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Extensive investigations have been conducted on high-entropy oxides (HEOs) as promising materials for heat conversion. In this study, a novel high-entropy ferrite (Mn 0.2 Co 0.2 Cu 0.2 Zn 0.2 Mo 0.2)Fe 2 O 4 with a spinel structure was synthesized via the solid-state method at elevated temperatures, and its thermoelectric properties were subsequently evaluated. The XRD, SEM, and TEM-EDS measurements demonstrate the successful incorporation of multi-component cations into a single site, leading to the formation of a homogeneous material phase. Furthermore, TEM analysis reveals the presence of various defects and lattice distortions such as dislocations in this high-entropy ceramic. At 1073K, the high-entropy ceramic exhibits a low thermal conductivity (κ = 1.74 W/m/K) and a high Seebeck coefficient (|S| = 180.5 μV/K). The results suggest that high entropy engineering has the potential to enhance the thermoelectric properties of spinel structured ferrites, thereby creating exciting prospects for utilizing this spinel ferrite as a novel thermoelectric material in high-temperature applications. [ABSTRACT FROM AUTHOR]

Properties of root weld are important for service safety of pipelines, while microstructure and properties of root weld would alter due to heat affect of following welding passes. Evolution of root weld microstructure and properties during automatic girth welding of X80 pipeline was studied. Microstructure of the original root weld primarily consists of acicular ferrite (AF) and side-plate ferrite (SPF), and it is mostly affected by hot pass and first filling pass weld, after which SPF and AF coarsened significantly and some interlock ferrite combined with each other. During subsequent welding, no significant microstructural changes was found. However, impact toughness of root weld slightly increased after hot pass and first filling pass in spite of microstructure coarsening. In contrast, hardness of root weld notably dropped due to microstructure coarsening of hot pass and first filling pass, and then it was retrieved in following welding passes due to tempering effect. [ABSTRACT FROM AUTHOR]

Nanocomposites of SrBi (2-X) (CF) X Nb 2 O 9 (SBNCF) (CF=CoFe 2 O 4 for X = 0.0 to 0.5 with a step increment of 0.1) were synthesized using the hydrothermal method and characterized for their structural, morphological, elastic, and optical properties. The incorporation of CF into SrBi 2 Nb 2 O 9 (SBN) resulted in hybrid composites with tailored properties. X-ray Diffraction (XRD) with Rietveld refinement analysis confirmed the formation of orthorhombic SBN and spinel CF phases. Field Emission Gun Scanning Electron Microscopy (FEG-SEM) revealed that SBN exhibits a plate-like morphology, with the incorporation of CF into the SBN matrix resulting in both plate-like and octahedral-shaped grains. The Brunauer–Emmett–Teller (BET) method was used to determine the pore radius and surface area, both of which were found to have increased, indicating an enhancement in photocatalytic performance. The presence of the constituent elements in the prepared compositions was confirmed by Energy Dispersive Spectroscopy (EDS). Fourier Transform Infrared Spectroscopy (FTIR) spectra were used to determine elastic properties, suggesting potential applications in electronic noise filtering. From Diffuse Reflectance Spectroscopy (DRS), a recognizable semiconducting behavior and band gap bowing were noticed in SBNCF nanocomposites on the obtained energy band gap values (2.20 eV–1.56 eV) compared to the SBN host matrix (3.16 eV). The materials exhibited strong emission peaks at 470 nm, 528 nm, 584 nm, and 703 nm upon the excitation of 425 nm light using Photoluminescence (PL) spectroscopy. The white emission was predominant at room temperature in all the produced samples and the corresponding color temperature values range from 5865.93 K to 7599.05 K from the CIE diagram. The SBNCF materials are promising candidates in photocatalytic reactions and white light-emitting diodes (w-LEDs) based on their enhanced optical properties. [ABSTRACT FROM AUTHOR]

Traditional soft ferrite manufacturing is limited to simple geometries and materials, while 3D printing offers greater flexibility for complex designs. Notably, soft ferrites are crucial for magnetic couplers (pads) in inductive power transfer (IPT) systems to achieve efficient wireless power transmission. The adoption of soft ferrite 3D printing in IPT systems could lead to significantly improved magnetic coupler design, yet research in this area is limited. Hence, the paper first makes a comprehensive comparison of the existing soft ferrite 3D printing methods to ascertain their suitability for magnetic couplers in IPT systems, and then proposes the binder jetting (BJT) as a potential 3D printing approach that could be appropriate for IPT magnetic coupler implementation being versatile, cost‐effective, and suitable for large‐scale manufacturing with high precision. This paper explores the suitability of BJT by 3D printing toroid cores with Mn–Zn ferrite powder under different sintering temperature profiles. Experimental results are presented to show that toroid cores can be 3D printed with high printing precision, mechanical strength, and a relative permeability of 10. This paper also highlights the impact of sintering temperature on 3D‐printed cores, the challenges, limitations, and future research directions of soft ferrite 3D printing for IPT magnetic couplers by the BJT method. [ABSTRACT FROM AUTHOR]

This work describes the synthesis, characterization, and photocatalytic evaluation of a polypyrrole-reinforced zinc-nickel mixed metal ferrite (PPy@ Zn 0.5 Ni 0.5 Fe 2 O 4) nanohybrid. A facile hydrothermal process is employed to synthesize the nanostructured zinc-nickel mixed metal ferrite (ZNF), and in situ oxidative polymerization is utilized to create the PPy nanohybrid. In this nanohybrid, PPy plays multiple roles: preventing charge recombination, reducing photocorrosion, mitigating particle aggregation in ZNF, and enhancing charge transfer and visible light absorption. The combined electron-capturing ability, intrinsic conductivity, and extensive π-conjugation of PPy, along with the magnetic nature of ZNF, render the PPy@ZNF catalyst highly efficient. The results of photoluminescence, impedance, and UV/Vis analysis confirm that PPy plays a critical role in enhancing photocatalytic performance by facilitating charge transfer and extending visible-light absorption. In practical environmental applications, the PPy@ZNF nanohybrid demonstrated superior photocatalytic activity compared to ZNF alone, degrading 98.5 % of malachite green dye under W-lamp light within 80 min, with a rate constant of 0.031 min−1. Scavenger and cyclic experiments identified the active species involved in dye degradation and assessed the reusability of the nanohybrid. Extensive testing revealed the optimal conditions for photocatalytic efficiency; the considered variables included light intensity, catalyst dose, dye concentration, temperature, irradiation time, and pH. These findings suggest that the PPy-reinforced ZNF nanohybrid offers cost-effectiveness, magnetic recoverability, structural stability, and high efficacy as a visible light-driven catalyst, making it a promising candidate for diverse environmental remediation applications. [Display omitted] [ABSTRACT FROM AUTHOR]

