is useful for catalytic application and PL signal was also revealed low-rate recombination of e−-h+ pair. Moreover, photo-degradation experiment was carried out by degrading the methyl violet dye under visible light irradiation. The highly substituted material furnished 87% of dye removal, which was 56% in case of undoped sample. The Ba1-xZnxFe12-yNiyO19 material demonstrates great potential as a photocatalyst for the degradation of dyes in effluents when exposed to visible light. This finding suggests that this material could be a valuable solution for addressing the challenges posed by dye contamination in wastewater.

Ni–Ag ferrites synthesized by sol gel route using aloe vera extract as a solvent: Enhancement in structural, dielectric, magnetic and optical properties

The Ag+ doped nanocrystalline nickel ferrites, NiAgxFe2-xO4 (NAF) with x = 0–0.1 were synthesized by sol gel route using aloe vera extract as a solvent. The analysis of X-ray diffractogram reveals the creation of spinel phase within the pristine Ni ferrite. The phase of nano Ag particles coexists along with the spinel phase for doped NAF, which was confirmed by the Rietveld refinement of XRD patterns. The wt. % of metallic nano Ag and spinel phase was calculated from the refined XRD data. The mean size of the ferrite crystallites calculated from Debye-Scherer method was 44 nm. The TEM analysis confirms the nanocrystalline nature of the ferrites. The SAED image of the ferrite confirms the creation of spinel phase within the ferrite. The morphological analysis by SEM explores the layered arrangement of spherical nanoparticles within the NAF crystals. The EDS analysis shows the absence of impurity elements in the synthesized ferrites. The dielectric constant and loss tangent were studied as a function of frequency and Ag+ composition. The analysis of hysteresis loops depicts the soft magnetic behavior of the NAF samples. The optical properties of NAF crystals were studied from the UV Vis absorption spectra within the wavelength range 400–800 nm. The band gap energies were decreased with the increasing Ag+ composition due to the contribution of delocalized electrons in direct optical transitions.