Strontium Ferrite Nanoparticles Research Articles

Lightweight carbon foam composites embedded with RGO/SrFe12O19 hybrid: Fabrication, structural and electromagnetic shielding performance in 8.2 to 12.4 GHz

Today's growth of wireless technology has increased the demand for composite materials with absorption-based shielding capabilities and the composites of dielectric and magnetic materials are suitable for producing high shielding effectiveness (SE). The present study establishes a facile way to synthesize carbon foam embedded with strontium ferrite (SrFe12O19) nanoparticles decorated within/ on reduced graphene oxide (RGO) sheets. In this work, polyurathene templete slab is dipped in the homogenous slurry prepared from RGO/SrFe12O19 (RS) hybrid and phenolic resin followed by carbonization to produce the CF/RGO/SrFe12O19 (CRS) composite foam. The synthesized CRS3 nanocomposite foam exhibits maximum shielding effectiveness due to an absorption (SEA) value of 26.6 dB i.e., ∼99.7% attenuation, and absolute specific shielding effectiveness (SSEt) value of 250.70 dBcm2g–1. The high SEA value of synthesized composite carbon foam is obtained because of the synergistic effect of porous morphology, dielectric losses and magnetic losses.

Abatement of microbes and organic pollutants using heterostructural nanocomposites of rice straw CQDs with substituted strontium ferrite

Sustainable use of agricultural waste still remains a challenging task. Herein, we used rice straw as a carbon precursor to prepare carbon quantum dots (CQDs) for photocatalytic applications. Nanocomposites of CQDs with Ti4+ and Mg2+ substituted strontium ferrite (Sr0·4Ti0·4Mg0·2Fe2O4.4) nanoparticles (NPs) in varying w:w ratio was synthesized by ultrasonication method. The successful formation of nanocomposites was confirmed by various microscopic and spectroscopic techniques. The photocatalytic and antibacterial activity of NPs, CQDs and nanocomposites was comparatively evaluated using tetracycline hydrochloride, azure B, Staphylococcus aureus and Escherichia coli as model pollutants. The CQDs-Sr0.4Ti0·4Mg0·2Fe2O4.4 nanocomposite with a w:w ratio of 2:1 showed excellent photocatalytic and antibacterial activity, with the degradation and inactivation efficiency ranging from 97.1% to 99.0% in presence of visible light. The increased specific surface area (117.2 m2/g), and reduction in band gap (2.48 eV–2.09 eV) and decreased photoluminescence intensity of nanocomposites all corroborated these results. The impacting experimental parameters such as catalyst dose, pH and contact time were also examined. Quenching experiments confirmed that hydroxyl radicals (HO∙) radicals and holes (h+) played a vital role in the degradation of pollutants. The kinetics of photodegradation was explained by using the Langmuir-Hinshelwood model. Box-Behnken statistical modelling was used to optimize photocatalytic parameters. Results indicated that the nanocomposite of CQDs with Sr0·4Ti0·4Mg0·2Fe2O4.4 can serve as a promising photocatalyst for the removal of pollutants and microbes.

Correction: Structural and optical studies on Ti4+ and Mg2+-substituted strontium ferrite nanoparticles for enhancing visible-light-driven photocatalytic and antimicrobial activity

Correction: Structural and optical studies on Ti4+ and Mg2+-substituted strontium ferrite nanoparticles for enhancing visible-light-driven photocatalytic and antimicrobial activity

Single-Domain Hard Ferromagnetic M-SrFe Nanoparticles for Magnetic Data Storage

Single-domain M-type Strontium Ferrite nanoparticles are prepared by the co-precipitation method. The crystallite size of the M-SrFe Nps is 58.1 nm, as determined by the XRD pattern. The SEM micrographs reveal the hexagonal morphology. M-SrFe Nps is depicted in EDS analysis. According to VSM characterization, the sample is a hard magnetic material with high coercivity. With its outstanding magnetic characteristics, hexaferrite is typically employed in permanent magnetic materials and recording devices. The band gap energy is determined to be 1.95 eV from the UV-DRS reflectance data using the Kubelka-Munk plot. The absorbed wavelength with the highest intensity peak in PL analysis is 629.9 nm. The TG-DTA investigations support the remarkable thermal stability of M-SrFe Nps. The resistivity of the sample, 0.312 Ωm is calculated using the four-probe method.