Due to the advancement of industrialization, water pollution has become an alarming global issue. Many organic dyes, such as crystal violet and rhodamine B, present in industrial wastewater are causing severe health problems. Both of these dyes are carcinogenic. For their degradation, ferrites are synthesized in this research. Ferrites have high absorbing potential in visible regions and fast movement of charge carrier species. Therefore, the ferrites are potentially used in photocatalysis to purify contaminated water. Graphitic carbon nitride shows enhanced separation of charges, which lowers the rate of recombination of charge carrier species. Lithium nickel ferrite, lithium nickel ferrite doped with terbium, and its composite with graphitic carbon nitride (g-C 3 N 4) are synthesized by sol-gel and ultra-sonication methods, respectively. The prepared samples are analyzed by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, Scanning electron microscopy (SEM), Electrochemical impedance spectroscopy (EIS), and Mott-Schottky analysis. The bandgap of LiNiFe 2 O 4 and LiNiTbFe 2 O 4 was 2.35 eV, and 1.87 eV, respectively. LiNiTbFe 2 O 4 @g-C 3 N 4 degraded 86 % crystal violet and 83 % rhodamine B in 120 min. The LiNiTbFe 2 O 4 @g-C 3 N 4 composite showed the maximum degradation and can be potentially used in wastewater treatment. [ABSTRACT FROM AUTHOR]

Ferrite samples with enhanced magneto-dielectric properties are more essential in electromagnetic applications. Therefore, a parent composition of Fe 3 O 4 has been modified by substituting 3 d transition metal elements (Co, Ni, Mn) at a single Fe atom using the co-precipitation synthesis method. The structural properties of the synthesized Fe 3 O 4 , NiFe 2 O 4 , CoFe 2 O 4 , and MnFe 2 O 4 samples have been evaluated from the X-ray diffraction patterns. The surface morphology and microstructures of the studied samples were studied by field emission scanning electron microscopy and the average grain size of all the studied samples varied from 60.11 to 106.03 nm. The magneto-dielectric properties were analyzed by frequency dependent permeability (μ) and permittivity (ε) measurements for the range of 100 Hz to 100 MHz. The conduction process for the synthesized ferrites has been noticed from the ac conductivity (σ ac). The localized relaxation mechanism for the studied ferrites has been observed from the variation of imaginary portion of the electric modulus (M") and the impedance (Z"). Moreover, the mismatch (Z/η ο) between the impedance of the antenna substrates (Z) made of the studied samples and air (η ο) has been evaluated from the permeability and permittivity. Finally, NiFe 2 O 4 has been derived as a suitable ferrite for miniaturizing devices over a frequency range of 10 kHz-6.5 MHz. [ABSTRACT FROM AUTHOR]

The differences of 0.032% and 0.066% sulfur content on the splitting fracture and machining properties of microalloyed medium-carbon steel 36MnVS4 were studied. The splitting fracture and machining properties were examined by the analysis of MnS inclusions and microstructure, the test of mechanical properties and cutting properties. The results showed that as the number of MnS inclusions increased from 127.3 to 349.8 piece/mm2, the product of strength and elongation of 0.066%S steel increased by 12.3%. The functions of MnS as the core of the intragranular ferritic and refining of the austenite grains resulted in the increase in ferrite content by 2.0%, the decrease in ferrite size by 0.5 μm and the decrease in proto-austenite size by 6.0 μm. A higher ferrite content and lower ferrite and proto-austenite size enhanced the plasticity and toughness, which decreased the splitting fracture performance. The tool back surface wear width of 0.066%S steel decreased by 21.0% for 0.032% S steel. The roughness of 0.066%S steel decreased by 10.4% for 0.032%S steel. More and longer MnS inclusions broke the continuity of the matrix and improved the machining performance. For connecting rod manufacturing, to ensure the splitting fracture performance and enhance the machining performance, the sulfur content should be increased. [ABSTRACT FROM AUTHOR]

Gadolinium-substituted cobalt manganese ferrite nanoparticles with the composition Co 0.6 Mn 0.4 Gd x Fe 2- x O 4 (where x ranges from 0.0 to 0.08, with x = 0.02) were prepared through the sonochemical method. X-ray diffraction reveals that grown samples are single-phase cubic spinel belonging to space group Fd 3 m, where the crystallite sizes decrease with increasing Gd3+ content. At high doping ratios (x > 0.06), there was a slight increase in crystallite size compared to that of pure Co–Mn ferrite (x = 0), while the lattice parameter (a) decreased in the low doping range of Gd (x < 0.06), resulting in a reduction in crystallite size. Bertaut's method confirms that 80 % of the tetrahedral (A) sites were occupied by Mn ions, while the remaining sites were occupied by other cations in the octahedral (B) positions. Gd3+ ions were found exclusively in the octahedral-B sites. Co2+ ions were expected to occupy the octahedral-B site, which was confirmed in this study for the x = 0.0 and 0.02 samples. Field emission scanning electron microscopy shows the samples are agglomerated and have dense structures. Fourier transform infrared and Raman spectra validated the presence of spinel ferrite modes. Dielectric investigations indicate that as the Gd3+ content exceeds x = 0.0, the dielectric constant and dielectric loss decrease at lower frequencies. The observed dielectric behavior exhibited typical dispersion patterns attributed to Maxwell-Wagner polarization. Furthermore, changes in dielectric properties were observed as the Gd3+ content in Co 0.6 Mn 0.4 Gd x Fe 2- x O 4 nanoparticles increased, which can be attributed to the presence of oxygen vacancies and variations in the distribution of Fe3+ ions at both A and B-sites. [ABSTRACT FROM AUTHOR]

In order to improve the microwave-absorption performance of barium ferrite and broaden its microwave-absorption band, BaFe12O19, Ba0.95Ca0.05Fe12O19, and Ba0.95Ca0.05Fe12−xCoxO19 (x = 0.1, 0.2, 0.3 and 0.4, respectively) hexaferrites were synthesized by the solid-state reaction method, and the influence of Co ion substitution on the phase composition, microstructure, magnetic properties, and microwave-absorption ability of the ferrites in this system was studied. Introducing minor Co ions (x < 0.2) facilitated sintering and grain growth. At x ≥ 0.2, XRD revealed the emergence of the Co2X phase alongside the BaM phase. Increasing Co ion concentration and the secondary X-phase led to slight reductions in saturation magnetization (69 to 63.5 emu/g) and substantial decline in coercivity (2107.02 to 111.21 Oe), attributed to grain size growth and Co2X's soft magnetic nature. Notably, Co2X incorporation significantly enhanced the microwave absorption and provided a tunable absorption band from the Ku to the C band. For a sample with a thickness of 2.0 mm and a doping level of x = 0.2, a minimum reflection loss of −59.5 dB was achieved at 8.92 GHz, with an effective absorption bandwidth of 3.31 GHz (7.07–10.38 GHz). The simple preparation method and good performance make Ba0.95Ca0.05Fe12−xCoxO19 (x = 0.1, 0.2, 0.3 and 0.4, respectively) hexaferrites promising microwave-absorbing materials. [ABSTRACT FROM AUTHOR]

This study reports new observations from the fabrication of high-aspect-ratio hollow tubes of SS410 through wire-arc directed energy deposition (wire-arc DED) process. Characterisation work was performed on a single tube as a function of its build height. The maximum ultimate tensile strength (UTS) of 1372 MPa and maximum yield strength (YS) of 980 MPa were achieved in the middle region of the tube. The highest UTS in the middle was attributed to the low delta ferrite content. The reduction of delta ferrite was found to be linked with the repetitive heating and cooling. In contrast, the top and bottom sections exhibit a substantial presence of delta ferrite, indicating that the cyclic effects were not considerable. Nevertheless, the presence of significant ductility in the bottom region of the component indicated the occurrence of tempering effects. This observation is further supported by the lower levels of local strain observed using KAM mapping. Overall, this work proposes a novel fabrication method for producing hollow sections with superior strength and ductile properties. [ABSTRACT FROM AUTHOR]

