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This paper studies a novel surface plasmon resonance (SPR) biosensor using a BK7 glass prism, a copper (Cu) metal plasmonic layer, which combine a halide perovskite (FASnI3) with two-dimensional (2D) materials such as phosphorus black, graphene and TMDC (MoS2, MoSe2, WS2, WSe2) for the detection of breast cancer cells. We have optimized the thickness of each layer in order to obtain maximum sensitivity. A numerical study mainly uses the transfer matrix principle, while the attenuation total reflection method involves examining the reflection properties. The evaluation of SPR biosensor configurations serves to obtain optimal performance. The simulation results indicate that the integration of halide perovskite (FASnI3) and 2D materials into the BK7/Cu/medium sensing structure significantly improves the sensitivity and figure of merit (ZT). The outstanding results in terms of sensor performance characteristics are observed in the BK7/Cu (48 nm)/FASnI3 (5 nm)/BP (0.53 nm) configuration. The figure of merit and sensitivity estimated at 123.11 RIU−1 and 459.28°/RIU, with a notable improvement of 338.45 %.

The development of the functional magnetic composites with determined properties is important task for modern material sciences. Control of magnetic and electrodynamic properties realized by the ceramic/polymer composites preparation. Conduction of the investigations of the correlation between chemical composition of the fillers (magnetic powders) and their concentration in the polymer matrix is the best way for solving this task. Two- and tree-component spinel-polymer composites were produced by thermal pressing. As spinels, CoFe2O4 (CF) and Ni0.4Cu0.2Zn0.4Fe2O4 (NCZFO) were used. As a polymer, FEP was used. The concentration of the spinels in the polymer matrix was fixed at 20 mass.%. Investigation of the structural features and magnetic properties were carried out. The impact of the chemical composition and phase ratio of the composites on crystal structure, microstructure, and magnetic properties were established. Magnetic measurements were performed at 300 and 10 K in the fields up to 70 kOe. It was demonstrated that the synergetic effect of ceramic composites violates of the principle of additivity in two-phase ceramic composites. The impact of the polymer matrix on magnetic properties was demonstrated. It opens new perspectives for practical applications of such kind of materials.

In the pursuit of sustainable porcelain production, this research examines the potential of using recovered automotive glass as a substitute for traditional feldspar, specifically feldspar imported from Spain. Porcelain samples were sintered at different temperatures and with varied proportions of automotive glass. The crystalline phases formed post-sintering were determined through X-ray diffraction and quantified by dissolving the porcelain in concentrated hydrofluoric acid. Results revealed that the inclusion of automotive glass, owing to its dissolved oxide content, accelerated the porcelain melting process and led to an increase in the vitreous phase. Notably, anorthite phases became dominant and mullite formation was evident at 1100 °C, stabilizing in samples G00 and G10, and then increasing at 1200 °C due to the emergence of secondary mullite. This secondary mullite forms from the residual silica after the primary mullite formation and the aluminium in the feldspars, which is about 17 %. For samples G20 and G30, only primary mullite was observed due to the decreased aluminium content resultant from feldspar replacement by glass. These findings underscore the viability of automotive glass in porcelain production, providing a sustainable and effective alternative to feldspar.

Abstract Improving efficient electrocatalysts (ECs) for hydrogen generation through water splitting is of significant interest in tackling the upcoming energy crisis. Sustainable hydrogen generation is the primary prerequisite to realizing the future hydrogen economy. This work examines the electrocatalytic activity of hydrothermally prepared vanadium doped MnCo spinel oxide microspheres (MC), MnVxCo2−xO4 (Vx-MnCo MC, where x ≤ 0.4) in the HER (hydrogen evolution reaction) process. Magnetization measurements demonstrated a paramagnetic (at high temperatures) to a ferrimagnetic (at low temperatures) transition below the Curie temperature (Tc) in all the samples. The magnetization is found to intensify with the rising vanadium content of MCs. The optimized catalyst Vx-MnCo MCs (x = 0.3) outperformed other prepared ECs with a Tafel slope of 84 mV/dec, a low onset potential of 78.9 mV, and a low overpotential of 85.9 mV at a current density of 10 mA/cm2, respectively. The significantly improved HER performance of hydrothermally synthesized Vx-MnCo MCs (x = 0.3) is principally attributable to many exposed active sites, accelerated electron transport at the EC/electrolyte interface, and remarkable electron spectroscopy for chemical analysis (ECSA) value was found ~ 11.4 cm2. Moreover, the Vx-MnCo MCs (x = 0.3) electrode exhibited outstanding electrocatalytic stability after exposure to 1000 cyclic voltametric cycles and 36 h of chronoamperometric testing. Our results suggest a feasible route for developing earth-abundant transition metal oxide-based EC as a superior electrode for future water electrolysis applications.

Melt quenching technique was used to prepare (30-x)Li2O–xNa2O–40B2O3–30GeO2 glasses (x = 0, 5, 10, 20 & 30 mol %). The room temperature infrared spectra of the powdered glass samples were recorded in the range of 400–2000cm−1. Raman measurements were performed in the range of 200–2000cm−1 at room temperature. Raman and Infrared spectroscopy was utilized for structural study of this glass system. Specific modes of vibration and peak position were identified from de-convolution of infrared and Raman spectra using Gaussian fitting. Ge–O–Ge bonds’ symmetrical stretching vibrations related to 3 members GeO4 rings were allotted to the IR band of 483 cm−1. The strongest Raman band was allotted to symmetrical stretching vibrations of Ge–O in GeO4 having one non-bridging oxygen with 3 bridging oxygens at 797 cm−1. The observed Raman and IR spectra of various specimens are utilized here to explain the structural characteristics of current glass.