Structural and optical studies on Ti4+ and Mg2+-substituted strontium ferrite nanoparticles for enhancing visible-light-driven photocatalytic and antimicrobial activity

Structural and optical studies on Ti4+ and Mg2+-substituted strontium ferrite nanoparticles for enhancing visible-light-driven photocatalytic and antimicrobial activity

Effects of calcination temperatures on structural, functional, morphological, and magnetic properties of strontium ferrite (SrFe2O4) nanoparticles

In this proposed work, the strontium ferrite (SrFe2O4) nanoparticles were successfully synthesized in the presence of strontium nitrate (Sr (NO3)2) and ferric nitrate (Fe (NO3).9H2O) as primary sources by using chemical co-precipitation method. The prepared powders were kept different calcinations temperature (650, 750 and 850 ​°C) and characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) and vibrating sample magnetometer (VSM) techniques. The XRD patterns demonstrated the cubic and orthorhombic phase of spinel formation and FTIR transmittance spectra confirmed the presence of strontium ferrite related molecular functional groups. Further, SEM micrograph showed spherical nanoparticles with less agglomerated structure. VSM studies revealed the hard magnetic properties with the highest saturation magnetization (Ms), remanent magnetization (Mr) and coercivity (Hc) of 22.17 emu/g, 11.807 emu/g and 5662.6 ​Oe respectively by VSM.

Effect of multi-wall carbon nanotubes/strontium ferrite nanoparticles on the microstructure, phase, magnetic and electromagnetic behavior of carbon aerogel composites

This research examined the electromagnetic behavior of a carbon aerogel composite containing multi-wall carbon nanotubes and strontium ferrite nanoparticles within the X band range (8.12–2.4 GHz). For this purpose, 10 wt% of carbon nanotubes and 5 wt%, 10 wt%, and 15 wt% of strontium ferrite nanoparticles were applied in the pyrolyzed cellulose aerogel composite. For structural and magnetic characterization of the samples, different techniques such as X-ray diffraction test, Fourier transform infrared spectroscopy, field emission scanning electron microscopy, vector network analyzer, and vibrational magnetometer (VSM) were used. The VSM results indicated that the presence of 10 wt% strontium ferrite nanoparticles in the carbon aerogel substrate caused saturation magnetization of 2.31 emu/g. However, upon adding 10 wt% carbon nanotubes, the saturation magnetization value reached 6.82 emu/g. Based on the results, the greatest shielding efficiency (within the X-band = 110 ± 0.8 dB) occurred in the sample containing 10 wt% carbon nanotube alongside 5 wt% strontium ferrite at thicknesses of 4 mm. Furthermore, the reflection loss value of this sample was −48.59 ± 0.5 dB at a thickness of 3 cm and a frequency of 10.92 GHz.

Structural and Photocatalytic Studies on Oxygen Hyperstoichiometric Titanium-Substituted Strontium Ferrite Nanoparticles