MnZn ferrite powders were prepared, based on the novel nano-in-situ composite method and through chemical sol–spray–calcination technology. Different dosage of CTAB were used, and the influences on the precursor sol solutions and precursor powders were studied. Also, the selected precursor powders (P-0.1CTAB) were calcined at 1060 °C in air for 3 h, and the sample (S-0.1CTAB) was considered to further exploration. The results indicated that the precursor sol and precursor powders were in their optimal state when adding 0.1 wt.% CTAB. Under this condition, the Zeta potential of the sol was 10.7 mV, and the colloidal particle size was 91.63 nm. The corresponding precursor powders can still maintain a nanoscale fine particle composition and be well dispersed. The S-0.1CTAB sample with hollow spherical shell composed of small particles of several hundred nanometers had pure MnZn ferrite phase, and the maximum value of saturation magnetization (Ms) was 53.46 emu/g. Moreover, there are three stages of the formation of MnZn ferrite during the CTAB-assisted synthesis process which are CTAB ionization and (Mn, Zn, Fe)(OH)(NO3)(H2O) formation stage, CTA + adsorption and colloidal particle formation stage, and (Mn, Zn, Fe)(OH)(NO3)(H2O) decomposition stage. [ABSTRACT FROM AUTHOR]

To fulfill the urgent demand for materials suitable for contemporary high-frequency applications, Eu-substituted Ni 0.55 Zn 0.35 Co 0.1 Eu x Fe 2- x O 4 (NZCEF, 0 ≤ x ≤ 0.10) composite ferrites were successfully synthesized by a solid-state reaction method, demonstrating characteristics apt for high-frequency functionalities. Detailed examination via SEM and EDS confirmed the compositional purity of these ferrites. Microstructural analysis indicates that the incorporation of europium results in a reduction of the average grain size in NZCEF composites, enhancing the material's densification. Measurements of resistivity and dielectric properties reveal that Eu doping affects the concentration of Fe2+ and Fe3+ ions as well as lattice defects within the ferrite, thereby leading to higher dielectric constants and resistivity (ρ , 6.51 × 108 Ω m). Magnetic analysis confirms that the substitution with Eu ions significantly increases both the coercivity and the ferromagnetic resonance frequency (f r), from 25.7 Oe and 445 MHz to 45.73 Oe and 1.22 GHz, respectively. This improvement is attributed to changes in grain size and domain wall motion. Consequently, Eu3+-substituted NZCEF ferrites exhibit superior electromagnetic properties, making them ideal candidates for advanced high-frequency material applications. [ABSTRACT FROM AUTHOR]

The global water resource shortage has evolved into a pressing concern, necessitating the advancement of effective and environmentally sustainable water treatment techniques. Photocatalysis has surfaced as a hopeful technology for eliminating organic contaminants from wastewater because of its efficiency, cost-effectiveness, and eco-friendliness. Here, CeO 2 microspheres and Ni 0.5 Zn 0.5 Fe 2 O 4 (NiZn-ferrite) nanoparticles were synthesized using the hydrothermal method, followed by the fabrication of ternary hybrid composites CeO 2 /NiZn ferrite/multiwalled carbon nanotubes (MWCNT) via ultrasonic treatment. Various analytical techniques including XRD, FESEM, VSM, PL, BET and UV–Visible spectroscopy were employed to characterize the resulting synthesized samples. The hybrid ternary composites demonstrate remarkable efficiency in degradation of reactive red-35 dye through photocatalysis attributed to enhanced surface area. This efficiency is further enhanced when coupled with ultrasonic treatment, leading to a synergistic effect. The catalysts can be easily separated from the suspension due to their magnetic behaviour and thus hold great potential for utilizations in the field of wastewater treatment and environmental remediation. [ABSTRACT FROM AUTHOR]

LiZnTi ferrites with dense microstructure and excellent gyromagnetic properties are a critical class of materials for microwave ferrite devices. Many reported studies have demonstrated that grain refinement and good gyromagnetic properties is often contradictory. In this work, we have successfully prepared a highly-dense LiZnTi ferrite with small average grain size (<1.0μm) and good gyromagnetic properties by hot-pressure sintering (HPS) method. Interestingly, SEM images revealed that the hot-pressure sintering with zero holding time not only promoted densification of the LiZnTi ferrites, but also can realize their grain refinement, which effectively reduced porosity and improved gyromagnetic properties. Meanwhile, we found that the average grains size (GS ave.) of the HPS950 sample is smaller than the TS950 and HPS900 samples due to the synergistic effect of applied pressure (zero holding time) and Bi 2 O 3 liquid phase. Finally, a LiZnTi ferrite with uniform, dense grains (GS ave. = 0.85 μm and ρ r = 98.1 %) and good gyromagnetic properties (4π M s = 3859.6Gs and ΔH = 287.4 Oe) was obtained by hot-pressure sintering at ∼950 °C. [ABSTRACT FROM AUTHOR]

MnZn ferrite powders were prepared based on the novel nano in situ composite method and through chemical sol-spray drying–calcination technology. The precursor powders were calcined at 1060 °C at different calcination times (1–9 h) to research the influences of the calcination time on MnZn ferrite powders. The research results revealed that all samples had similar morphologies composed of fine particles. The pure MnZn ferrite spinel phase can only be obtained when the calcination time does not exceed 3 h. Otherwise, some α-Fe2O3 or γ-Fe2O3 impurities will appear. The particle size descended with an increasing calcination time and then ascended. After 3 h of preservation, the smallest particle size was obtained, and it exhibited a unimodal distribution. The saturation magnetization (Ms) increased at first and decreased later with an increasing calcination time, and the optimal value (53.4 emu/g) was reached after holding for 3 h. In view of this work, the optimal calcination time is 3 h. [ABSTRACT FROM AUTHOR]

The non‐reciprocity of electromagnetic waves is a technology garnering significant attention for its applications in electromagnetic security and the mitigation of electromagnetic interference, serving to control radio waves in space. This article outlines a comprehensive design approach for a novel non‐reciprocal structure that integrates ferrite and metal patches. Additionally, it presents experimental results utilizing two types of ferrites. The experiments demonstrated the attainment of 15 dB isolation at both 6.25 GHz and 6.5 GHz. [ABSTRACT FROM AUTHOR]

Abstract Traditional soft ferrite manufacturing is limited to simple geometries and materials, while 3D printing offers greater flexibility for complex designs. Notably, soft ferrites are crucial for magnetic couplers (pads) in inductive power transfer (IPT) systems to achieve efficient wireless power transmission. The adoption of soft ferrite 3D printing in IPT systems could lead to significantly improved magnetic coupler design, yet research in this area is limited. Hence, the paper first makes a comprehensive comparison of the existing soft ferrite 3D printing methods to ascertain their suitability for magnetic couplers in IPT systems, and then proposes the binder jetting (BJT) as a potential 3D printing approach that could be appropriate for IPT magnetic coupler implementation being versatile, cost‐effective, and suitable for large‐scale manufacturing with high precision. This paper explores the suitability of BJT by 3D printing toroid cores with Mn–Zn ferrite powder under different sintering temperature profiles. Experimental results are presented to show that toroid cores can be 3D printed with high printing precision, mechanical strength, and a relative permeability of 10. This paper also highlights the impact of sintering temperature on 3D‐printed cores, the challenges, limitations, and future research directions of soft ferrite 3D printing for IPT magnetic couplers by the BJT method.