Magnetic and optical properties of copper doped spinel calcium ferrite (Ca1-xCuxFe2O4; x = 0, 0.2, 0.4, 0.6, 0.8, 1) nanoparticles (NPs) have fascinated the attention of researchers. Spinel Ca1-xCuxFe2O4 NPs were prepared by co-precipiation technique. The as prepared compositions were subjected to structural, magnetic, electrical and optical properties. Cubic spinel phase was observed through powder X-ray diffraction (PXRD) studies and the lattice constant increased with increase in calcium concentration and the average crystallite size in the range 32–19 nm. Transmission Electron microscope (TEM) technique provided information on the morphology of the synthesized ferrites. FT-IR spectral bands observed at 579, 480 and 514 cm−1 confirmed the M−O vibration for Ca–O, Fe–O and Cu–O bands responsible for the formation of spinel. Magnetization, coercivity and retentivity were calculated from vibrating sample magnetometer (VSM) studies. Hysteresis loops revealed the magnetic behavior of the prepared Ca1-xCuxFe2O4 NPs. The adsorption and desorption measurement were achieved from Brunauer–Emmett–Teller (BET) analysis. Band gap of the prepared spinel ferrites were found to be 1.8–2.5 eV revealing semiconducting behaviour of the nanocatalysts. Frequency dependent dielectric studies revealed that at high frequency both dielectric constant and dielectric loss were decreased. The photocatalytic degradation (PCD) of the synthesized spinel ferrites with methylene blue (MB) as organic pollutant and their antibacterial activity was also studied. Ca0.2Cu0.8Fe2O4 (CCFO-5) nanocatalyst exhibited 96% degradation in 180 min with methylene blue dye.

This paper reports the impacts of cerium (Ce) substitution on morphological, magnetic and structural characteristics of Mn0.5Zn0.5CexFe2-xO4 (x = 0.0, 0.3 and 0.5) ferrites nanoparticles (NPs) prepared via sol gel combustion method. The crystalline structure, magnetic and morphological features were examined by powder X-ray diffraction, vibrating sample magnetometer and scanning electron microscope analyser individually. Magnetic hysteresis (M−H) loops of samples were determined to examine the magnetic properties of synthesized samples. Magnetic measurement shows that samples exhibit ferromagnetic behaviour at room temperature (RT). The magnetic properties are described in terms of cation substitution and grain size effect. The various concentration of synthesized photocatalyst such as Mn0.5Zn0.5Fe2O4, Mn0.5Zn0.5Ce0.3Fe1.7O4 and Mn0.5Zn0.5Ce0.5Fe1.5O4 NPs were analysed under visible light irradiation by the degradation of an aqueous solution of Congo red and Reactive Orange 16 dyes and the sample Mn0.5Zn0.5Ce0.3Fe1.7O4 NPs showed higher degradation percentage 97.25% and 98.42% respectively, than other compositions at 120 min with enhanced visible light absorption range. These performances expose that these nanomaterials are appropriate for high frequency applications.

In this paper, conductivity, dielectric, and microwave properties of SrNbxYxFe12-2xO19 (0.00 ≤ x ≤ 0.05) hexaferrites (SrNbY HFs) synthesized by the citrate sol–gel method were investigated. Some key parameters compatible with the electrical and dielectric functions of SrNbY HFs have been extensively evaluated as functions of bias frequency, measurement temperature, and co-substitution ratios in logarithmic 3D graphs by complex impedance spectroscopy. It has been observed that although the co-substitution ratio is highly functional on dielectric parameters such as both the dielectric constant and dielectric loss, as well as the dissipation factor, it has a very low influence on the conductivity mechanism. Depending on the substitution ratios of Nb and Y ions and the transition temperature region, the activation energy was calculated to vary between 58 and 476 meV. Microwave properties were measured as S-parameters using a coaxial line in the range of 2–12 GHz. It was analysed the frequency dependences of the real/imaginary parts of the permittivity and permeability for all samples. Reflection losses vs. frequency were calculated as a function of the substitution level. Coefficients of the RL (−12.5 … −16.8 dB) confirm practical importance for electromagnetic compatibility at high frequencies.

Water serves as a key component in the basis of life to function and evolve unceasingly. Excessive deterioration of fresh water resources through discarding enormous amounts of dye effluents is becoming a problem of concern. In this work we report a conventional solid-state technique improved with choline chloride: urea DES medium in 1:2 ratio for synthesizing pure calcium titanate (CTO) and lanthanum doped calcium titanate (LaxCa1-xTiO3; x = 0.0 and 0.5). Both the materials were subjected to photocatalytically degrade reactive dyes RB5, RR198 and RY145. La-doped calcium titanate showed effective degradation efficiency when compared to the pure calcium titanate. On increasing the concentration of the dye, the efficiency of degradation declined gradually. Also, the efficiency was assessed to be greatest for RY145 followed by RR198 and lastly RB5. Efficiency dependence on different pH exposed the enhanced degradation in acidic medium and comparatively lowered pH in basic medium. Recyclability was highly satisfying and promising to validate the real-time applicability of the catalyst.

