Aluminum Ferrite Research Articles

Flexible Tribo‐Enhanced Piezoelectric Nanogenerator Based on Aluminium Ferrite Electrospun Hybrid Nanofibers for Energy Harvesting and Patient Rehabilitation Application

AbstractMechanical energy harvesters have recently emerged as promising options for self‐powering sensors and small electronic devices. In this work, aluminum ferrite (AlFeO3)/PVDF hybrid perovskite electrospun nanofiber‐based tribo‐enhanced piezoelectric nanogenerators (TPENGs) are developed for energy harvesting. The as‐fabricated TPENG achieves an average voltage output of 52.3 V and an average current output of 1.23 µA. Additionally, the power density of the TPENG is calculated to be 0.085 W.m−2 at an 80 MΩ external resistance load. A 3D‐printed device is fabricated, containing nylon fabric (tribo‐positive) as a rotor attached to printed fins, while six (AlFeO3)/PVDF hybrid perovskite electrospun nanofiber piezoelectric nanogenerators (PENGs) wrapped with Kapton tape (tribo‐negative) serve as the stator. The three printed fins of the device are moved by a string‐based pulley, generating an open circuit voltage of 200 V and a short circuit current of 4.5 µA. The as‐fabricated 3D‐printed device with TPENGs is used to power small electronics (e.g., LEDs and watch) and an exercise setup, allowing patients to generate power by pulling the attached string, thereby estimating the level of impairment. Integrating energy harvesting into rehabilitation motivates patients to move impaired body parts, enhancing TPENG's application in healthcare as a practical and engaging tool for patient rehabilitation.

Synthetic studies of zinc-doped cadmium aluminum ferrite for the photocatalytic degradation of atrazine

Synthetic studies of zinc-doped cadmium aluminum ferrite for the photocatalytic degradation of atrazine

Characterization of Nano-Structured Magnesium-Aluminum Ferrites Synthesized by Citrate-Gel Auto Combustion Method

An effort is made to find the solution to the new challenges of modification advancements in ferrite technologies. The hypothetical variation in the structural, magnetic, and electrical properties of cubic spinel magnesium aluminum ferrites introduced by the substitution of doping elements has been rationalized and proven. The outcome of aluminum substitution on the magnesium ferrites has been examined and investigated. Spinel ferrites having compositions of MgAlxFe2-xO4 (x = 0.1, 0.2, 0.3, 0.4) were prepared by the sol-gel auto-combustion method. The prepared sample’s characterization, such as scanning electron microscopy (SEM), DC electrical resistivity, AC electrical resistivity, and dielectric properties measurements, were tested using the respective instruments. The grain size and crystal size of all samples were measured from the micrographs of SEM and XRD Data. It is found that the average grain size is within the range of 300 nm - 550 nm for all different series that are formed, keeping the samples at 1100 °C sintering temperatures. A two-probe method experiment with a temperature range of 30 °C to 500 °C gives data on DC electrical resistivity. The Curie temperature depends on the sintering temperature, and it increases with increasing doping concentration. Also, doping influences grain size, which decreases with increasing concentration. Analyzing the SEM micrographs, it is found that the average grain size must decrease in tendency with increasing Al content. DC electrical resistivity exhibits excellent semiconducting behavior. Frequency dependence, dielectric constant, and dielectric loss factors were measured, keeping the frequency range of 75 Hz to 130 MHz at room temperature. The result shows that the dielectric constant (e) and dielectric loss tangent (tan™) decrease with the increase in frequency, while the AC resistivity and Q-factor increase. Comparing the electrical properties of four compositions, it can be suggested that the mixed ferrite, sample-4 (x = 0.3), shows the highest Q-factor of all at 1100 °C.

Hybrid spin Hall nano-oscillators based on ferromagnetic metal/ferrimagnetic insulator heterostructures

Spin-Hall nano-oscillators (SHNOs) are promising spintronic devices to realize current controlled GHz frequency signals in nanoscale devices for neuromorphic computing and creating Ising systems. However, traditional SHNOs devices based on transition metals have high auto-oscillation threshold currents as well as low quality factors and output powers. Here we demonstrate a new type of hybrid SHNO based on a permalloy (Py) ferromagnetic-metal nanowire and low-damping ferrimagnetic insulator, in the form of epitaxial lithium aluminum ferrite (LAFO) thin films. The superior characteristics of such SHNOs are associated with the excitation of larger spin-precession angles and volumes. We further find that the presence of the ferrimagnetic insulator enhances the auto-oscillation amplitude of spin-wave edge modes, consistent with our micromagnetic modeling. This hybrid SHNO expands spintronic applications, including providing new means of coupling multiple SHNOs for neuromorphic computing and advancing magnonics.