In this study, a novel NiCuZn (Ni 0.24 Cu 0.21 Zn 0.55 Bi x Fe 2- x O 4 (x = 0,0.025, 0.050, 0.075)) ferrite composition (Ni/Zn molar ratio is 24/55) was successfully prepared by the addition of Bi3+ ion for substitution. It is demonstrated that Bi 2 O 3 served as an effective doping agent to reduce the sintering temperature to 900 °C and enhanced the high-frequency magneto-dielectric properties. Notably, the maximum permeability is ∼118 (@ 13.56 MHz) when x = 0.050 with a cut-off frequency of 47 MHz, which is nearly four times higher than that of the unsubstituted sample. In addition, an NFC antenna employing optimized ferrite as an electromagnetic shield sheet was designed and simulated. The results indicated that the chaotic and weakened magnetic field was recovered, and the biased resonant frequency was restored from 31.87 MHz to 13.68 MHz. These findings hold significant scientific importance and practical value in achieving superior electromagnetic shielding performance and miniaturization in NFC system. [Display omitted] [ABSTRACT FROM AUTHOR]

With the miniaturization and integration of electronic components, there has been widespread attention on yttrium iron garnet ferrite (YIG) with high saturation magnetization, high dielectric constant, and low ferromagnetic resonance linewidth. In this work, In–Sn–Cu co-doped YIG ferrite with the chemical formula Y 3 Fe 4.8-x Cu 0.1 Sn 0.1 In x O 12 (x = 0.05, 0.10, 0.20, 0.30) was prepared. The properties of the samples, including their microstructure, crystal structure, magnetic attributes, and dielectric properties, were adjusted through the regulation of the indium doping levels. The microscopic and crystal structures confirm the effective doping of ions in YIG, resulting in an expansion of the lattice parameters. Both the saturation magnetization ( M s) and the ferromagnetic resonance linewidth (Δ H ) are influenced by the level of doping. The maximum value of M s is observed at x = 0.10 (30.86 emu/g), whereas the minimum value of Δ H occurs at x = 0.20 (35 Oe). Additionally, increasing doping concentration also leads to an upward trend in both resistivity and dielectric constant, with the lowest dielectric loss occurring at x = 0.15. This study will provide an effective approach for developing high-performance YIG ferrite that meets the requirements of miniaturization and integration. [ABSTRACT FROM AUTHOR]

Magnetic field-assisted method has been proved as an effective method to improve oxygen evolution reaction performance (OER) of water splitting, however, the essential reason for the improvement of OER performance still remains unclear. Herein, Ni 1- x Zn x Fe 2 O 4 ferrites were prepared by the combination of hydrothermal and calcination method, the magnetic properties, oxygen evolution reaction performance and the effect of applied magnetic field on OER performance were studied and discussed according to the magnetic properties and ion site situation. The magnetic field effect depended on the applied magnetic field strength and the magnetic magnetization density of catalysts, it was attributed to changes of electron state and redistribution of ions in the spinel structure. The overpotential decreased by approximately 50 mV and its double layer capacitance increased about 60 % at 125 mT applied magnetic field. The results provided a newness research view for the domain of electrochemistry. [ABSTRACT FROM AUTHOR]

The aim of this study is to investigate the structural, magnetic, and blood compatibility properties of Sr2+ substituted for Cu2+ in Cu 1−x Sr x Fe 2 O 4 (x = 0.0 to 1 with a 0.25 increment) nanoparticles synthesized via the sol-gel auto-combustion technique. Regardless of the substitution rate, the sol-gel auto-combustion method consistently yields powders with sizes ranging from 20 to 40 nm. The specific surface area of the produced powders is determined as 12 m2/g. X-ray diffraction analysis reveals that CuFe 2 O 4 exhibits a singular phase; however, as the Sr2+ ion substitution increases, the emergence of various secondary phases becomes apparent, with their proportions increasing with the substitution rate. The magnetic characteristics of the synthesized powders exhibit variations in magnetization, correlating with the distribution of cations in the sublattice points. Coercivities are influenced by both anisotropy and secondary phases. Saturation magnetization decreases from 31.3 (CuFe 2 O 4) to 7.6 (SrFe 2 O 4) emu/g with Sr replacement. The lowest observed coercivity is 429.5 Oe in powders prepared with CuFe 2 O 4 composition, while the highest is measured at 583.8 Oe in nanopowders prepared with Cu 0.5 Sr 0.5 Fe 2 O 4 composition. Moreover, blood compatibility experiments indicate significantly low hemolysis ratios for Cu 1−x Sr x Fe 2 O 4 nanoparticles. Additionally, all examined samples exhibit an increase in Soret band intensity compared to the negative control test, suggesting potential biocompatibility. [ABSTRACT FROM AUTHOR]

Crystal structure, microstructure, static and dynamic magnetic properties of Ba 3-x Nd x Co 2 Fe 24 O 41 (x = 0.0, 0.1, 0.2, 0.3, 0.4, and 0.5) ceramics were investigated. Samples were prepared via sintering at 1250 °C for 4 h, and XRD results revealed their crystal structure after Nd substitution. With the increase in Nd3+ ion dopant content, particle porosity increased, leading to slight decrease in volume density. Static magnetic data showed the weak effect of Nd-substitution on saturation magnetization strength and a slight increase in coercivity (from 52 Oe to 75 Oe at x = 0–0.5), while out-of-plane magnetic anisotropy rose significantly (from 10.1 kOe to 14.5 kOe at x = 0–0.5). Dynamic magnetic tests demonstrated noticeable decrease in permeability (from 17 to 8), whereas cutoff frequency increased from 0.8 GHz to 1.9 GHz and the maximum Snoek product reached 18.8 GHz for the sample with x = 0.4. The fitting of real part of permeability using domain wall resonance and natural resonance models revealed that resonance frequency and out-of-plane anisotropy both increased with Nd-substitution. Moreover, despite Nd doping, samples maintained low magnetic loss and high Q value within higher frequency range. Therefore, findings of this study provide a pathway to development of substituted Z-type barium (Co 2 Z) ferrites for high frequency applications. [Display omitted] [ABSTRACT FROM AUTHOR]

To expand the effective microwave absorption efficiency of barium hexa-ferrite (BaM)/polyaniline (PANI) composites, a technique based on lanthanum (La) doping and surface carboxylation of BaM nano powders is explored to simulate the interfacial polarization between BaM and PANI. La doping of BaM nano powders not only regulates the magnetic properties and microwave response of ferrite itself, it also activates the surfaces of ferrite particles for the deposition polymerization of PANI. Surface carboxylation provides activated sites for PANI on the surfaces of ferrite particles, leading to formation of rod-like PANI. All these together make contributions to enriched reflection loss modes, resulting in the fine microwave absorption properties. With La-doping in BaM is 5 mol% (x = 0.05) and surface carboxylation has been performed, the microwave absorption properties of the synthesized composites were characterized of a high efficiency of − 51 dB and the effective absorption bandwidth of 2.8 GHz at a thickness of 5 mm. This provides an effective method to improve the microwave absorption performance of the conventional absorption medium, barium ferrite. [ABSTRACT FROM AUTHOR]