ZnFe2O4 (ZFO) NPs (nanoparticles), Co0.5Ni0.5Ga0.01Gd0.01Fe1.98O4 (CNGaGdFO) NPs and hard-soft spinel ferrite (H/S) (CNGaGdFO)x/(ZFO)y (x:y = 1:1, 1:2, 1:3, 2:1, 3:1 and 4:1) NCs (nanocomposites) were synthesized via a one-pot sol–gel auto combustion route. X-ray powder diffraction (XRD) analyses confirmed the purity of ZFO NPs, CNGaGdFO NPs and H/S (H/S) (CNGaGdFO)x/(ZFO)y (x:y = 1:1, 1:2, 1:3, 2:1, 3:1 and 4:1) (absence of any second phase). The crystallite size of NCs was between 39 and 52 nm. The cubic morphology was observed for ZFO NPs, CNGaGdFO NPs and all H/S NCs by the help of scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analyses. Energy dispersive X-Ray analysis (EDX) also confirmed the chemical formula of all the NC samples. Electrical and dielectric properties of ZFO NPs, CNGaGdFO NPs and H/S NCs were explored with an impedance analyzer with f ≤ 3.0 MHz, where f stands for frequency, and within the temperature range between 20 and 120 °C. Electric and dielectric parameters such as AC conductivity as well as DC conductivity, activation energy, dielectric constant, dielectric loss in addition to the dissipation parameter relevant to the electrical energy due to different physical processes were measured for each of the given compositional ratios. The AC conductivity was found to follow the frequency-dependent power law in general, being mainly reliant on the compositional ratios and the measured temperatures especially at lower frequencies. This study has shown that CoNiGaGdFeO-ZnFe2O4 H/S NCs carry out conduction mechanisms, which can be predominantly credited to grain–grain boundaries for various compositional ratios. The dielectric constant of (CNGaGdFO)x/(ZFO)y (x:y = 1:1, 1:2, 1:3, 2:1, 3:1 and 4:1) H/S NCs indicates common dielectric behaviours with frequency, largely dependent on compositional rates of the hard to soft spinel ferrites. It is observed that hard ferrite is dominant in the formation of the semicircles, and the diameter of the semicircles shows a drop as the temperature rises, suggesting a temperature-dependent relaxation mechanism. Consequently, the observed variation of the studied dielectric parameters with frequency can be explained by the conduction mechanism in most composition ratios of hard to soft spinel ferrites, which can be explained by a phenomenological method with Koop's model.

Hard/soft (H/S) Sr0.5Ba0.5Eu0.01Fe12O19/NixCuyZnwFe2O4 nanocomposites (NCs) were produced via a one-pot sol–gel auto-combustion procedure. Phase and surface analyses were performed using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and high-resolution transmission electron microscopy (HR-TEM). Magnetization measurements for H/S NCs with different x, y, and w ratios were investigated at two different temperatures (300 and 10 K). The M−H curves were not smooth for the different H/S NCs, revealing that the exchange interaction was incomplete. The derivative of the magnetization (dM/dH versus H) exhibited two separate peaks, confirming the non-coupled H/S mixtures. Maximum saturation magnetization (Ms) values of 93.9 and 63.1 emu/g were obtained at 10 and 300 K, respectively, for the H/S Sr0.5Ba0.5Eu0.01Fe11.99O19/Ni0.3Cu0.3Zn0.4Fe2O4 NC, which contained the highest content of Zn and the same contents of Ni and Cu within the soft magnetic phase. The calculated squareness ratios (SQR = Mr/Ms) were less than 0.5, indicating incomplete exchange coupling. The coercive field (Hc) of the produced NCs reached a maximum value of approximately 2485 Oe at 300 K and 2331 Oe at 10 K with a decrease in the Ms values to 56.9 emu/g at 300 K and 78.5 emu/g at 10 K for the H/S Sr0.5Ba0.5Eu0.01Fe11.99O19/Ni0.8Cu0.1Zn0.1Fe2O4 NC, which contained lower fractions of Zn and Cu and the highest fraction of Ni. The reflection/transmission-based waveguide approach was employed to investigate the electrodynamic properties of the H/S NC samples within a frequency band of 7–18 GHz. The reflection and transmission coefficients (S11/S21) were measured using a vector network analyzer (VNA) for the sample placed inside a waveguide. The frequency dispersions of the magnetic permeability and electric permittivity were calculated.