Exploring the Decreasing Coercivity Properties of Aluminum Cobalt Ferrites Prepared by Coprecipitation Method

Cobalt aluminum ferrites were synthesized by coprecipitation method at 1000 ºC. XRD studies pointed out the employed samples (Fe2+Al2 3+O42−, Fe0.25Co0.75Al2O4 and Fe0.75Co0.25Al2O4) were crystallized in a single phase cubic spinel form. The synthesized samples were calculated structural parameters such as crystallitesize (D: 17 nm), X-ray density (Dx: 3.97 to 4.15 g/cm3), volume of the unit cell (V: 583.64 to 586.58 Å), lattice strain (ε: 6.9 × 10-3), dislocation density (δ: 3.3 × 10-3) and lattice constant (a: 8.357 to 8.371 Å). The FE-SEM microstructure confirmed that various concentrations result in different particle sizes (5 μm to 500 nm). The magnetic characteristics were investigated by VSM and magnetic parameters like saturation magnetization (Ms: 4.82 × 10-3 to 0.673 emu/g), retentivity (Mr: 1.545 × 10-3 to 0.229 emu/g), coercivity (Hc: 775.45 to 2212.8 Oe), magnetic moment (μB: 1.57 × 10-4 to 2.108 × 10-2), remnant ratio (R: 0.32 to 0.357 no unit) and anisotropy constant (K: 3.418 to 177.57 J/m3) were calculated. High coercivity materials are ideal for use in magnetic recording media, permanent magnets and microwave devices since they possess a high degree of resistance to an external magnetic force.

Effects of synthesized AlFe2O4 and MgFe2O4 nanoparticles on biogas production from anaerobically digested sugar refinery wastewater.

The application of magnetic nanoparticles (MNPs) toward sustainable water economy and bioenergy production has become a subject of great interest. Anaerobic digestion (AD) has been widely exploited in wastewater treatment settings, whereby utilization of MNP additives by microorganism response for degradation of organics into biogas is seen to be eco-friendly and economically viable. The present study investigated the impact of two synthesized MNPs such as aluminum ferrite (AlFe2O4) and magnesium ferrite (MgFe2O4) on biogas production via biochemical methane potential (BMP) tests. A BMP set-up of three (3) bioreactors was tested with a working volume of 0.8 L which comprises 0.5 L wastewater (WW) and 0.3 L activated sludge (AS) with 1.5g of the MNPs and a control system without MNPs. The degradation of chemical oxygen demand (COD) was increased with set-ups that contained MNPs as compared to the control system, MgFe2O4 (93.96%) > AlFe2O4 (85.95%) > control (68.83%). In terms of biogas production, the methane yield was also recorded as MgFe2O4 (85.7%) > AlFe2O4 (84.3%) > control (65.7%). The physical and chemical stability of MNPs makes them more advantageous for application in biogas production. In the prospects of biogas enhancement and biodegradability, integrating MNPs in an anaerobic digestion system will result in a more efficient anaerobic process performance for biogas production.

Magnetically recoverable, non-toxic, leach resistant aluminum ferrite (AlFeO3) photocatalyst for wastewater remediation