A series of chromium-substituted cadmium post-spinel ferrites CdCr x Fe 2-x O 4 (x = 0.0, 0.1, 0.3, 0.5) have been synthesized through the sol-gel auto-ignition method. The structural, vibrational, dielectric, magnetic, and microwave absorption properties of β -spinel ferrites through modern techniques which include X-ray diffraction, FTIR Spectroscopy, and Vector network analyzer. X-ray diffraction technique was used for structural investigation which confirmed the monophasic orthorhombic structure of prepared samples and a detailed study revealed that no impurity/additional phases were detected. Crystallite size and strain were extracted via the Williamson-Hall (W–H) method and Size strain plot (SSP). Vibrational spectroscopy (FTIR) successfully verified the spectral qualities of studied ferrites as measured wave number ranges between 400 and 600 cm−1. X-ray photoelectron spectroscopy verified that all metal ions exist and possess the corresponding electronic states. Electrical properties have been investigated at the microwave region (1 MHz – 6 GHz). The conduction mechanism has been studied via Johnscher power law. The Cole-Cole plot of all the samples consisting of two semicircles corresponding to grain and grain boundaries described the increasing conduction phenomena. In the present research, stable dielectric constant, dielectric loss, enhanced magnetic characteristics, and minimum reflection loss (−31.9 dB) make these CdCr x Fe 2-x O 4 nano-crystallites most suitable candidates for highly dense and high-frequency microwave devices for EMI shielding material. [ABSTRACT FROM AUTHOR]

In this paper, the microstructure and mechanical properties of a new type of low Ni duplex stainless steel after resistance spot welding were studied. The welding current has a great influence on the welding performance of resistance spot welding, so it is necessary to clarify the influence law and mechanism of welding current on the welding performance of low Ni duplex stainless steel. The microstructure of the samples under different welding currents was analyzed in detail by EBSD, and the mechanical properties of the treated samples were measured. The results show that the volume fraction of austenite in nugget zone is affected by changing welding current. This is because the higher cooling rate of resistance spot welding inhibits the phase transformation of ferrite to austenite and reduces the volume fraction of austenite, resulting in the imbalance of ferrite and austenite phases. When the welding current is the largest, the cooling rate is the lowest, which corresponds to the highest austenite volume fraction. [ABSTRACT FROM AUTHOR]

In this work, Co0.5Zn0.5LaxFe2-xO4 (0.00 ≤ x ≤ 0.10) spinel ferrites were synthesized using the sol-gel auto-combustion method. X-ray diffraction (XRD) analysis and Rietveld refinement confirmed the presence of a cubic spinel structure. The crystallite size was estimated to be between 17.5 nm and 26.5 nm using Scherrer's method and 31.27 nm-54.52 nm using the Williamson-Hall (W-H) method. Lattice constants determined from XRD and Rietveld refinement ranged from (8.440 to 8.433 Å and 8.442 to 8.431 Å), respectively. Scanning electron microscopy (SEM) revealed a non-uniform distribution of morphology with a decrease in particle size. The bandgap values decreased from 2.0 eV to 1.68 eV with increasing rare earth (La3+) doping concentration. Fourier-transform infrared (FT-IR) spectroscopy confirmed the presence of functional groups and M-O vibrations. The dielectric constant and dielectric loss exhibited similar behavior across all samples. The maximum tan d value obtained at lower frequencies. Regarding magnetic behavior, there was a decrease in magnetization from 55.84 emu/g to 22.08 emu/g and an increase in coercivity from 25.63 Oe to 33.88 Oe with higher doping concentrations. Based on these results, these materials exhibit promising properties for applications in microwave and energy storage devices. [ABSTRACT FROM AUTHOR]

The development of multi-functional and highly mixed ionic-electronic conductive perovskite oxide-based electrodes is becoming an established trend for designing and developing SOFC/SOEC reversible cells. Ideally, the same material can be employed at both electrodes provided that structural stability, high conductivity and catalytic activity are preserved in different operational atmospheres. Here, controlled Fe substitution with a small extent (0.5 mol%) of platinum at the B-site of a lanthanum strontium ferrite is proposed as an effective method to enhance the original oxide properties as both air and fuel electrode for solid oxide cells. The effects of low Pt-doping on La 0.6 Sr 0.4 FeO 3-δ structure, morphology and electrocatalytic activity are investigated and discussed. La 0.6 Sr 0.4 Fe 0.995 Pt 0.005 O 3-δ (05P-LSF) is first tested as air electrode, displaying lower area specific resistance as compared to the Pt-free perovskite. 05P-LSF structural stability and conductivity are assessed in 100 % CO 2 and 50 % CO 2 –50 % CO environments. Symmetric devices are then tested as SOECs in 100 % CO 2 , obtaining a current density output of 1.08 A/cm2 at 1.5 V. Electrochemical impedance spectroscopy (EIS) with distribution of relaxation times analysis (DRT) are used to provide insights on the electrode operation. Pt nanoparticle exsolution at the fuel electrode is induced by voltage application. The device stability under applied voltage is assessed for over 120 h. SOFC/SOEC characterization in a 50 % CO 2 /50 % CO mixture at 850 °C is also provided, obtaining a maximum power density of 270 mW/cm2 in SOFC mode, and a current density of 0.91 A/cm2 at 1.5 V in SOEC mode. [ABSTRACT FROM AUTHOR]

The high-temperature oxidation behavior of Cr-Mn-Si alloyed steel by Fe 2 O 3 contained mold flux in high temperatures, and its effect on microstructure evolution were investigated in detail by TEM, EBSD, CLSM, SEM, and XPS. A novel oxidation mechanism was firstly revealed that the Fe 2 O 3 in mold flux melts during high temperatures plays a role of oxidizing alloyed steels by the released free oxygen ions (O2−) from the transformation of Fe 2 O 3 (Fe3+) to FeO (Fe2+). The formed oxidized dots within the oxide layer changed from SiO 2 and MnSiO 3 to MnCr 2 O 4 spinel phases by increasing the content of Fe 2 O 3 in the mold flux. Notably, the amorphous SiO 2 was discovered in the core region of MnSiO 3 phase due to its selective oxidative behavior in high temperatures. This research provides conclusive evidence that the small size MnSiO 3 oxides can be acted as a nucleation core for the refinement of austenite grains through in-situ observation. [ABSTRACT FROM AUTHOR]

Nanocrystalline cobalt ferrites co-substituted with rare earth Ho and Er (CoFe 2-2 x Ho x Er x O 4 , 0 ≤ x ≤ 0.10) have been synthesized via the sol-gel method. X-ray Diffraction (XRD) confirmed the single-phase spinel structure with reduced crystallite sizes (65 nm–12 nm), micro-strain (ε) and increased lattice constant (a) with Ho–Er co-substitution. Rietveld refinement and theoretical computation revealed Ho and Er occupancy at octahedral sites and Fe and Co ions redistribution between the tetrahedral and octahedral sites. Infrared spectroscopy, Field Emission Scanning Electron Microscopy (FESEM), Energy Dispersive X-ray spectroscopy (EDX) and X-ray Photoelectron Spectroscopy (XPS) supported the formation of the desired spinel structure, aggregated spherical morphology, chemical stoichiometry and elemental states. Magnetic measurements showed a systematic decrease in saturation magnetization (M s), magnetocrystalline anisotropy (K 1), coercivity (H c) and Curie temperature (T c) with Ho–Er co-substitution. Electron Spin Resonance (ESR) exhibited asymmetric resonance peaks, reduced resonance field (H r), linewidth (ΔH pp) and deviation in Lande g values. Impedance spectroscopy revealed two conduction mechanisms (holes and electrons) with distinct activation energies (E aI and E aII). Modulus spectrum analysis confirmed the thermally activated sample-electrode effects and the Nyquist plots indicated the dominant contribution of the grain boundary resistance to the conduction process. A notable enhancement in the dielectric constant (ε′) was observed with Ho–Er co-substitution. The ac conductivity (σ ac) followed the Jonscher Power Law (JPL). The temperature-dependent frequency exponent s(T) , suggests the existence of two conduction mechanisms: non-overlapping small polaron tunneling (NSPT) and correlated barrier hopping (CBH). [ABSTRACT FROM AUTHOR]

