Strontium Ferrite Research Articles

Evaluating the dynamic‐mechanical and thermal stability of polyphenylene sulfide composites filled with magnetic filler for sensor applications

AbstractIsotropic polyphenylene sulfide (PPS) composites filled with the magnetic fillers strontium ferrites (SrFeO) and neodymium iron boron (NdFeB) at two concentrations of 52 vol.% and 60 vol.% were prepared by the injection molding technique without use of an external magnetic field. Frequency sweeps shows that the mechanical frequency has little influence on the strength of all PPS samples and only ensures a higher mobility of the PPS chain ends at high frequency. Increasing the magnetic filler content and the use of NdFeB instead of SrFeO provide the PPS composites a larger structural robustness making them more resistant to mechanical loads and mechanically more stable. The temperature behavior of the PPS composites shows independently of the filler a strong softening from 80 °C. Nevertheless, larger operating temperatures below the glass transition temperature appear realistic.

Magnetic properties of PDMS embedded with strontium ferrite particles cured under different magnetic field configurations

Flexible materials embedded with hard magnetic particles have recently gained widespread recognition as small-scale actuators due to their capacity to be a rapid and precise shape-shifting material. Strontium ferrite (SrFe12O19) particles have been shown as a great candidate for such applications, since it is an inert hard magnetic material that, in contrast to barium ferrite and neodymium, is also biocompatible. The preparation of such material is done by mixing the magnetic particles into the uncured elastomer (polydimethylsiloxane (PDMS)), in liquid form, and then pouring the mixture in a mold for curing. If the samples are subjected to a magnetic field during the curing process, chains of particles are formed in the direction of the applied field, thus creating an easy axis in this same direction. The magnetic properties of such composite cannot yet be found in literature. In this study, we analyzed three concentrations of strontium ferrite particles in PDMS under three field configurations, resulting in 9 different samples. The concentrations used were 1:1, 2:1, and 4:1 ratios of PDMS to strontium ferrite per weight. All three types of samples were cured either in a zero magnetic field, or over the north pole of a neodymium permanent magnet, or over the side of said magnet. A biaxial vibrating sample magnetometer (VSM) was used to measure hysteresis curves parallel and perpendicular to the curing field. The samples cured in a field show a squareness ratio of up to 0.94 while the samples cured in zero field, only close to 0.5. The samples cured in a field show a magnetic anisotropy with an easy axis parallel to the curing field. Harvesting these modified properties, a mobile robot manufacturing method is proposed that bypasses the need of applying a high intensity magnetic field.

Low-Cost Inorganic Strontium Ferrite a Novel Hole Transporting Material for Efficient Perovskite Solar Cells.

Perovskite solar cells attract significant interest due to their high-power conversion efficiencies. The replacement of charge-transporting layers using inorganic materials is an effective approach for improving stability and performance, as these materials are low-cost, highly durable, and environmentally friendly. This work focuses on the inorganic hole and electron transport layers (HTL and ETL), strontium ferrite (SrFe2O4), and zinc oxide (ZnO), respectively, to enhance the efficiency of perovskite solar cells. Favorable band alignment and high charge-collection capability make these materials promising. Experimental and computational studies revealed that the power conversion efficiency of the fabricated device is 7.80% and 8.83%, respectively. Investigating electronic properties and interface charge transfer through density functional theory calculations further corroborated that SrFe2O4 is a good HTL candidate. Our numerical device modeling reveals the importance of optimizing the thickness (100 nm and 300 nm) of the HTL and perovskite layers and defect density (1016 cm−3) of the absorber to achieve better solar cell performance.