The effects of Ce–Dy co-doping on the crystal structure, optical, dielectric, magnetic properties, and hyperfine interactions of Ni–Co spinel ferrite microspheres synthesized hydrothermally have been studied. A series of ferrites with the general formula Ni0.5Co0.5CexDyxFe2-2xO4 were synthesized with x values ranging from 0.00 to 0.10. The phase, crystallinity, and morphology of ferrite microspheres were analyzed by X-ray powder diffractometry (XRD), scanning and transmission electron microscopes (SEM and TEM), respectively. The structural analyses of the synthesized ferrite microspheres confirmed their high purity and cubic crystalline phase. The Diffuse reflectance spectroscopic (DRS) measurements were presented to calculate direct optical energy band gaps (Eg) and is found in the range 1.63 eV - 1.84 eV. 57Fe Mossbauer spectroscopy showed that the hyperfine magnetic field of tetrahedral (A) and octahedral (B) sites decreased with the substitution of Dy3+-Ce3+ ions that preferrentially occupy the B site. The impact of the rare-earth content (x) on the magnetic features of the prepared NiCo ferrite microspheres was investigated by analyzing M-H loops, which showed soft ferrimagnetism. The magnetic features illustrate a great impact of the incorporation of Ce3+-Dy3+ ions within the NiCo ferrite structure. The saturation magnetization (Ms), remanence (Mr), and coercivity (Hc) increased gradually with increasing Ce–Dy content. At x = 0.04, Ms, Mr, and Hc attain maximum values of about 31.2 emu/g, 11.5 emu/g, and 512.4 Oe, respectively. The Bohr magneton (nB) and magneto-crystalline anisotropy constant (Keff) were also determined and evaluated with correlation to other magnetic parameters. Further increase in Ce3+-Dy3+ content (i.e., x ≥ 0.06) was found to decrease Ms, Mr, and Hc values. The variations in magnetic parameters (Ms, Mr, and Hc) were largely caused by the surface spins effect, the variations in crystallite/particle size, the distribution of magnetic ions into the different sublattices, the evolutions of magneto-crystalline anisotropy, and the variations in the magnetic moment (nB). The squareness ratios were found to be lower than the predicted theoretical value of 0.5 for various samples, indicating that the prepared Ce–Dy substituted NiCo ferrite microspheres are composed of NPs with single-magnetic domain (SMD). Temperature and frequency-dependent electrical and dielectric measurements have been done to estimate the ac/dc conductivity, dielectric constant, and tangent loss values for all the samples. The ac conductivity measurements confirmed the power-law rules, largely dependent on Ce–Dy content. Impedance analysis stated that the conduction mechanisms in all samples are mainly due to the grains-grain boundaries. The dielectric constant of NiCo ferrite microspheres give rise to normal dielectric distribution, with the frequency depending strongly on the Ce–Dy content. The observed variation in tangential loss with frequency can be attributed to the conduction mechanism in ferrites, like Koop's phenomenological model.

Abstract Indium-substituted strontium hexaferrites were prepared by the conventional solid-phase reaction method. Neutron diffraction patterns were obtained at room temperature and analyzed using the Rietveld methods. A linear dependence of the unit cell parameters is found. In3+ cations are located mainly in octahedral positions of 4fVI and 12 k. The average crystallite size varies within 0.84–0.65 μm. With increasing substitution, the TC Curie temperature decreases monotonically down to ~ 520 K. ZFC and FC measurements showed a frustrated state. Upon substitution, the average and maximum sizes of ferrimagnetic clusters change in the opposite direction. The Mr remanent magnetization decreases down to ~ 20.2 emu/g at room temperature. The Ms spontaneous magnetization and the keff effective magnetocrystalline anisotropy constant are determined. With increasing substitution, the maximum of the ε/ real part of permittivity decreases in magnitude from ~ 3.3 to ~ 1.9 and shifts towards low frequencies from ~ 45.5 GHz to ~ 37.4 GHz. The maximum of the tg(α) dielectric loss tangent decreases from ~ 1.0 to ~ 0.7 and shifts towards low frequencies from ~ 40.6 GHz to ~ 37.3 GHz. The low-frequency maximum of the μ/ real part of permeability decreases from ~ 1.8 to ~ 0.9 and slightly shifts towards high frequencies up to ~ 34.7 GHz. The maximum of the tg(δ) magnetic loss tangent decreases from ~ 0.7 to ~ 0.5 and shifts slightly towards low frequencies from ~ 40.5 GHz to ~ 37.7 GHz. The discussion of microwave properties is based on the saturation magnetization, natural ferromagnetic resonance and dielectric polarization types.

Some new types of Ce3+ and Dy3+ co-doped manganese-zinc nanospinel ferrites (CDMZNSFs) of the form (Mn0.5Zn0.5)[Fe2-2xCexDyx]O4 (with 0.0 ≤ x ≤ 0.1) were sonochemically produced and characterized. The structure, morphology, optical and magnetic properties of these NSFs were determined as a function of co-dopant (Ce3+ and Dy3+) contents. The direct optical band gap energies of the studied NSFs were ranged from 1.54 to 1.85 eV. The measurements of magnetization versus magnetic field of the prepared NSFs disclosed a superparamagnetic (SPM) behavior at room temperature (RT). The measurements of temperature-dependent magnetizations revealed a transition from superparamagnetic (SPM) state above blocking temperature TB to a ferromagnetic (FM) state below TB. The saturation magnetization and TB decreased with the increase in co-dopant contents. In addition, the bactericidal (on the gram-positive and gram-negative bacterial strains) and anti-cancerous effectiveness of these NSFs were assessed. The cancer cells' growth inhibitory action of these NSFs was tested against both normal (HEK-293) and cancerous (HCT-116) human cells. After 48 h of treatment of the cancerous cells with the NSFs, their population was significantly dropped as shown by the MTT assay, indicating the selective inhibition of the cancer cells growth by the proposed NSFs. Conversely, the non-cancerous cells (HEK-293) population remained unaffected. The IC50 values of the NSFs-treated cancerous cells (HCT-116) were in the range of 0.74–2.35 µg/mL. The results of the MIC and MBC assays revealed the reasonable antibacterial efficacy (growth inhibitory activity) of these NSFs when tested against the E. coli and S. aureus bacterial strains. It is established that the proposed Ce3+/Dy3+ co-activated CDMZNSFs may be beneficial for the anti-cancerous and bactericidal applications.