The practical use of photocatalyst in wastewater treatment is mainly hindered due to the recoverability of the catalyst. This can be addressed by the ferrite-based compounds which enable magnetic recoverability. In this work, Aluminium Ferrite (AlFeO3), a perovskite-based magnetic photocatalyst is successfully synthesized and its photocatalytic performance is tested. For the scale-up feasibility, the material is tested in static polluted water. AlFeO3 shows effective degradation of textile dye pollutants: 99% of Rhodamine B (RhB) in 180 min and 94% of Methyl orange (MO) in 270 min at the static condition, under visible-light illumination. It also exhibits UV photoactivity which implies AlFeO3 is a potential candidate for sunlight-driven wastewater treatment. The degradation rate is increased by 1.5 times when air is bubbled during photocatalysis. The catalyst is magnetically retrieved from the treated water and reused over 5 cycles with only ∼4% efficiency loss. The environmental viability of AlFeO3 is tested for the first time using cell toxicity studies and catalyst leaching in the treated water. The results indicate that more than 90% of L929 fibroblast cells are viable even when incubated with AlFeO3 for 24 h. The negligible trace of Al and Fe presence in the treated water shows that AlFeO3 is also leach resistant. Hence, AlFeO3 is a UV–Visible-light-driven, easy-to-recover, recyclable, and eco-friendly photocatalyst that has the potential for practical use.

CO2 Adsorption Reactions of Synthetic Calcium Aluminum Ferrite (CAF)

In this study, we investigated a mechanism of carbonation reaction by CO2 capture through synthesis of ternary (CaO-Al2O3-Fe2O3) compounds. As for the composition of the sintered calcium aluminum ferrite (SCAF), the proportions of CF-based product and CA-based product were high, at 87.3% and 64.6%, at sintering temperatures of 1000 °C and 1100 °C, respectively. In addition, in the process of both dry and wet carbonation, the carbonation reaction occurred in the synthetic SCAF regardless of the sintering temperature conditions. In particular, in the carbonation with the wet method, CAH and CAFH, which are hydrates, were produced in up to 1 h of the reaction time with CO2, but from 3 h of reaction time, carbo compounds such as calcium carbo aluminate and calcium carbo alumino-ferrite compounds were produced. That is, with increasing reaction time, the carbo reaction becomes more active in the process. Therefore, SCAF synthesized in this study easily produced carbo compounds through carbonation reactions and formed carbonates by reaction with CO2. Thus, it is expected that the compounds can be effectively utilized as an excellent material for CO2 capture capable of CO2 absorption and fixation.

Sentez Yöntemi ile LSAF Perovskit Morfolojisinin Ayarlanması

Lanthanum strontium aluminum ferrite (La0.8Sr0.2Al0.2Fe0.8O3±δ-LSAF) perovskites are drawing attention as cathodes in solid oxide fuel cells (SOFCs). The structural properties of these materials are mostly counting on the methods of preparation. In this study, two different preparation methods namely hydrothermal and sol-gel were applied to prepare LSAF perovskite. The characterization results including scanning electron microscopy (SEM), N2 adsorption-desorption, and Fourier transform infrared spectroscopy (FT-IR) are investigated in detail. The results showed that the preparation method played an important role on the microstructure of the LSAFs. It can be highlighted that the hydrothermal method is more successful in obtaining quite small nanoparticles.

Thermodynamic modeling of the synthesis of the main minerals of cement clinker from technogenic raw materials

In this article, thermodynamic studies of modeling the formation of the main minerals of cement clinker as a function of the Gibbs energy (ΔG) on temperature were investigated. The temperature range of the studies was 873-1873 K. In the course of modeling studies, the reactions of formation of cement clinker minerals (C2S - belite, C3S - alite, C3A – three calcium aluminates, C4AF – four calcium aluminium ferrite) from standard raw materials and non – standard-technogenic raw materials containing non-ferrous metals were calculated. Equations describing the dependence of the Gibbs energy on temperature with approximation coefficients (R2) equal to 0.99 are found. According to the results of the conducted studies, the beginning (Tb) temperatures of the course of the compared clinker formation reactions were determined, which were 1008 K for the standard reaction, and 1023 K for the non-standard reaction. It was found that the reactions begin to occur in the temperature intervals for the standard (1008 K – 1873 K), for the non - standard (1023 K - 1873 K). At the same time, the values at the initial stage of the course of the standard reaction have a more negative value of the Gibbs energy than the non-standard reaction. With a further increase in temperature, it becomes evident that the Gibbs energy of the non-standard reaction of mineral formation in the temperature range 1173-1873K becomes more negative in comparison with the values of the standard reaction and exceeds its values from 9 to 19.01%.