This study extensively investigates Ni 0.4 Cu 0.2 Zn 0.4 Fe 2-4x Sn 3x O 4 (x ≤ 0.10) nanospinel ferrites, denoted as NCZFe 2-4x Sn 3x O 4 NSFs, focusing on their structural, morphological, electrical, and dielectric characteristics. Utilizing various techniques such as SEM, EDX, TEM, XRD, and impedance analysis, the research confirms the cubic spinel structure and composition of the nanoferrites. The substitution of Sn 4+ ions into Ni 0.4 Cu 0.2 Zn 0.4 Fe 2 O 4 NSFs is explored, with a thorough examination of dielectric and electrical parameters up to 1.0 MHz and temperatures ranging from 20 to 180 °C. Complex impedance spectroscopy is employed to represent these parameters in a logarithmic 3D graph, revealing insights into ac/dc conductivity, activation energies, dissipation factor, dielectric constant, and loss. The study observes adherence to the power-law frequency rule in ac conductivity and highlights the impact of temperature and substitution ratios on grains, grain boundaries, and elemental composition. The investigation suggests a conduction mechanism involving electron and polaron hopping , and ionic contributions. Dielectric parameters show frequency-dependent changes that relate the dielectric constant to space charge polarization, inhomogeneous dielectric structure, impurities, and grains /grain boundaries. Cole-Cole impedance plots display semicircles dependent on substitution ratios and temperature, emphasizing contributions from grains, grain boundaries, and ionic mobilities. The Nyquist plots of Cole-Cole impedance functions further underscore substantial complexity in the conduction mechanism of the substituted NCZFe 2-4x Sn 3x O 4 NSFs. [ABSTRACT FROM AUTHOR]

As a part of last-mile transportation, electric three-wheelers, popularly known as trikes, are considered as an important aspect of the future of the auto industry. The appropriate choice of electric traction motor drive is imperative to the design of an electric motor power train. In this paper, six main types of sinusoidal-fed electric motor power trains--Ferrite-Assisted Synchronous Reluctance Motor (FASRM), Synchronous Reluctance Motor (SyncRelM), Ferrite-based Spoke motor, Ferrite-based Surface-Mounted Permanent Magnet Synchronous Motor (SMPMSM), Wound-Field Synchronous Motor (WFSM), and Induction Motor (IM)--are compared for their performance in electric trike applications. The permanent magnet machines presented here utilize ferrite magnets, in line with the recent trend of not using rare-earth magnets. The comprehensive comparative analysis establishes that SyncRelM, FASRM, and Spoke motors are superior in terms of overall electromagnetic, thermal, and vibration performance. This paper also focuses on an optimal design of the FASRM due to its high torque density, lower torque ripple, and minimal use of ferrite magnets. A Design of Experiments (DoE)-based statistical analysis tool is used to identify the key parameters needed for robust motor performance in the optimization step. Furthermore, an Extreme Learning Machine (ELM)-based interpolation technique is employed for estimating the performance parameters during each step of the optimization routine. A 1.2 kW FASR motor prototype is developed and tested. A comparison of Finite-Element-Analysis-based modeling results is presented along with Indian drive-cycle results for the FASRM for trike application. [ABSTRACT FROM AUTHOR]

In this study, an effort was made to compare the impact of diverse organic fuels on structural and magnetic properties of the pure rubidium ferrites. A novel solution‐based combustion method was proposed that offered simplicity, cost effectiveness, and scalability. Pure rubidium ferrite (RbFeO2) was prepared by using diverse organic fuels such as urea, ethylene glycol (EG), and oxalyl dihydrazide (ODH) to facilitate exothermic reaction for homogeneous product. It was then characterized by different physico‐chemical techniques like X‐ray diffraction (XRD), transmission electron spectroscopy (TEM), Mössbauer spectroscopy, and vibrating sample magnetometer (VSM). Findings revealed that the choice of fuel significantly influenced the particle size and magnetic properties of the product. X‐ray diffraction patterns showed the formation of homogeneous nano‐powder confirmed by TEM analysis. TEM image analysis revealed that the average particle size of the final product obtained was 18 nm for EG, 80 nm for urea, and 40 nm for ODH, respectively. Saturation magnetization values were comparable to lithium ferrites reported in the literature. Mössbauer studies indicated that sample prepared by using EG has better magnetic properties for the application as soft magnetic devices. [ABSTRACT FROM AUTHOR]

To meet the challenge of varied working temperatures of inductance components in new energy vehicle and 5G communication, the high- T C high-permeability MnZn ferrite with excellent temperature stability was developed by the addition of SnO 2. In this series of samples, initial permeability μ i maintains large values in a wide temperature range. With increasing the SnO 2 content, the temperature of the second permeability peak T sp decreases and meanwhile Curie temperature T C maintains as high as 160 °C. For the best sample with 6000 ppm SnO 2 , μ i at 25 °C is 7244 and exhibits the excellent temperature stability with the low specific temperature coefficient of 0.35 × 10−6 °C−1 between 25 and 130 °C. The addition of SnO 2 generates Fe2+ and adjusts the magneto-crystalline anisotropy constant K 1 = 0 point, which is responsible for the wide-temperature high permeability. The effect of SnO 2 addition on magnetization process has also been clarified. [ABSTRACT FROM AUTHOR]

The permeability of the Fe Soft Magnetic Composite (SMC) materials need further improve to broaden their application prospect. This research work presents a novel high permeability SMC material which has a low core loss (P cv). The Fe particles formed an elongated strip shape structure through the ball milling process, and the high permeability Mn 0.5 Zn 0.5 Fe 2 O 4 ferrite phase was formed around the elongated strip shape Fe particles via a high temperature in-situ reaction process (ZnO + MnO + Fe 2 O 3 –Mn 0.5 Zn 0.5 Fe 2 O 4). While the added high resistive SiO 2 phase aggregated at the long strip shape Fe particle outer surface and effectively increased the resistivity of the SMCs. As the percentage of the Mn 0.5 Zn 0.5 Fe 2 O 4 ferrite coating increase, the permeability of the double layer coated SMCs gradually increased from 38 for the 1 wt% Mn 0.5 Zn 0.5 Fe 2 O 4 coated SMCs to 170 for the 18 wt% Mn 0.5 Zn 0.5 Fe 2 O 4 coated SMCs. The 3 wt% Mn 0.5 Zn 0.5 Fe 2 O 4 coated SMCs has the lowest core loss (P cv) of 86.9 W/kg at 10 mT, 500 kHz. [ABSTRACT FROM AUTHOR]