Partially Nd/Y substituted [Ni0.4Cu0.2Zn0.4](NdxYxFe2-2x)O4 (x ≤ 0.05) spinel ferrite nanoparticles (NSFs) were prepared by citrate sol-gel auto-combustion technique. UV–vis Percent to determine optoelectronic properties mixed spinel ferrite materials. Direct energy band gaps values are within 1.87 and 1.92 eV interval. The magnetization features were investigated at room temperature (RT; T = 300 K) versus magnetic field ((M-H)). RT M-H curves showed superparamagnetic (SPM) behavior in non-substituted sample (x = 0.00), while all the Nd-Y substituted NiCuZn ferrite NPs exhibited soft ferrimagnetic (FM) character. It is found that the magnitude of magnetization drops with a rise in Nd3+ and Y3+ contents. ZFC–FC magnetization curves revealed the existence of dipolar interactions, which illuminate a partially blocked state in accordance with M-H loops at 300 K. The electrodynamic data reflection coefficients for Ni0.4Cu0.2Zn0.4](NdxYxFe2-2x)O4 (x ≤ 0.05) NSFs were determined. The occurrences of the electromagnetic absorption between 49 to 4.15 GHz frequency range were observed. A significant linking amongst the ratio (x) and amplitude-frequency characteristics (AFC) was investigated. Additionally, the AFC of the Ni0.4Cu0.2Zn0.4](NdxYxFe2-2x)O4 (x ≤ 0.05) NSFs were strongly influenced with the increase of Nd/Y concentration. It was demonstrated that low level of the concentration substitution (less than 10 at.%) not critically effected on resonance characteristics. We found that an anomalous altering of the resonant amplitude (almost 2 times) resulted due the manifestation of indirect exchange interactions amongst iron (III), yttrium (III) and neodymium (III) electronic shells. Almost a linear behavior of the main AFC was observed.

Tb-substituted Ni0.4Cu0.2Zn0.4TbxFe2−xO4 (0.0 ≤ x ≤ 0.10) nanospinel ferrites were formed by sonochemical technique. It was first time established correlation between chemical composition of the nanosized NiCuZn spinels and their structural, electrical and microwave properties. The structure of nanospinel ferrites (NSFs) was proved through XRD. Microstructural were analyzed from SEM. It was observed a non-linear dependence of the average grain size with Tb concentration. The conduction mechanism and dielectric function has been extensively studied as functions of frequency, temperature, and Tb ions substitution ratio using complex impedance spectroscopy. It is obvious to see that the substitutions ratio showed a substantial influence on dielectric features, while Tb ion substitution has little but notable effect on AC/DC conductivity change. From the Arrhenius plots, the activation energies for all substitution ratios were calculated. The reflection losses as a function frequency dependences of the were calculated from S-parameters data within 1–4.5 GHz. The occurrences of the electromagnetic absorption in the frequency interval of 1.85–3.79 GHz were observed. Non-linear behaviour of the amplitude–frequency features were verified as a function of the level of chemical substitution (x) with Tb ions concentration. It was found microstructural parameters correlates well with the main absorption characteristics. It was discussed the nature of the electromagnetic absorption for partially substituted nanospinels. The decline of the reflected electromagnetic radiations was explicated along with domain-boundary resonance, which well correlates with the microstructure data. The low dimensional magnetic oxides having the domain-boundary resonance have a role in nature of absorption.

This paper reports the synthesis, structural characteristics and magnetism of SrFe12O19/MCe0.04Fe1.96O4 (M = Cu, Ni, Mn, Co and Zn) hard/soft nanocomposites. The hard/soft compositions were manufactured via a one-pot reactions citrate sol-gel approach. The hard/soft phases formation was confirmed using XRD, SEM, TEM and HRTEM techniques. M vs. H (Magnetization measurements) were done at unbent temperature and 10 K. Smoothed M against H loops and single peaks in dM/dH vs. H curves were noticed in SrFe12O19/MnCe0.04Fe1.96O4, SrFe12O19/CuCe0.04Fe1.96O4 and SrFe12O19/ZnCe0.04Fe1.96O4 hard/soft nanocomposites. This indicated the manifestation of well exchange-coupled effect among hard and soft phases in these composites. However, SrFe12O19/CoCe0.04Fe1.96O4 and SrFe12O19/NiCe0.04Fe1.96O4 hard/soft nanocomposites showed non-well smoothed M against H loops and two peaks in dM/dH versus H plots, indicating that the dipolar interactions are unimportant compared to exchange-coupling behavior. Among all prepared nanocomposites, the SrFe12O19/MnCe0.04Fe1.96O4 hard/soft nanocomposite showed the highest exchange-coupling behavior. Microwave properties of the SrFe12O19/MCe0.04Fe1.96O4 (M = Cu, Ni, Mn, Co and Zn) hard/soft nanocomposites were investigated using coaxial method with applied frequency values fall between 2 and 18 GHz. Reflection losses were calculated from frequency dependences of the imaginary and real parts of permeability and permittivity. The correlation between the chemical composition of the spinel phase (A-cation) and microwave properties of composites. Most intensive electromagnetic absorption was observed for Ni- and Mn-spinels. This is can be a result of the differences in electron shell configuration and radii for A-site ions in the spinel phase. Change of the absorption mechanisms (transition from ionic polarization to dipole polarization) was observed.