Physical properties of Al-doped cobalt nanoferrite prepared by citrate–nitrate auto combustion method

Cobalt aluminum ferrites have been synthesized by citrate–nitrate auto combustion method. To obtain different crystallite sizes, the prepared powder was heated at different temperatures. X-ray diffraction (XRD) measurements showed that all the prepared samples were crystalized in single phase cubic spinel structure. Different heat treatments lead to different particle sizes which was confirmed by transmission electron microscopy (TEM) micrograph. The crystallite size (D) of the prepared samples ranges from 5 to 37 nm. The structure and elastic properties were investigated using Fourier-transform infrared (FTIR) spectroscopy. The elastic moduli and Debye temperature were calculated out of the FTIR results. The magnetic properties were studied using vibrating sample magnetometer (VSM) and the magnetic parameters; saturation magnetization ( $$M_{\text {S}}$$ ) and coercitvity ( $$H_{\text {c}}$$ ) were determined. The $$M_{\text {S}}$$ and $$H_{\text {c}}$$ size dependence of CoFeAlO $$_{4}$$ nanoparticles introduce a distinctive behaviour; from a structure with multi magnetic domains ( $$D> 9$$ nm) to that without magnetic domains (single domain structure) below $$D= 9$$ nm. Interestingly, the signature of the change from multi-domain to a single magnetic domain is reflected in the size dependence of the elastic moduli and Debye temperature obtained from FTIR results.

Wideband (8–18 GHz) microwave absorption dominated electromagnetic interference (EMI) shielding composite using copper aluminum ferrite and reduced graphene oxide in polymer matrix

The development of an efficient radar absorbing material (RAM) is a need of the day due to rapid growth in satellite, electronic, and telecommunication industries (especially, in the GHz frequency region). Herein, an easy fabrication technique is presented to design a lightweight and flexible absorption dominated electromagnetic interference shielding material by dispersion of magnetic nanoparticles of a CuAl2Fe10O19 (CFA) decorated reduced graphene oxide (RGO) filler into the polyvinylidene fluoride (PVDF) matrix. This has been done by a simple chemical reduction method in the presence of hydrazine. It was observed that the synergetic effect of all filler contents along with multiple relaxation mechanisms due to the interface of RGO, CFA, and PVDF leads to strong absorption rather than reflection. This makes the composite an excellent candidate for RAM in the X band as well as in the Ku band. To develop a material for absorption in wideband frequencies is challenging, especially if the intended absorption is above 60 dB. In the present work, shielding efficiency (SE) of ∼60 dB in the X band and ∼50 dB in the Ku band has been achieved with more than 90% SE due to absorption. The effect of an individual filler content in wave attenuation has been analyzed from the point of view of absorption coefficient, complex permittivity and permeability, and attenuation constant.

Simultaneous sensing of copper, lead, cadmium and mercury traces in human blood serum using orthorhombic phase aluminium ferrite.

We report a facile, one-step solid-state synthesis of aluminium ferrite (AFO) for simultaneous sensing of heavy metal ions (HMIs) namely cadmium (Cd2+), lead (Pb2+), copper (Cu2+) and mercury (Hg2+) in human blood serum. The nanoflake morphology and orthorhombic phase formation of the as-synthesised AFO were revealed through field emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD) pattern, respectively. The AFO modified glassy carbon electrode (AFO/GCE) exhibits distinct peak potentials for all HMIs with peak separation potential (ΔΕP) of 190mV, 494mV and 304mV for Cd2+-Pb2+, Pb2+-Cu2+ and Cu2+-Hg2+, respectively. Low limits of detection (LOD) of values 1.5nM, 4nM, 1.6nM and 0.5nM were observed for Hg2+, Cd2+, Pb2+ and Cu2+, respectively which are well below the limits of unsafe concentrations of HMIs reported for human blood. The excellent sensitivity and low LOD can be attributed to the octahedral sites of the AFO perovskite structure with Fe2+/Fe3+ oxidation states which favours the delocalization of charge accumulations at the electrode surface. The sensor is successfully in determination of HMIs in simulated human blood serum using standard addition technique with an excellent recovery percentage. This strategy outlined here can be effectively used for developing various sensing platforms for bioanalytical applications.

Ultralow Damping in Nanometer-Thick Epitaxial Spinel Ferrite Thin Films.