A hydroelectric cell has been coined as an accomplished device keeping the ability to produce current just by adsorbing a few microliters of water. These cells are the new source of generating green energy which involves no evolution of toxic gases like NO2, SO2, CO, etc. Our current research focuses on studying how to increase the maximum output current (I) in the pure cobalt ferrites by doping with rare-earth ion, yttrium. The yttrium-doped cobalt ferrites with composition (CoYxFe2−xO4, x = 0.00, 0.10, and 0.20) have been prepared using a modified sol–gel citrate method. X-ray diffractogram (XRD) confirmed the formation of cubic crystal structures with crystallite size less than 30 nm. Energy dispersive x-ray (EDX) patterns confirmed the presence of elements (Y, Co, Fe, O) in the prepared compositions. The ionic diffusion mechanism confirmed the dissociation of water molecules by the cations present on the surface of the material at room temperature. Vibrating sample magnetometer (VSM) analysis revealed the increase in coercivity values from 948.81 Oe to 2580.09 Oe with the increase in the concentration of yttrium ions in the cobalt ferrite (CFO) lattice. The V–I polarization curves measured the maximum output current and voltage as around 8.6 mA and 1.1 V, respectively, for the 20% yttrium-doped CFO hydroelectric cells (area = 4 cm2). [ABSTRACT FROM AUTHOR]

Magnesium-doped nickel ferrite nanoparticles with the chemical composition (Ni1−xMgxFe2O4, x = 0.00, 0.20, and 0.40) have been prepared by a modified sol–gel citrate method. Structural analysis was carried out through x-ray diffractograms (XRD) and Fourier-transform infrared (FTIR) spectroscopy. The spherical-shaped morphology of the prepared nanoparticles has been confirmed by field-emission scanning electron microscopy (FESEM). The energy dispersive x-ray (EDX) analysis confirmed the presence of elements (Ni, Mg, Fe, and O) in the prepared compositions. The distribution of cations over tetrahedral and octahedral sites has been confirmed by Rietveld refinement using FullProf software. The phenomena of Maxwell–Wagner polarization is exhibited in the dielectric measurements. Cole–Cole plots showed that the net grain (Rg) and grain boundary resistance (Rgb) values are decreasing for the maximum concentration of Mg2+ ions in the nickel ferrites. Almost 96% deductions in the tangent loss values have been observed at high temperatures with the increasing concentration of Mg2+ ions in the nickel ferrites. Fitting of AC conductivity was carried out using the Jonscher Power Law function. The net magnetization saturation values also decreased from 27.7 emu/g to 16.7 emu/g upon the doping of Mg2+ ions in the pure nickel ferrites. These properties are all desired for materials working under high-frequency applications. [ABSTRACT FROM AUTHOR]

The damage to the shear-punched surface layers such as strain-hardening, strain-induced martensite transformation, and micro-void initiation behaviors was evaluated in the third-generation low-carbon advanced ultrahigh-strength TRIP-aided bainitic ferrite (TBF), bainitic ferrite–martensite (TBM), and martensite (TM) steels. In addition, the surface layer damage was related to (1) the mean normal stress generated during shear-punching and (2) microstructural properties such as the matrix structure, retained austenite characteristics, and second-phase properties. The shear-punched surface layer damage was produced under the mean normal stress between zero and negative in all the steels. The TBM and TM steels achieved relatively small surface layer damage. The small surface layer damage resulted in excellent cold stretch-flangeability, with a high crack-propagation/void-connection resistance on hole expansion. [ABSTRACT FROM AUTHOR]

ZnFe2O4 nanomaterials were synthesized using the sol-gel method with different fuels: citric acid, tartaric acid, ascorbic acid and glucose monohydrate. The effects of organic fuel type and calcination temperature on the magnetic properties of zinc ferrite were studied. X-ray diffraction analysis, thermogravimetric analysis, differential scanning calorimetry, and transmission electron microscopy were used to investigate the process of zinc ferrite formation during the calcination of intermediate gel products, as well as to analyze the crystal structure and samples morphology. The formation of hematite and wurtzite secondary phases was confirmed for some materials, and the influence of heat treatment conditions on impurity formation was discussed. The particle size of zinc ferrite was 11–39 nm depending on the calcination temperature and selected fuel. According to data obtained using a vibrating sample magnetometer, the ZnFe2O4 nanoparticles exhibited ferrimagnetic behavior with saturation magnetization values of 1.92–15.61 emu/g. Changing the fuel type and the calcination temperature makes it possible to obtain ZnFe2O4 nanomaterials with specific magnetic properties. Highlight: Nanosized ZnFe2O4 samples were obtained by the sol-gel method using four fuels. The formation of zinc ferrite nanoparticles has been experimentally confirmed The effect of fuel on phase composition of ZnFe2O4 was studied by X-ray diffraction Zinc ferrite nanomaterials exhibit ferrimagnetic behavior at room temperature [ABSTRACT FROM AUTHOR]

In this study, we investigated the effect of grain size of an initial microstructure (pearlite + ferrite) on a resulting microstructure of induction-hardened microalloyed steel 38MnVS6, which is one topical medium carbon vanadium microalloyed non-quenched and tempered steel used in manufacturing crankshafts for high-power engines. The results show that a coarse initial microstructure could contribute to the incomplete transformation of pearlite + ferrite into austenite in reaustenitization transformation by rapid heating, and the undissolved ferrite remains and locates between the neighboring prior austenite grains after the induction-hardening process. As the coarseness level of the initial microstructure increases from 102 μm to 156 μm, the morphology of undissolved ferrite varies as granule, film, semi-network, and network, in sequence. The undissolved ferrite structures have a thickness of 250–500 nm and appear dark under an optical metallographic view field. To achieve better engineering applications, it is not recommended to eliminate the undissolved ferrite by increasing much heating time for samples with coarser initial microstructures. It is better to achieve a fine original microstructure before the induction-hardening process. For example, microalloying addition of vanadium and titanium plays a role of metallurgical grain refinement via intragranular ferrite nucleation on more sites, and the heating temperature and time of the forging process should be strictly controlled to ensure the existence of fine prior austenite grains before subsequent isothermal phase transformation to pearlite + ferrite. [ABSTRACT FROM AUTHOR]

The present work deals with developing a method for revalorizing steel residues to create sunlight-active photocatalysts based on iron oxides. Commercial-grade steel leftovers are oxidized under different combinations of pH and temperature (50–90 °C and 3 ≥ pH ≤ 5) in a low energy-intensive setup. The material with the highest production efficiency (yield > 12%) and magnetic susceptibility (χm = 387 × 10−6 m3/kg) was further explored and modified by diffusion of M2+ (Zn and Co) ions within the structure of the oxide using a hydrothermal method to create ZnFe2O4, CoFe2O4 and combined Co–Zn ferrite. (Co–Zn)Fe2O4 displayed a bandgap of 2.02 eV and can be activated under sunlight irradiation. Electron microscopy studies show that (Co–Zn)Fe2O4 consists of particles with diameters between 400 and 700 nm, homogeneous size, even distribution, and good dispersibility. Application of the developed materials in the sunlight catalysis of black liquors from cellulose extraction resulted in a reduction of the Chemical Oxygen Demand (− 15% on average) and an enhancement in biodegradability (> 0.57 BOD/COD) after 180 min of reaction. Since the presented process employs direct solar light, it opens the possibility to large-scale water treatment and chemical upgrading applications. [ABSTRACT FROM AUTHOR]