In the present work, an experimental study is performed to study the radiation shielding characteristics of SrTiO3 (STO) perovskite ceramic added with different amounts (x = 0, 2, 5, and 10%) of tungsten trioxide nanoparticles (WO3 NPs). The four ceramic samples were prepared using the solid-state reaction method. The structural properties were examined using X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) techniques. The analysis showed the successful formation of WO3- doped STO samples. The crystallite size, estimated using the Scherrer equation, was found in the range of 50.86–41.17 nm. The effect of WO3 NPs on the radiation shielding performance of these ceramics was studied. Different parameters, such as linear attenuation coefficient (LAC) and other related factors, were experimentally determined. The linear attenuation coefficient results demonstrated that the additional amount of WO3 in the ceramics correlates with an improvement in their shielding abilities. The half-value layer (HVL) values for the ceramics with 2% WO3 nanoparticles are equal to 0.071, 1.760, 2.407, and 2.564 cm at 0.060, 0.662, 1.173, and 1.333 MeV, respectively. As the energy increases, more radiation can pass through the material; therefore, a larger thickness is required to absorb half of the total photons, leading to a greater HVL. The tenth value results reaffirmed that increasing the WO3 content in the STO ceramics improves their shielding efficiency. The radiation protection efficiency (RPE) of the four prepared STO ceramics was reported. From the RPE, we found that more photons can be attenuated at lower energies.

ZnxCa0.5-x/2Mg0.5-x/2Fe2O4 (x = 0.0–0.6) nano-spinel ferrite (NSFs) were prepared by ultrasonic irradiation with Moringa oleifera leaf extract (group A) and without Moringa oleifera leaf extract (group B). The synthesis done with Moringa oleifera leaf extract is green synthesis. The structure and morphologies of both group A and B NSFs were investigated by XRD, SEM, TEM, and FT-IR in details. The crystallite sizes of group A and B products were calculated as within the range of 11–17 nm and 16–28 nm, respectively. The magnetic features of different nanoparticles of group A and B NSFs have been investigated at room (T = 300 K) and low (T = 10 K) temperatures by means of a vibrating sample magnetometer (VSM). All samples displayed superparamagnetic (SPM) behavior at room temperature, with no or negligible coercivity and retentivity. Nevertheless, the different samples revealed opened M−H hysteresis loops at a temperature of 10 K, which indicates their ferromagnetic (FM) behavior at very low temperatures. The various magnetic parameters including the saturation magnetization (Ms), remanent magnetization (Mr), squareness ratio (Mr/Ms), magneton number (nB), coercive field (Hc), etc. were extracted. The ZnxCa0.5-x/2Mg0.5-x/2Fe2O4 (x = 0.0 – 0.6) NSFs prepared using Moringa oleifera extract (Group A samples) displayed lower Ms values in comparison to NSFs prepared without using Moringa oleifera extract (Group B samples). Whereas, the coercivity is found to be larger in Group B samples than in Group A samples. These is mainly ascribed to the variations in particles size upon the use of Moringa oleifera extract. Compared to non-substituted Ca0.5Mg0.5Fe2O4 NSFs, it is noticed that the Ms value increases with Zn2+ ions substitution. The increase of Ms value is ascribed to the strengthening of exchange interactions and redistribution of cations (particularly Fe3+ ions) within the spinel lattice. At T = 10 K, the Hc value decreases with the rise of the Zn2+ content, which is attributed to the larger crystallites/particles that lead to the lower volume fraction of grains boundaries, which in turn conduce to less pinning of domain walls. The SQR values at 10 K for all NSFs of group A and B are between 0.2 and 0.3, which is below the theoretical limit of 0.5, reflecting the NPs consist of multi-magnetic domains. The obtained magnetic properties of group A NSFs are interesting, suggesting that this method could be considered as an alternative and effective green synthesis route with appropriate control of size, morphology, and physical features of magnetic nanoparticles.

This paper studied the exchange coupling performance beside structural and microwave properties of SrFe12O19 (SFO) and x(CoTm0.01Tb0.01Fe1.98O4) (CoTmTb) (x ≤ 3.0) hard/soft ferrites nanocomposites (NCs). The structure and morphology of NCs were investigated by XRD, SEM, TEM and HR-TEM. Diffuse reflectance spectroscopic (DRS) measurements were applied on hexagonal ferrite, on spinel ferrite nanoparticles and on hard/soft NCs to specify the optical properties. Estimated Eg data are in a range between 1.32 and 1.79 eV. The magnetic properties were also inspected via measurements of magnetization (M) against magnetic field (H) at 300 K (RT) and 10 K (LT). The measurements performed at RT along with the plots of dM/dH versus H indicated that the NCs display good magnetic properties (exchange coupling behavior). The magnetic parameters such as (Ms, Mr, and Hc) show an enhancement in their values with an increasing the soft content at RT. Similarly, the maximum energy product (BH)max rises and reaches its max value for SFO/3(CoTmTb) NCs. Microwave properties of the SFO/x(CoTmTb) NCs were measured in the frequency range 33–50 GHz. From measured S11 and S21 parameters the main electrodynamic characteristics – permittivity and permeability (real and imaginary parts) were computed.

The demand of the multifunctional nanospinel ferrites (NSFs) is ever-increasing for various advanced applications wherein the fundamental knowledge of the magnetic features became essential. In this view, high purity NSFs of composition (Mn0.5Zn0.5)[EuxNdxFe2-2x]O4 (0.00 ≤ x ≤ 0.05) were synthesized via the ultrasonic irradiation. The influence of the co-substituents (Eu3+/Nd3+) concentration on the microstructures, morphologies and magnetic behaviors of these as-prepared NSFs were evaluated. The samples were characterized thoroughly using diverse analytical instruments. The X-ray powder diffraction patterns of these NSFs verified their phase purity. The SEM and TEM analyses revealed the existence of spherical shaped grains with size around 20 nm. The produced NSFs showed a superparamagnetic (SPM) behavior at room temperature and ferromagnetic (FM) behavior at very low temperatures. Both saturation and remanent magnetization values of the studied NSFs were improved at lower Eu3+/Nd3+ contents up to x = 0.02 and then dropped beyond x > 0.02. It was shown that the magnetic traits of these NSFs can be tailored by controlling the Eu3+/Nd3+ concentrations.