Strontium ferrite as a nontoxic nanomaterial to improve metabolism in a diabetic model of Drosophila melanogaster

Nanomaterials have gained enormous importance in the last few decades in various fields including medical science. Diabetes is one of the most serious health concerns, which remain untreated due to inherent drug deficiencies and limitations of administration routes, such as the adverse effects of prolonged subcutaneous injection and challenges involved in oral administration. Besides this, huge treatment cost of the used therapies often leads to huge burden to the patients. The current study describes synthesis of hexagonal strontium ferrite nanomaterials and checked their potentiality to reduce the metabolic effects in a Drosophila model of diabetes. The nanomaterials were prepared by a low-cost digital ultrasonic wave method and characterized using FTIR and XRD to determine the corresponding functional groups. The obtained XRD pattern was fitted with Rietveld refinement method for structural analysis, which shows that the samples crystallized have a hexagonal crystal lattice with the space group P63/mmc. FESEM and EDS analysis were performed for surface analysis showing the average size of the nanoparticles as 600 nm and high weight percentage of Sr and Fe. The Zeta potential of SrFe was also carried out to analyze the surface charge. To validate the non-toxicity of the nanomaterials, various concentrations of SrFe were mixed with the food and orally administered to Drosophila melanogaster model system. Behavioral activities and gut morphology of third instar larvae were checked, which showed toxic effects only at the high concentration of treatment (80 μg/ml). SrFe impacts the hatching percentage of pupa and the adult as well as fly survival which showed an increase in survival percentage. Diabetic flies were generated by feeding on a high-fat diet (HFD) and treated with the nanomaterials. A dose-dependent decrease in the metabolic level was seen in the treated flies. A significant improvement in the fly weight and reduced ROS level was also observed in the diabetic flies after SrFe treatment. Thus, the current study reports the use of SrFe nanomaterial as a non-cytotoxic and non-genotoxic material having potentiality to be used in the treatment of metabolic disorder alone or as a combinational therapy.

Enhanced magnetic properties of strontium ferrites through constructing magnetoelastic stress

Strontium ferrites, which exhibit large remanence, high coercivity (Hc), are fascinating for applications in motors and high-frequency microwave devices. Here we demonstrate the strontium ferrites (Sr0.34Ca0.25La0.41Fe11.4Co0.19O19-δ) sintered at 1150 °C with enhanced magnetic properties through constructing magnetoelastic stress. The effects of applied pressure (Pc-axis) of 0–16 kPa during the sintering process on phase compositions, morphologies, magnetic and microwave properties are investigated in detail. We note that the Pc-axis could contribute to enhanced c-axis preferred orientation. This mechanism of enhancement has been also discussed according to the magnetoelastic theory. By applying an external pressure of 8 kPa, intrinsic coercivity (Hcj) of 4657 Oe and magnetic coercivity (Hcb) of 3781 Oe are obtained. The increments are 8.1% and 18.0% for Hcj and Hcb, respectively, compared to the sample with Pc-axis of 0 kPa. However, the enhancement of Hc by the Pc-axis is seen to be limited above 8 kPa, which can be attributed to the enlarged grain size and porosity observed. In addition, the ferromagnetic resonance frequency (fr) is also increased by the increased Pc-axis.

Recent advances in heteroatom substitution Sr2Fe1.5Mo0.5O6–δ oxide as a more promising electrode material for symmetrical solid-state electrochemical devices: A review

In recent years, the interest in solid state electrochemical devices has significantly increased due to the various cases of their use in the energy field. The first case is the solid oxide fuel cells with both oxygen-ion and proton-conducting membranes. The second case is the electrolysis cells for hydrogen production. As a rule, in both cases, electrochemical cells consist of an ion-conducting membrane and two different electrodes. The present review is focused on structural, physicochemical, and electrochemical properties of a complex oxide based on strontium ferrite with partial replacement of iron by molybdenum. This complex oxide has a number of unique characteristics: in particular, it is able to function effectively as an electrode in oxidizing and strongly reducing atmospheres, which makes it a promising material for electrochemical devices based on solid electrolytes with symmetrical electrodes. Doping with elements in A-, B- and O-sublattices and surface modification increases electro-catalytic activity of Sr2Fe1.5Mo0.5O6−δ porous oxide material, which increases competitiveness of the electrode material for application in solid oxide electrochemical devices. Mechanisms for improving electro-catalytic activity are outlined stepwise by doping of different sublattices of double perovskite, by level of doping, and by different types of dopants. In conclusion, the data on material conductivity, power densities of both symmetric and fuel cells are systematized, and the remaining problems and prospects for future developments and upgrades of Sr2Fe1.5Mo0.5O6−δ oxide electrode material are described.