Pure spin currents, unaccompanied by dissipative charge flow, are essential for realizing energy-efficient nanomagnetic information and communications devices. Thin-film magnetic insulators have been identified as promising materials for spin-current technology because they are thought to exhibit lower damping compared with their metallic counterparts. However, insulating behavior is not a sufficient requirement for low damping, as evidenced by the very limited options for low-damping insulators. Here, we demonstrate a new class of nanometer-thick ultralow-damping insulating thin films based on design criteria that minimize orbital angular momentum and structural disorder. Specifically, we show ultralow damping in <20 nm thick spinel-structure magnesium aluminum ferrite (MAFO), in which magnetization arises from Fe3+ ions with zero orbital angular momentum. These epitaxial MAFO thin films exhibit a Gilbert damping parameter of ∼0.0015 and negligible inhomogeneous linewidth broadening, resulting in narrow half width at half-maximum linewidths of ∼0.6 mT around 10 GHz. Our findings offer an attractive thin-film platform for enabling integrated insulating spintronics.

Flocculation of low algae concentration water using polydiallyldimethylammonium chloride coupled with polysilicate aluminum ferrite

ABSTRACTThe combined application of polydiallyldimethylammonium chloride (PDADMAC) and polysilicate aluminum ferrite (PSFA) was investigated to treat low algae density water samples, in which Microcystis aeruginosa is one of the dominant species. coagulation performance of M. aeruginosa was studied with regard to algal removal, Algal density was evaluated by determining the change in the optical density of the algal culture suspension at 680 nm and chlorophyll a. The dissolved organic matter, cellular morphology, viability, and recovery of M. aeruginosa cells after flocculation and sedimentation were also included. In addition, the effects of pH and addition order of PSFA and PDADMAC on algal removal were investigated. The removal efficiency of algae coagulated using combined PDADMAC and PSFA was improved by 34.5% and 19.3%, respectively. The organic matter removal was also enhanced. The optimum pH range for algal removal is 7.0–10.0, and the preferable addition sequence is the simultaneous addition of PDADMAC and PSFA. Scanning electron microscopy observation indicated that the combined usage of PDADMAC and PSFA caused no damage to the algal cell. Moreover, the experiment on algal recovery demonstrated that PDADMAC has bacteriostatic ability.

Magnetic Nanoparticles: Synthesis, Characterization and Magnetic Properties of Cobalt Aluminum Ferrite.

Nanoparticles of the ferrite system CoFe(2-x)Al(x)O4 (x = 0.0, 0.3, 0.7 and 1.0) were synthesized through the co-precipitation technique. Thermal decomposition process and formation of a single crystalline phase were followed using thermal differential analysis technique (DTA). X-ray powder diffraction patterns of the samples confirmed the formation of a nano-size single spinel phase. The average crystallite size was found to be in the range 20-63 nm for all samples. This was further confirmed by TEM of one of the samples, with concentration x = 1.0 which was found statistically to be 27 nm. This agrees well with the value of 24 nm deduced by means of X-ray diffraction method for the same sample. A considerable decrease in the intensity of the octahedral bands is observed as the aluminum concentration increases, and even vanishes completely at x = 1.0 indicating the migration of cations between the octahedral and tetrahedral sites. The magnetic hysteresis loops at room temperature showed decrease in both, coercivity and saturation magnetization as the non-magnetic Al3+ ions content increases. The relative values of M(r0/M(s) were found to be between 0.44 and 0.31 for the samples with a remarkable change in the squareness of the loops. This is highly beneficial for the microwave and memory devices applications of these nano sized ferrite system.

Preparation of Fe-doped colloidal SiO(2) abrasives and their chemical mechanical polishing behavior on sapphire substrates.