Green and facile process for Ni0.4Cu0.2Zn0.4Fe2−xEuxO4 (x = 0.00–0.10) spinel ferrite nanoparticles (SNPs) prepared via ultrasonic irradiation (without any post annealing process) has been deeply investigated. The influence of Eu3+ substitutions on the structure, morphological, optical, magnetic, electrical and dielectric traits of NiCuZn SNPs was assessed. Tauc plots revealed direct optical band gaps in a very tight interval of 1.86–1.90 eV. Magnetization measurements exposed a superparamagnetic behavior at room temperature and below the blocking temperature (TB) a superparamagnetic-ferromagnetic transition was noticed. The saturation magnetization (Ms) value is highest for pure Ni0.4Cu0.2Zn0.4Fe2O4 (i.e. x = 0.00) SNP with Ms ~ 58.9 emu/g at room temperature. The saturation magnetization (Ms) declines with rising Eu3+ substituting content. AC conductivity decreases as a function of exponent power base law. Maximum variation in dc conductivity is observed to be around the substitution ratio of x = 0.02. It is found that activation energy is highly dependent on both Eu ions substitution ratios and temperature ranges. The frequency dependence of dielectric functions is explained by Koop's models based on Maxwell-Wagner theory.

The present work describes the effect of Ce3+ ion doping on the structural, morphological, and magnetic properties of spinel manganese ferrite (MnFe2O4) nanocrystallites (NCs) using various instrument techniques. Rare earth element (REE) Cerium (Ce3+) doped MnFe2O4 NCs were prepared by a simple microwave combustion technique. In the present scenario, ferrites are widely used for photocatalytic dye degradation and antibacterial applications. Aiming to achieve this, we prepared Ce3+ doped MnFe2O4 NCs by microwave combustion method and urea as burning agent and the obtained powder samples were characterized by powder X-ray diffraction (XRD), Fourier transform infrared (FT-IR), high resolution scanning electron microscope (HR-SEM), high resolution transmission electron microscope (HR-TEM) and vibration sample magnetometer (VSM) techniques. The pure spinel phase formation was confirmed by XRD analysis. FTIR spectra show two prominent absorption bands under 1000 cm−1, which confirms the formation of the spinel structure. HR-SEM and HR-TEM pictures demonstrated a sphere-shaped morphology and also expose the combination and agglomeration of grains, which are mostly due to the magnetic characteristics of the samples. The magnetic properties of the synthesized MnCexFe2−xO4 (x = 0.0, 0.1, 0.3, and 0.5) NCs were studied by VSM analysis at room temperature (RT) shows ferromagnetic behavior. The photodegradation results showed that MnFe2O4 and Ce doped MnFe2O4 NCs have a higher potential to degrade methylene blue (MB) and the sample MnCe0.3Fe1.7O4 NCs showed superb photocatalytic performance (91.53%) compared to other samples. The antibacterial activities of Gram-positive S. aureus, B. subtilis and Gram-negative K. pneumonia and E. coli were investigated using pure and Ce3+ substituted MnFe2O4 NCs and a higher activity for MnCe0.3Fe1.7O4 NCs than other samples was observed, which indicated that they can be used in biomedical applications.

La–Y substituted Ni-Cu-Zn nanospinel ferrites (NSFs) having the following formula Ni0.3Cu0.3Zn0.4LaxYxFe2−2xO4 (x = 0.0–0.10) were fabricated prepared by ultrasonic irradiation approach. The X-ray powder diffractometer (XRD), scanning electron microscope (SEM) and Fourier-transform infrared spectroscopy (FT-IR) were utilized to analyze the structure, vibration bands and morphology. The impedance spectroscopy technique was used for the analysis of electrical and dielectric properties of La3+ and Y3+ ions co-substituted Ni0.3Cu0.3Zn0.4Fe2O4 NSFs. Some important parameters such as ac conductivity, activation energy, dielectric constant and dielectric loss were examined as functions of frequencies and temperatures for a variety of La and Y co-substitution ratios. In general, ac conductivity is observed to fluctuate slightly with the elevated temperatures while its fluctuation level decreases somehow with an increase in co-substitution ratios. Furthermore, the frequency dependence of dielectric functions could be described by Koop's models based on Maxwell-Wagner theory, which elucidates the correlation between the polarizability coefficient and dielectric constant in inhomogeneous double-layer structures. Keywords: Spinel ferrites, Rare earth substitutions, Conductivity, Dielectric properties

Single phase of BaFe12-xNbxO19 (x ≤ 0.1) hexaferrites (HFs) were fabricated via citrate sol-gel route. The Ba hexaferrite formation has been confirmed by XRD and FE-SEM. The conductivity and dielectric properties of some Nb3+ions-substituted BaFe12O19 hexaferrites (Ba-HFs) were studied extensively via impedance spectroscopy. Some important parameters; dielectric constant, conductivity, dielectric loss, complex modulus and dissipation factors were analysed at temperatures up to 120 °C in 1.0 Hz to 3.0 MHz in frequency interval for various Nb substituents. Frequency dependent conductivity was found to be in accordance with the power laws with various exponents in all frequencies studied here. Such variation can be attributed to a characteristic conduction mechanism based on tunnelling processes. Furthermore, it is clear that the contribution of the dielectric response to the dielectric parameters between grains and grain boundaries can be interpreted in a certain frequency range. Keywords: Barium hexaferrite, Structure, Electrical conductivity, Dielectric properties