Effect of Ca2+ on the Microstructure, Morphology and Magnetic Properties of La-Co Substituted M-Type Strontium Ferrite at Low Fe Content

Effect of Ca2+ on the Microstructure, Morphology and Magnetic Properties of La-Co Substituted M-Type Strontium Ferrite at Low Fe Content

Effect of Doping Ratio on Thermal, Microstructural and Magnetic Properties of Differently Doped Strontium Ferrites Synthesized by a Facile Co-Precipitation Method

Effect of Doping Ratio on Thermal, Microstructural and Magnetic Properties of Differently Doped Strontium Ferrites Synthesized by a Facile Co-Precipitation Method

Synthesis of magnetic nanoparticles by laser ablation of strontium ferrite under water and their characterization by optically detected magnetophoresis supported by BEM calculations

Optically detected magnetophoresis, using Boundary Element Method calculations, is exploited for characterizing the magnetic properties of low amounts of nanoparticles.

Strontium Ferrite Srfeo3-Δ (2.50 ≤ 3-Δ ≤ 2.87) Studied by Raman and Mössbauer Spectroscopy

Strontium Ferrite Srfeo3-Δ (2.50 ≤ 3-Δ ≤ 2.87) Studied by Raman and Mössbauer Spectroscopy

Study on Electrical and Magnetic Properties of Nd-Co Co-Substituted M-Type Strontium Ferrite Suitable for Microwave Devices

Study on Electrical and Magnetic Properties of Nd-Co Co-Substituted M-Type Strontium Ferrite Suitable for Microwave Devices

Study on the Effect of Ca Content and Fe Content on the Structure and Magnetic Properties of M-Type Strontium Ferrite

Study on the Effect of Ca Content and Fe Content on the Structure and Magnetic Properties of M-Type Strontium Ferrite

Feasibility of producing cement-based sacrificial materials with strontium ferrite: A preliminary study

The safety of nuclear power plant can be improved via core catcher, and cement-based sacrificial materials are widely used in most core catchers because of their simple construction process and the low manufacturing cost. This paper carried out a preliminary investigation to explore the feasibility of using strontium ferrite to prepare cement-based sacrificial materials. The effects of strontium ferrite on the room temperature and high temperature properties of cement mortar were systematically studied in the work. In addition, the damage evolution of cement mortar containing strontium ferrite subjected to elevated temperatures was also identified according to the damage mechanics theory. It was found that, (1) the addition of strontium ferrite led to the deterioration of the mechanical properties, microstructure and pore structure of cement mortar; (2) it was feasible to prepare cement-based sacrificial materials containing strontium ferrite that met the requirements on basic properties like mechanical properties, free water content, volume stability, and the high temperature integrity by controlling the content of strontium ferrite; (3) the correlation between the internal damage of cement mortar and the temperature could be described by Weibull Distribution Model, which provided a basis for the identification and evaluation of serious nuclear power accidents.

Soft/hard ferrite nanocomposites: Evaluation of temperature dependent dielectric properties

Nanocomposites of cobalt ferrite (CoFe2O4) and strontium ferrite (SrFe12O19) were synthesized with various weight ratios 1:1, 1:2, 1:4, 1:8 and 1:16, by chemical co-precipitation route with higher content corresponding to SrFe12O19. Dual phase refinement employed for the prepared composites and confirms the presence of independent CoFe2O4 and SrFe12O19 phases. The increasing weight fraction of SrFe12O19 in the prepared composites is in accordance with its increasing weight ratio. An increase in compressive strain in the composites was attributed to larger ionic radius of Sr+2 ions. The electrical behavior in the composites was described by Cole-Cole plots at 250 °C from 20 Hz-106 Hz. An increase in impedance with increasing weight ratio of SrFe12O19 was observed, due to creation of effective scattering centers. Conductivity mechanism was explained by Overlapping large polaron tunneling (OLPT) model. A decrease in dielectric constant with increasing frequency is due to decreasing space charge polarization, due to inability of charge carriers to follow the varying ac field. Decreasing trend in dielectric loss for the prepared composites confirms their utility in microwave absorption applications.