In this paper, the solid solution and precipitation behavior of inclusions on the surface and 1/2 thickness of the tested steel plate under the condition of welding heat input of 400 kJ/cm is investigated by using laser confocal experiments with hot-rolled state DH36 ship plate steel as the research object, and the mechanism of the effect of inclusions on the phase transformation of an acicular ferrite is revealed. The results show that the inclusions of the tested steel are mainly composed of Oxide-MnS, MnS, Oxide, TiN, Spinel, etc. The amount of inclusions on the surface of the tested steel plate is significantly higher than that at the 1/2 thickness position. During the heating stage, the small inclusions on the surface immediately disappeared, and the large inclusions gradually solidified in the matrix; atomic diffusion occurred at the bond between the inclusions and the matrix; while the small inclusions at the 1/2 thickness position gradually disappeared at the beginning of the heating stage, and the inclusions began to precipitate and grow when the temperature was increased to 990 °C. The acicular ferrite preferentially nucleates and grows near the boundary of the inclusions during the post-weld cooling stage, and its growth ends when two acicular ferrites cross. [ABSTRACT FROM AUTHOR]

Although spinel ferrite nanostructures with adjustable magnetic properties have long been considered for different applications such as microwave, biomedical and magnetic memory devices, detailed magnetic behavior and structural properties of manganese-cobalt ferrites are yet to be investigated and understood. Here, cobalt ferrite nanoparticles (NPs) substituted with manganese (Co1–x Mnx Fe2O4); 0 ≤ x ≤ 1) are synthesized using a co-precipitation method followed by annealing at 800 °C. X-ray diffraction patterns confirm the formation of cubic spinel structure, which is accompanied with α-‌ Fe 2 O 3 secondary phase when increasing the manganese content of NPs, as also observed using field emission scanning electron microscopy. Hysteresis loop measurements demonstrate an increasing trend of magnetic properties with increasing x, leading to maximum values of saturation magnetization (Ms= 65 emu/g) and coercivity (Hc= 1815 Oe) for Co 0.8 Mn 0.2 Fe 2 O 4 NPs. Meanwhile, first-order reversal curve (FORC) analysis manifests distinct soft and hard magnetic phases induced by the slight enhancement in the manganese content. The magnetic hardening of single domain manganese-cobalt ferrite NPs at room temperature is revealed by an increase in FORC coercivity up to 2480 Oe, being about 90% higher than that for pure cobalt ferrite NPs. Further increasing x weakens magnetic properties, minimizing M s and H c to 10 emu/g and 35 Oe when Mn completely substitutes Co in the spinel ferrite structure. In this case, FORC analysis shows suppressed inter-particle magnetostatic interactions and predominant superparamagnetic contribution for MnFe 2 O 4 NPs. [ABSTRACT FROM AUTHOR]

The sol-gel self-combustion technique was applied to form Cd–Co-based La-doped (Cd 0.5 Co 0.5 La x Fe 2-x O 4) spinel ferrite nanoparticles. A series of six samples was synthesized by varying lanthanum content from x = 0.00 to 0.20. The structural characteristics of the prepared nanoparticles were carried out using X-ray diffraction (XRD) analysis. The (311) plane verified that the prepared nanomaterials are in the spinel phase in all observed XRD patterns. The crystallite size for each sample was determined using the Scherrer formula found in the 8.7–17.8 nm range, which is well correlated with the SSP model. The crystallite size decreased while the lattice constant increased from 8.38 to 8.45 Å with increasing La-content. The increasing trend in the bulk density and X-ray density has been analyzed with the effects of La3+ contents. In Fourier-transform infrared spectroscopy (FTIR), the high-frequency absorption band (υ 1) was found from 522.15 to 541.06 cm−1, whereas the low-frequency band (υ 2) varied from 419.80 to 414.31 cm−1. The surface morphology was carried out by scanning electron microscope (SEM), which positively correlated with XRD analysis. Impedance analyzer (IA) assisted in observing the variations in complex dielectric properties of the compound in the frequency range from 1 MHz to 3 GHz. The dielectric constant and impedance plots depicted that the nano ferrites have good dielectric properties in low-frequency regions due contribution of polarization. While conduction can be made possible in the high-frequency areas as observed through AC conductivity. The electric modulus revealed the relaxation phenomenon at high frequency due to the hopping of electrons at the octa and tetrahedral sites. The magnetic properties were investigated to study the impact of La3+ ion under the applied magnetic field from −15 to 15 kOe. The saturation magnetization, and magnetic remanence were found from 40.6 to 27.7 emu/g and 19.6 to 2.7 emu/g, respectively. The synthesized nanoparticles can be utilized for microwave applications and magnetic storage devices. [ABSTRACT FROM AUTHOR]

Sol-gel auto ignition route was utilized to synthesize a series of Zn-doped Cd–Mg spinel ferrites with composition Cd 0.5-x Mg 0.5 Zn x Fe 2 O 4 (x = 0.0, 0.1, 0.2, and 0.3). All of the prepared nanomaterials that were annealed for 4 h at 900 °C had a cubic structure and were spinel, according to X-ray diffraction studies. The lattice constant decreased as the Zn concentration increased. This is because of the substituent's lower radii. The W–H plot, Size strain plot, and Sherrer Formula were used to calculate the crystallite size, which was in the range of a nanometer. Vibrational spectroscopy studies have also shown that M − O bonds are present in every processed sample and that a spinel cubic structure has formed. Additionally, the cationic distribution and cubic spinel structure were validated by Rietveld refinement of the XRD data. The analysis using X-ray photoelectron spectroscopy (XPS) has confirmed the presence of all metal ions in their respective electronic states. The dielectric characteristics in the 1 MHz-6 GHz range of frequencies were ascertained using an impedance analyzer. Jonscher's power law validated the conduction mechanism in the synthesized ferrite samples. The relaxation time constant calculated from impedance Cole-Cole plots shows that the conduction in all the synthesized nanomaterials was due to the grains rather than the grain boundaries. The minimum reflection loss of −36.54 dB was achieved for Zn-doped Cd–Mg ferrites at x = 0.3. The prepared Zn-doped Cd–Mg spinel ferrites would be an excellent material for high-frequency microwave absorption applications. [ABSTRACT FROM AUTHOR]

Nanoparticles of iron and iron oxides, as well as their composites, are of great scientific and technological interest. However, their properties and sustainability strongly depend on the preparation methods. Here, we present an original approach to synthesizing Fe and FeNix metal nanoparticles by exsolution, in a reducing environment at elevated temperatures from perovskite ferrites (La1−xCaxFeO3−γ, CaFeO2.5, etc.). This approach is made possible by the auxiliary reactions of non-reducible A-site cations (in ABO3 notation) with the constituents of reducing compounds (h-BN etc.). The nanoparticles exsolved by our process are embedded in oxide matrices in individual voids formed in situ. They readily undergo redox cycling at moderate temperatures, while maintaining their localization. Fe nanoparticles can be obtained initially and after redox cycling in the high-temperature γ-form at temperatures below equilibrium. Using their redox properties, a new route to producing hollow and layered oxide magnetic nanoparticles (Fe3O4, Fe3O4/La1−xCaxFeO3−γ), by separating the oxidized exsolved particles, was developed. Our approach provides greater flexibility in controlling exsolution reactions and matrix compositions, with a variety of possible starting compounds and exsolution degrees, from minimal up to ~100% (in some cases). The described strategy is highly important for the development of a wide range of new functional materials. [ABSTRACT FROM AUTHOR]