Abrasives are one of key influencing factors on surface quality during chemical mechanical polishing (CMP). Silica sol, a widely used abrasive in CMP slurries for sapphire substrates, often causes lower material removal rate (MRRs). In the present paper, Fe-doped colloidal SiO2 composite abrasives were prepared by a seed-induced growth method in order to improve the MRR of sapphire substrates. The CMP performance of Fe-doped colloidal SiO2 abrasives on sapphire substrates was investigated using UNIPOL-1502 CMP equipment. Experimental results indicate that the Fe-doped colloidal SiO2 composite abrasives exhibit lower surface roughness and higher MRR than pure colloidal SiO2 abrasives for sapphire substrates under the same testing conditions. Furthermore, the acting mechanism of Fe-doped colloidal SiO2 composite abrasives in sapphire CMP was analyzed by x-ray photoelectron spectroscopy. Analytical results show that the Fe in the composite abrasives can react with the sapphire substrates to form aluminum ferrite (AlFeO3) during CMP, which promotes the chemical effect in CMP and leads to improvement of MRR.

Structural and vibrational studies of NiAlxFe2−xO4 ferrites (0≤x≤1)

Nickel–Aluminium ferrites with the general formula NiAlxFe2−xO4 (0≤x≤1) were synthesized using the solid-state reaction technique and characterized using X-ray diffraction, FT-Infra Red and Raman spectroscopy. XRD diffraction patterns show that all samples have a pure single-phase cubic spinel structure over the whole composition range. From these patterns, the lattice parameter, bonds length, crystallite size, density and porosity have been calculated. Infra Red spectra showed two significant absorption bands, the high band corresponds to tetrahedral (A) sites and the lower band to octahedral [B] sites, thus confirming the single phase spinel structure. The force constants Kt and Ko for the two sites have been deduced from IR band frequencies and compared with the trend of bond lengths. For all compositions, Raman spectra show the five active modes A1g+E1g+3 T2g of the motion of O2− ions and both the A-site and B-site ions. The Raman frequencies trend with aluminium content show a blue shift for all modes consistent with the replacement of Fe3+ by lower mass Al3+.

Use of Spinel Nickel Aluminium Ferrite as Self-Supported Oxygen Carrier for Chemical Looping Hydrogen Generation Process

Chemical looping hydrogen generation (CLHG), as a new technology involved in chemical looping combustion (CLC) process and steam-iron process, has attracted attention for clean energy generation and efficient energy conversion. A systematic investigation of spinel NiFeAlO4 has led to characterization of a well-defined self-supported oxygen carrier which was prepared by solid state reaction. The redox behavior of NiFeAlO4 shows the enhancement on the resistance to agglomeration exceeding previously reported CLC process using similar compositions including Fe2O3, NiO and NiFe2O4 without any inert support. Moreover, the high CO2 conversion and H2 generation by NiFeAlO4 oxygen carrier under a fixed-bed reactor (FxBR) were obtained. The reaction mechanism of NiFeAlO4 subjected to the isothermal stepwise reduction in a sequence of varying durations by XRD was also demonstrated, which provided with a novel function of self-supported and agglomeration-resistant characteristic in the oxygen carrier system.

Synthesis and spectroscopic characterization of copper zinc aluminum nanoferrite particles

Copper doped zinc aluminum ferrites CuxZn1−x.(AlxFe2−x)O4 are synthesized by the solid-state reaction route and characterized by XRD, TEM, EPR and non linear optical spectroscopy techniques. The average particle size is found to be from 35 to 90nm and the unit cell parameter “a” is calculated as from 8.39 to 8.89Å. The cation distributions are estimated from X-ray diffraction intensities of various planes. The XRD studies have verified the quality of the synthesis of compounds and have shown the differences in the positions of the diffraction peaks due to the change in concentration of copper ions. TEM pictures clearly indicating that fundamental unit is composed of octahedral and tetrahedral blocks and joined strongly. The selected area electron diffraction (SAED) of the ferrite system shows best crystallinity is obtained when Cu content is very. Some of the d-plane spacings are exactly coinciding with XRD values. EPR spectra is compositional dependent at lower Al/Cu concentration EPR spectra is due to Fe3+ and at a higher content of Al/Cu the EPR spectra is due to Cu2+. Absence of EPR spectra at room temperature indicates that the sample is perfectly ferromagnetic. EPR results at low temperature indicate that the sample is paramagnetic, and that copper is placed in the tetragonal elongation (B) site with magnetically non-equivalent ions in the unit cell having strong exchange coupling between them. This property is useful in industrial applications. Nonlinear optical properties of the samples studied using 5ns laser pulses at 532nm employing the open aperture z-scan technique indicate that these ferrites are potential candidates for optical limiting applications.