Structural and tunable dielectric properties of cobalt ferrite-based nanocomposites

Nanocomposites C:S-1:4 comprising cobalt ferrite (CoFe2O4), strontium ferrite (SrFe12O19) and C:B-1:4 containing cobalt ferrite (CoFe2O4), barium ferrite (BaFe12O19) were synthesized in weight ratios of 1:4 by chemical co-precipitation route with higher content corresponding to SrFe12O19 and BaFe12O19. Rietveld refinement was employed to confirm the presence of independent CoFe2O4, SrFe12O19 and BaFe12O19 phases. The average crystallite size of CoFe2O4 and SrFe12O19 in C:S-1:4 was observed as 20 nm and 56 nm which depicts an increase as compared to individual components. The observed lattice strain in C:S-1:4 was 0.05% and 0.03% for CoFe2O4 and SrFe12O19. In C:B-1:4, the value of strain was 0.06% and 0.04% for CoFe2O4 and BaFe12O19. Increased lattice strain was observed in the prepared composites. Increase in impedance for the prepared composites was observed from measurements performed in the frequency range 20 –106 Hz. Conduction mechanism was explained by overlapping large polaron tunneling model. Dielectric loss measurements for the prepared composites were observed to decrease establishing their usage in microwave applications.

Effect of La-Cu co-substitution on structural, microstructural and magnetic properties of M-type strontium hexaferrite (Sr1−xLaxFe12−xCuxO19)

The copper substituted various stochiometric compositional nano hexagonal ferrites of Sr1−xLaxFe12−xCuxO19 (x = 0.0, 0.05, 0.1, 0.15 and 0.2) are synthesized successfully via sol–gel auto-combustion method and subsequently sintered the samples at a temperature of 1200 °C/2 hrs. We observed the effect of La-Cu substitution on the structural and magnetic properties of hexagonal strontium ferrites. X-ray diffraction pattern reveals monophasic magnetoplumbite hexagonal structure with a space group of P63/mmc, chemically pure, nanocrystalline, and magnetically ordered particles with magnetic properties. The unit cell parameter (a = b) unit cell parameter is found to decrease 5.896 Å to 5.857 Å whereas, crystallite sizes were observed to decrease from 36.28 nm to 20.07 nm with the increase in doping. FTIR spectra reveals the presence of octahedral and tetrahedral vibrational modes near 400 cm−1 and 600 cm−1 respectively which confirms the formation of hexaferrite phase. Saturation magnetization (Ms) increased from 62.37 emu/g to 67.27 emu/g with the increase in doping.

Preparation of Hollow Spherical Particles of Strontium Ferrite SrFe12O19 by Spray-Pyrolysis

Preparation of Hollow Spherical Particles of Strontium Ferrite SrFe12O19 by Spray-Pyrolysis

Synthesis of strontium ferrite and its role in the removal of methyl orange, phenolphthalein and bromothymol blue from laboratory wastewater