Doping of ferrites is an important domain of research for their application as photocatalysts. In the present work, the effect of Ti4+ substitution on the structural and photocatalytic properties of strontium ferrite nanoparticles (NPs) is studied. Ternary doped Sr1−xTixFe2O4+δ ferrite NPs (x = 0.0–1.0) were synthesized by sol–gel methodology. Tetravalent Ti4+ ions caused oxygen hyperstoichiometry and enhancement in the surface area from 44.3 m2/g for SrFe2O4 NPs to 77.6 m2/g for Sr0.4Ti0.6Fe2O4+δ NPs. The average diameter of NPs ranged between 25–35 nm as revealed by TEM analysis. The presence of two sextets in the Mössbauer spectrum of pristine SrFe2O4 and Ti4+-substituted ferrite NPs and a paramagnetic doublet in the TiFe2O5 confirmed their phase purity. The photocatalytic potential of pure and Ti4+-substituted ferrite NPs was studied using nitroaromatic compounds, viz. pendimethalin, p-nitrophenol and Martius yellow, as model pollutants. Doped ferrite NPs with a composition of Sr0.4Ti0.6Fe2O4+δ NPs showed the highest degradation efficiency ranging from 87.2% to 94.4%. The increased photocatalytic potential was ascribed to the lowering of band gap (Eg) from 2.45 eV to 2.18 eV, a fourfold decrease in photoluminescence intensity, increased charge carrier concentration (4.90 × 1015 cm−3 to 6.96 × 1015 cm−3), and decreased barrier height from 1.20 to 1.02 eV. O2●− radicals appeared to be the main reactive oxygen species involved in photodegradation. The apparent rate constant values using the Langmuir–Hinshelwood kinetic model were 1.9 × 10−2 min−1, 2.3 × 10−2 min−1 and 1.3 × 10−2 min−1 for p-nitrophenol, pendimethalin and Martius yellow, respectively. Thus, tuning the Ti4+ content in strontium ferrite NPs proved to be an effective strategy in improving their photocatalytic potential for the degradation of nitroaromatic pollutants.

Visible light driven instantaneous photocatalytic degradation of aniline blue (AB) and methyl violet (MV) by strontium ferrite nanoparticles

AbstractToxic organic dyes released into aquatic sources as a result of industrial activities pose a significant threat to the environment. The removal of such dyes from water sources is a challenging task in the context of environmental emergencies. In this present effort, the strontium ferrite nanoparticles were synthesized by coprecipitation followed by a calcination method and is applied for photocatalytic degradation of such organic dyes. The ferrite nanoparticles were characterized by FTIR, XRD, VSM, SEM‐EDX, TEM, and HR‐TEM studies. In the existence of H2O2 under visible light, the catalyst performs efficient degradation of aniline blue (AB) and methyl violet (MV) dyes in a remarkably short interval of time. The superparamagnetic performance of the catalyst was confirmed by VSM, and thus it can be easily recovered from the degraded dye by applying an external magnet. The Fenton mechanism justifies the elevated rate of photo degradation, which generates hydroxyl and perhydroxyl radicals in the progress of the reaction.

The effects of strontium ferrite micro-and nanoparticles on the microstructure, phase, magnetic properties, and electromagnetic waves absorption of graphene oxide-SrFe12O19-SiC aerogel nanocomposite

In this work, ultralight electromagnetic (EM) wave absorbent based on the graphene oxide (GrO) nanocomposite was investigated. This research aims to fabricate an aerogels nanocomposite made of GrO as an aerogel matrix and the absorbent of the electrical part of EM waves, strontium ferrite nanoparticles as an absorbent of the magnetic portion of EM waves, silicon carbide as a dielectric nanoparticle for further EM waves absorption. To prepare the graphene oxide aerogel - strontium ferrite - nano silicon carbide nanocomposite, the hydrothermal - freeze-drying method was used. The effects of strontium ferrite micro-and nanoparticles on the microstructure, phase, magnetic properties, and electromagnetic waves absorption were investigated. Results show that aerogel with nano-sized particles possesses a better EM absorbing performance than the micro-sized particles due to better impedance matching and nanosize effect.

Magnetic hydrogel based shoe insoles for prevention of diabetic foot

Currently, plastic/rubber/silicone based shoe inserts are used as preventive approach against diabetic foot which are non-degradable, non-absorbent and contains magnet protrusions, making them highly uncomfortable. These are discarded and thrown away after their service life, causing soil and marine pollution. Thus, the objective of this study was to evaluate polyvinyl alcohol/carboxymethyl cellulose (PVA/CMC) based magnetic hydrogels prepared by physical crosslinking as an alternative for diabetic shoe inserts. Hydrogels prepared by moist heat treatment with different concentration of strontium ferrite nanoparticles (MG) are evaluated based on their structural, physico-chemical, morphological, thermal, mechanical, thermo-mechanical, swelling behavior, surface wetting, magnetic and rheological properties. It was observed that incorporation of MG resulted in improvement in overall properties. Infrared spectroscopy revealed strong hydrogen bonding interaction between CMC and PVA. The surface micrographs showed uniform dispersion of MG throughout PVA/CMC matrix. The results showed the improvement in flexibility and tensile strength of the PVA/CMC hydrogels with the incorporation of MG by ~40 and ~20%, respectively. Moreover, the magnetic hydrogels could absorb ~300% moisture of their original weight which is necessary to avoid growth of microbes on skin. Thus, PVA/CMC/MG hydrogels can be considered as a biodegradable alternative for diabetic shoe insoles.