Hexaferrite (HFs) of Sr1−xZrxFe12O19 (0.00 ≤ x ≤ 0.10) have been produced through Citrate Sol-gel approach. The characteristic of compositions is studied through XRD (X-ray powder diffractometer), SEM (Scanning electron microscopy), EDX (Energy-dispersive X-ray), TEM (Transmission electron microscopy), DR% (UV–Visible diffuse reflectance spectrophotometer), FT-IR (Fourier transform infrared spectrophotometer). The single-phase Sr hexaferrite was confirmed for each product by XRD. The crystallites size of the products was calculated as 22–40 nm range which makes this material as an appropriate candidate for high density recording media. The optical band gap tends to decrease when increasing the Zr content. The analyses of magnetization versus applied magnetic field, M(H), were performed at room (300 K; RT) and low (10 K) temperatures. The various magnetic parameters including coercivity Hc, squareness ratio (SQR = Mr/Ms), remanence Mr, saturation magnetization Ms and magnetic moment nB were deduced and described in detail. At both considered temperatures, the M(H) results showed ferrimagnetic nature. It is showed that the Zr substitutions significantly affect the magnetizations data. A significant decrease in the Ms, Mr, and nB was observed with Zr substitution. Keywords: Sr hexaferrite, Zr substitution, Structure, Optical properties, Magnetic properties

SrTmxFe12−xO4 (0.00 ≤ x ≤ 0.10) hexaferrites (HFs) are produced successfully using a sol–gel approach. The structural, optical, and magnetic properties are investigated. The hexagonal phase is confirmed for all the products. The magnetization is measured with respect to the applied magnetic field, M(H). The magnetic parameters including saturation magnetization Ms, remanence Mr, squareness ratio (SQR = Mr/Ms), coercivity Hc, and magnetic moment nB are deduced at room (300 K; RT) and low (10 K) temperatures. It is shown that the ferrimagnetic nature and Tm3+ substitutions lead to decreases in the magnetization and coercivity magnitudes. The results on magnetic properties are investigated extensively with respect to the structural and microstructural properties. The SQR values indicate the formation of a single magnetic domain for the x = 0.0 sample and a multi-magnetic domain structure for the Tm3+-substituted Sr HFs (x ≥ 0.02). The obtained Hc values suggest that the produced HFs are promising candidates for potential magnetic recording applications. Keywords: Hexaferrites, Tm substitution, Mossbauer study, Magnetic properties, Optical study, Cation distribution

The Nb3+ ion substituted Sr hexaferrites (SrNbxFe12−xO19 (x = 0.00−0.08) hexaferrites (HFs)) were fabricated via a citrate-assisted sol-gel approach. X-ray powder diffractometer analysis affirmed the pureness of all products. The crystallite sizes of the products which were estimated from Scherrer equation were in the 36−40 nm range. The chemical component of the samples was proved by Energy-dispersive X-ray spectroscopy (EDX) and Elemental mapping. The hexagonal morphology of all products was confirmed by Field Emission Scanning Electron Microscopy (FE-SEM). The electrical conduction mechanisms and dielectric properties of a variety of Nb3+ions-substituted SrNbxFe12−xO19 HFs were investigated by a complex impedance system. Dielectric parameters such as conductivity, dielectric constant, dielectric loss, dielectric tangent loss and complex modulus, were studied at temperatures up to 120 °C in a frequency range varying from 1.0 Hz to 3.0 MHz for several Nb ratios. The frequency dependence of the conductivity was found to comply with the power law with diverse exponents at all frequencies studied here. Subsequently, incremental tendencies in dc conductivity with temperature indicate that the substituted Sr-HFs leads to a semiconductor-semimetal like behavior. This could be attributable to a feature of conduction mechanism which is based on the tunneling processes. Additionally, the dielectric dispersion pattern was also explained by Maxwell−Wagner polarization in accordance with the Koop’s phenomenological theory.

This paper reports the influence of dysprosium ion (Dy3+) substitution on the structural and magnetic properties of NiDyxFe2−xO4 (0.0 ≤ x ≤ 0.1) nanoparticles (NPs) prepared using a hydrothermal method. The structure and morphology of the as-synthesized NPs were characterized via X-ray diffraction (XRD), scanning and transmission electron microscope (SEM, and TEM) analyses. 57Fe Mössbauer spectra were recorded to determine the Dy3+ content dependent variation in the line width, isomer shift, quadrupole splitting, and hyperfine magnetic fields. Furthermore, the magnetic properties of the prepared NPs were also investigated by zero-field cooled (ZFC) and field cooled (FC) magnetizations and AC susceptibility measurements. The MZFC (T) results showed a blocking temperature (TB). Below TB, the products behave as ferromagnetic (FM) and act superparamagnetic (SPM) above TB. The MFC (T) curves indicated the existence of super-spin glass (SSG) behavior below Ts (spin-glass freezing temperature). The AC susceptibility measurements confirmed the existence of the two transition temperatures (i.e., TB and Ts). Numerous models, e.g., Neel−Arrhenius (N−A), Vogel−Fulcher (V−F), and critical slowing down (CSD), were used to investigate the dynamics of the systems. It was found that the Dy substitution enhanced the magnetic interactions.