The presence of organic chemical pollutants such as methyl orange (MOIn), phenolphthalein (PhIn) and bromothymol blue (BBIn) in laboratory wastewater is a challenge which requires immediate attention. In response to this challenge, strontium ferrite (SrFe2O4) was prepared via co-precipitation method as an adsorbent for the removal of these pollutants from laboratory wastewater. SrFe2O4 was characterized by Fourier Transform Infrared spectrometer (FTIR), X-ray Diffraction analysis (XRD), Energy Dispersive X-Ray Spectroscopy (EDS), and Scanning Electron Microscopy (SEM). FTR, XRD and RDS results confirmed the identity of SrFe2O4. SEM shows particles of SrFe2O4 of different dimensions and shapes, that reveal the coexistence of both monocrystalline and polycrystalline particles. The adsorption of the contaminants from aqueous solutions on SrFe2O4 was studied in a batch system. The results showed that the adsorption is affected by the initial contaminant concentration (1.00–5.00 mg L−1), adsorbent dosage (0.05–0.10 g), adsorption temperature (303–323 K), and pH (2.1–11.0). SrFe2O4 removes the pollutants from water with adsorption capacities (7.00–8.60 mg g−1) and percentage removals (70.00–86.00%) that compared favourably with other previously reported adsorbents. The removal of the pollutants by SrFe2O4 obeys the pseudo-first-order model which can be described by the Langmuir isotherm model. The Gibb's free energy change (∆Go) and enthalpy change (∆Ho) for the sorption process were negative while the entropy change (∆So) was found to be 0.205, 0.282 and -0.221 kJ mol−1K−1 for MOIn, PhIn and BBIn respectively. The adsorption mechanism was considered to occur via electrostatic interaction. Regeneration capacities expressed by SrFe2O4 were above 70% even after the 12th regeneration cycle. The sorption process was further described in molecular terms using computational quantum mechanical modelling, density functional theory (DFT). The use of SrFe2O4 for the treatment of raw laboratory wastewater is effective towards the removal of MOIn, PhIN and BBIn.

Solid-state compatibility of Ca:LaNbO4 with perovskite cathodes: Evidences from X-ray microspectroscopy

The solid-state compatibility between calcium-doped lanthanum niobate and three perovskite cathode materials was investigated using two X-ray microbeam techniques, micro X-ray fluorescence and micro X-ray absorption spectroscopy. The cathode powders (lanthanum strontium ferrite, either cobalt or copper-doped, and lanthanum strontium cobaltite) in contact with the dense electrolyte pellet were annealed at 1150°C for 12–144 h to simulate the effect of thermal stresses due to fabrication and long-term operation. As a result, several interdiffusion phenomena were then observed on the bilayer cross-sections: in particular, the chemical state and coordination environment of calcium, iron, niobium and lanthanum were probed with space-resolved X-ray absorption spectroscopy. The ab initio modeling of the near-edge X-ray absorption spectra reveal that the cation interdiffusion is facilitated by the structural flexibility of the perovskite structure, which is able to accommodate a variety of foreign cations in different oxidation states. Limited stability at high-temperatures was found for all candidate perovskite compositions in contact with lanthanum niobate.

Injection Moulding of Multipolar Polymer-Bonded Magnets into Soft Magnetic Inserts for Rotors in Reluctance Motors

Due to lower magnetic properties of polymer-bonded magnets compared to sintered magnets, a complete redesign of the multipolar soft magnetic flux barriers in rotors with alignment guidelines was carried out to eliminate the frequently used rare-earth magnets, causing a new influence of the outer magnetic field on the cavity by using soft magnetic inserts. Within this new process, the main influencing factors on the magnetic flux density such as filler content, tool temperature, holding pressure and injection velocity were analysed and correlated. The studies were based on the compound of Polyamide 12 and up to a 60 vol.-% of the hard magnetic filler, strontium ferrite. Based on the study, the injection moulding of multipolar-bonded magnets into soft magnetic inserts for rotors and, in turn, into complex geometries can be optimized in terms of the orientation of the filler, the microstructure and the magnetic flux density. The investigations show no significant influence of the process parameters known from the literature such as the mass temperature Tm, which affects the magnetic flux density, as well as the orientation and the microstructure similar to tool temperature Tt, but is less efficient. The main influencing factors identified during the investigations are the tool temperature Tt, the injection velocity vin and the holding pressure ph. As known influencing factors are only based on simple geometries such as ring structures or plates, new factors were determined for complex rotor geometries.