New reed switch design based on magnetic silver

A new composite magnetic material — silver doped with strontium ferrite nanoparticles (SFO NPs) — opens the way to the construction of reed switches which are based on a new design, which utilizes the fact that the SFO@Ag is metallic-conductive and magnetic at the same time. The induction of magnetism in the inert and stable conductive metals, as well as the use of powder instead of failure-prone metallic reeds, makes this new switch design attractive. Both the magnetic and conductive properties of the switch can be controlled by changing the percentage of the entrapped SFO NPs. This affects the magnetic saturation moments of the composites and the resistivity, as also shown by Hall Effect measurements.

Microwave absorption properties of reduced graphene oxide strontium hexaferrite/poly(methyl methacrylate) composites

The key factors to consider when designing microwave absorber materials for eradication of electromagnetic (EM) pollution are absorption of incident EM waves and good impedance matching. By keeping these things in mind, flexible microwave absorber composite films can be fabricated by simple gel casting techniques using reduced graphene oxide (RGO) and strontium ferrite (SF) in a poly(methyl methacrylate) (PMMA) matrix. SF nanoparticles are synthesized by the well known sol–gel method. Subsequently, reduced graphene oxide (RGO) and SF nanocomposite (RGOSF) are prepared through a chemical reduction method using hydrazine. The structure, morphology, chemical composition, thermal stability and magnetic properties of the nanocomposite are characterized in detail by various techniques. The SF particles are found to be nearly 500 nm and decorated on RGO sheets as revealed by field emission scanning electron microscopy and transmission electron microscopy analysis. Fourier transform infrared and and Raman spectroscopy clearly show the presence of SF in the graphene sheet by the lower peak positions. Finally, ternary polymer composites of RGO/SF/PMMA are prepared by an in situ polymerization method. Magnetic and dielectric studies of the composite reveal that the presence of RGO/SF/PMMA lead to polarization effects contributing to dielectric loss. Also, RGO surrounding SF provides a conductive network in the polymer matrix which is in turn responsible for the magnetic loss in the composite. Thus, the permittivity as well as the permeability of the composite can be controlled by an appropriate combination of RGO and SF in PMMA. More than 99% absorption efficiency is achieved by a suitable combination of magneto-dielectric coupling in the X-band frequency range by incorporating 9 wt% of RGO and 1 wt% of SF in the polymer matrix.

Detection of liquefied petroleum gas below lowest explosion limit (LEL) using nanostructured hexagonal strontium ferrite thin film

The nano crystalline hexagonal strontium ferrite nanoparticles SrFe12O19 were synthesized successfully by chemical co-precipitation method. Thin films of strontium ferrite were prepared on glass substrate and characterized by various techniques such as XRD, SEM, TEM, EDS, UV-spectroscopy and FTIR. XRD pattern revealed the phase transformation of M-type hexa-ferrite with the minimum crystallite size of 18nm. Uniform macroporous surface structure of the film was exposed by SEM images. Existence of iron, strontium and oxygen in the material was confirmed by EDX. Optical characterization of the material was done by UV-Spectroscopy and band gap was found as 3.2eV. The liquefied petroleum gas (LPG) sensing behavior of strontium ferrite film was investigated at room temperature. The variations in electrical resistance of the film were measured with the exposure of LPG with respect to time as a function of concentration (0.5–5vol.%) of LPG. The maximum value of sensitivity for these films was found 7 and maximum sensor response was 602.23.

Synthesis, characterization and microwave characteristics of ternary nanocomposite of MWCNTs/doped Sr-hexaferrite/PANI

Substituted strontium ferrite (sub-SF) nanoparticles are prepared by a sol-gel method and added to functionalized multiwalled carbon nanotubes (MWCNTs). The ternary nanocomposite of MWCNTs/sub-SF/polyaniline (PANI) is prepared by in-situ polymerization of aniline on MWCNTs/sub-SF reaction mixture. The morphology, structure and magnetic properties of the nanocomposites are investigated by SEM, XRD, FTIR and VSM, respectively. The microwave characteristics are measured using a vector network analyzer. The XRD patterns exhibit representative diffraction peaks corresponding to hexagonal structure, and the structure of the MWCNTs is not distorted. SEM micrographs show that sub-SF nanoparticles and PANI chains are uniformly dispersed on the surface of MWCNTs. The MWCNTs/sub-SF/PANI exhibit a minimum reflection loss of −26dB at 10GHz with 3GHz bandwidth and a matching thickness of 5mm. This excellent microwave characteristic indicates the synergistic effect of the three components to enhance the impedance matching and improve the microwave absorption properties of the composite.

Synthesis, Characterization, and Microwave Absorption Properties of Reduced Graphene Oxide/Strontium Ferrite/Polyaniline Nanocomposites.

Strontium ferrite nanoparticles were prepared by a coprecipitation method, and reduced graphene oxide/strontium ferrite/polyaniline (R-GO/SF/PANI) ternary nanocomposites were prepared by in situ polymerization method. The morphology, structure, and magnetic properties of the ternary nanocomposites were investigated by X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), TEM, Raman, and VSM. The microwave-absorbing properties of the composites were measured by a vector network analyzer. The XRD patterns show the single phase of strontium hexaferrite without other intermediate phases. TEM photographs reveal that strontium ferrite nanoparticles are uniformly dispersed on the surfaces of R-GO sheets. The R-GO/SF/PANI nanocomposite exhibited the best absorption property with the optimum matching thickness of 1.5 mm in the frequency of 2–18 GHz. The value of the maximum RL was −45.00 dB at 16.08 GHz with the 5.48-GHz bandwidth. The excellent absorption properties of R-GO/SF/PANI nanocomposites indicated their great potential as microwave-absorbing materials.

Conducting, magnetic polyaniline/Ba0.25Sr0.75 Fe11(Ni0.5Mn0.5)O19 nanocomposite: Fabrication, characterization and application

In this contribution, Ni/Mn doped Barium Strontium Ferrite nanoparticles (Ba0.25Sr0.75Fe11(Ni0.5Mn0.5)O19) and conducting polyaniline/Ba0.25Sr0.75Fe11(Ni0.5Mn0.5)O19 nanocomposite were fabricated successfully through sol–gel method and in-situ polymerization technique, respectively. Field emission scanning electron microscope (FESEM), Energy-dispersive X-ray spectroscopy analysis (EDX), X-ray powder diffraction (XRD), Mössbauer spectroscopic measurements and Fourier transform infrared spectroscope (FT-IR) analyses were adopted to confirm the composition, morphology and structure of materials. The obtained results revealed the formation of hexagonal M-type rod-shape ferrite with average particle size of about 45 nm (according to XRD data, using Debye–Scherre formula). The saturation magnetization of ferrite nanoparticles and PANI/Ferrite nanocomposite reported 44.03 and 9.85 emu/g, respectively, using vibrant sample magnetometer (VSM). Standard four-point-probe technique was employed to measure the conductivity of samples. Also optical characteristic of samples was examined by means of UV–Vis and Diffuse Reflectance Spectra (DRS) techniques which proved the formation of conducting coating of emeraldine on the surface of magnetic nanoparticles. Also the UV–vis studies indicated that the ferrite nanoparticles have an optical band gap of 1.8 eV while the values of 1.65 and 2.66 eV obtained for PANI/Ferrite nanocomposite. Finally, the microwave absorption properties of prepared nanoferrite and nanocomposite at different thicknesses (2, 3 and 4 mm) were determined at the X-band (8–12 GHz) using vector network analyzer (VNA). In this study, minimum reflection loss of −21.68 dB and maximum available bandwidth of 4.8 GHz were obtained for PANI/Ferrite (20 wt% ferrite) at the frequency of 10.6 GHz. The results suggested the fabricated nanocomposite could be a suitable candidate for decreasing radar signature.

Strontium ferrite nanoparticle study: Thermal decomposition synthesis, characterization, and optical and magnetic properties

Monoferrite strontium ferrite nanoparticles were successfully synthesized in the presence of strontium oxalate, [(SrC2O4)], as strontium precursor by using solid-state thermal decomposition method. X-ray diffraction study was used to determine phase purity, crystal structure, and average crystallite size of the strontium ferrite nanoparticles. The electrical conductivity measurement of the sintered sample was carried out at 300°C. Metal nitrates and oxalate precursor without any solvent or surfactant were used in this method; later, they were decomposed at 850°C for 2h in a gas mixture of 85% Ar and 15% H2. The average diameter of the strontium ferrite nanoparticles was 40nm. The as-prepared strontium ferrite nanoparticles were characterized extensively by techniques like XRD, transmission electron microscope (TEM), high-resolution TEM (HRTEM), scanning electron microscopy (SEM), Fourier transform infrared (FT-IR), vibrating sample magnetometer (VSM), room temperature photoluminescence (Pl), ultraviolet–visible spectroscopy (UV–vis), and energy dispersive spectrometry (EDS).

Influence of multiwalled carbon nanotube addition on the magnetic and reflection-loss characteristics of Mn–Sn–Ti substituted strontium ferrite nanoparticles

In this work, Mn–Sn–Ti substituted strontium ferrite (Sr-ferrite:SrM) nanoparticles were attached on the outer surface of varied multi-walled carbon nanotubes volume fraction with the amount of 10, 15, 20, 25 and 30, by employing of the sol–gel method. The phase identification and morphologies of the nanocomposites were characterized by X-ray diffraction and field emission scanning microscopy respectively. The obtained results showed that the single phase SrFe9.5 (Mn1.25Sn0.625Ti0.625) O19 nanoparticles were decorated on MWCNTs can be obtained at 900°C. Fourier transform infrared revealed that both the stretching and the bending modes are formed in the citrate complex in the ferrite and hydroxyl and carboxyl groups on the external surface of MWCNTs. The Magnetic properties were measured by a vibrating sample magnetometer. It was found that saturation magnetization, remanent magnetization and coercivity decrease by an increase in the MWCNTs content from 10 to 30vol%. The reflection loss measurement of the prepared absorber which contain the ratio of 70–30mass% for the nanocomposite to the polyvinyl chloride, done by the vector network analyzer, proved that the prepared nanocomposites have the maximum reflection loss of −28dB at the frequency of 8.8GHz for Mn–Ti–Sn substituted strontium ferrite −30vol% MWCNT nanocomposite with a bandwidth of 4GHz (RL>−10dB).

Evaluation of microwave and magnetic properties of substituted SrFe12O19 and substituted SrFe12O19/multi-walled carbon nanotubes nanocomposites

SrFe12−xCrx/2Alx/2O19 (x = 0–2.5) nanoparticles and ferrite/multi-walled carbon nanotubes (MWCNTs) nanocomposites were synthesized by a sol–gel method. The XRD patterns show a relatively weak peak around 26° which is corresponding to the graphite (002) lattice plane of the MWCNTs. The peak of Fourier transform infrared spectroscopy (FTIR) at 1729 cm−1 can be assigned to CO bond of carboxylic groups, indicating the presence of poly(acrylic acid) (PAA) chains in PAA–carbon nanotubes. Field emission scanning electron microscopy (FE-SEM) micrographs demonstrate that strontium ferrite nanoparticles are strung along the MWCNTs. Transmission electron microscopy (TEM) was employed to study the structure of MWCNTs. Vibrating sample magnetometer (VSM) measurements show that with an increase in x content, the values of saturation of magnetization of SrFe12−xCrx/2Alx/2O19 nanoparticles reduce, while coercivity increases. Results of reflection loss indicate that with adding Cr–Al cations and MWCNTs to strontium ferrite; it is possible to cover a wideband of electromagnetic waves in the frequency range of 50–74 and 12–18 GHz. In addition, it can be seen that the strontium ferrite nanoparticles and nanocomposites display a great potential application as wideband electromagnetic wave absorbers.