Vibrating Sample Magnetometer Research Articles

Fluorescent superparamagnetic magnetite-silica nanocomposites as carriers of a platinum diimine complex for photodynamic therapy.

Novel fluorescent superparamagnetic nanocomposites have been fabricated by introduction of the coumarin group on the surface of amine-functionalized magnetite-silica nanocomposites, and characterized by X-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy, fluorescence spectra, dynamic light scattering and vibrating sample magnetometer techniques. The nanocomposites were employed as delivery vehicles of a photoactive platinum diimine complex. The cellular uptake and photocytotoxicity of the photosensitizer-loaded nanocomposites in HeLa cells (human cervical cancer line) or HL-7702 cells (human liver cell line) have been studied by fluorescence spectra and cell viability assay, respectively. The results suggest that the nanocomposites can be used to monitor the cellular uptake of the photosensitizer, and can significantly enhance the photocytotoxicity of the photosensitizer towards cancer cells when employed as carriers of the photosensitizer. Also, the photosensitizer-loaded nanocomposites are almost nontoxic to human normal cells either in the dark or after irradiation.

Boosting nickel nanoferrite’s specific capacitance with Azadirachta Indica for advanced supercapacitors

Nickel Ferrite (NiFe2O4) a valuable transition metal oxide possessing a spinel structure, it is extensively utilized in industry due to its compelling properties. In this present study the sol–gel auto-combustion synthesis method was employed using nitrates and citric acid in conjunction with double distilled water (DDW) and Azadirachta Indica extract. The X-ray diffraction (XRD) analysis revealed the formation of a cubic spinel phase with high crystallinity. Crystallite size of prepared Nickel Ferrite in double distilled water and Azadirachta Indica by Scherrer’s equation and Williamson-Hall plot (W-H) are 28.09 nm and 33.01 nm as well as 16.23 nm and 16.55 nm, with microstrains of 0.32739 % and 0.339 × 10−3 % respectively. The notable reduction in the crystallite size is observed when employing Azadirachta Indica compared to the double distilled water-based synthesis. The X-ray density of the synthesized sample in double distilled water and Azadirachta Indica are obtained as 3.935 (g cm−3) and 5.427 (g cm−3). Transmission electron microscopy (TEM) of Azadirachta Indica-based nanostructured Nickel Ferrite material exhibited a particle size of 17.06 nm. The study encompassed the calculation of various parameters such as hopping lengths, polaron radius, specific surface area, packing fraction, and dislocation density. Magnetic parameters are comprehensively examined using a vibrating sample magnetometer (VSM), revealing a Bohr magneton is 3.278. The shifting of coercivity curve observed towards right due to exchange bias effect and the unidirectional anisotropy for diamagnetic Azadirachta Indica based Nickel ferrite. Optical properties are investigated through UV–VIS and Fourier-transform infrared (FTIR) spectroscopy, resulting in a band gap energy of 1.75 eV and a porosity is 11.16 %. Electrochemical evaluation of Nickel Ferrite electrodes is conducted over a potential range from 0.0 to 1 V. The specific capacitance of Nickel Ferrite electrodes synthesized with double distilled water and Azadirachta Indica are determined as 511.9 F/g and 695 F/g respectively, at a scan rate of 50 mV/s, as evaluated through cyclic voltammetry (CV) measurements in Ag/AgCl (0.1 M NaOH as electrolyte). The specific capacitance of Nickel Ferrite, produced with double distilled water and Azadirachta Indica extract, is 686 F/g and 817.398 F/g respectively, as determined by Galvanostatic charge–discharge (GCD) measurements. The study conclusively demonstrated significantly improvement in the electrochemical performance of Nickel Ferrite, synthesized with Azadirachta Indica extract for supercapacitor application. Based on GCD and CV, the specific capacitance has been boosted significantly with Azadirachta Indica extract for supercapacitor application.

Investigation of Electromagnetic Wave Absorption Properties of Ni-Co and MWCNT Nanocomposites.

In recent years, severe electromagnetic interference among electronic devices has been caused by the unprecedented growth of communication systems. Therefore, microwave absorbing materials are required to relieve these problems by absorbing the unwanted microwave. In the design of microwave absorbers, magnetic nanomaterials have to be used as fine particles dispersed in an insulating matrix. Besides the intrinsic properties of these materials, the structure and morphology are also crucial to the microwave absorption performance of the composite. In this study, Ni-Co- MWCNT composites were synthesized, and the changes in electric permittivity, magnetic permeability, and reflectance loss of the samples were evaluated at frequencies of 2 to 18 GHz. Nickel-Cobalt-Multi Wall Carbon Nanotubes (MWCNT) composites were successfully synthesized by the co-precipitation chemical method. The structural, morphological, and magnetic properties of the samples were characterized and investigated by X-ray diffractometer (XRD), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Vibrating Sample Magnetometer (VSM), and Vector Network Analyzer (VNA). The results revealed that the Ni-Co-MWCNT composite has the highest electromagnetic wave absorption rate with a reflectance loss of -70.22 dB at a frequency of 10.12 GHz with a thickness of 1.8 mm. The adequate absorption bandwidth (RL <-10 dB) was 6.9 GHz at the high-frequency region, exhibiting excellent microwave absorbing properties as a good microwave absorber patent. Based on this study, it can be argued that the Ni-Co-MWCNT composite can be a good candidate for making light absorbers of radar waves at frequencies 2- 18 GHz.

Reduced Graphene Oxide Loaded with ZCF Magnetic Nanoparticles as a Promising Photocatalyst and Antibacterial Agent

Due to waste, pollution, and unequal distribution of the world’s finite freshwater resources, there is currently a problem of water scarcity. Therefore, developing novel, affordable, and efficient techniques for water purification is essential. Here, the photo-assisted degradation of Methyl Orange dye (MO) under visible light and UV was achieved by using reduced graphene oxide (RGO) photocatalyst loaded with Zn0.5Cu0.5Fe2O4 (ZCF) called MRGO 20. Furthermore, all prepared samples were characterized by X-ray diffraction (XRD), fourier transformation infrared (FTIR), transmission electron microscope (TEM), vibrating sample magnetometer (VSM) and Raman analysis. After 40 minutes, the high photocatalytic efficacy effectively eliminated about 96 % of the 10 ppm MO using 20 mg of MRGO 20 NPs at pH 5 under Visible light irradiation. From the results, MRGO 20 demonstrated good performance stability after five cycles of photocatalytic degradation of MO dye. The shown performance of the generated samples in both visible and UV light may motivate further investigation into more potent photocatalysts for water filtering. MRGO 20 NPs nanocomposite displayed great activity against Gram-negative (E. coli) bacteria with a zone of inhibition (ZOI) mm value of 24.0 mm, and high biofilm inhibition of 94.3%. The produced samples’ observed efficacy in both UV and visible light may encourage continued research into more effective photocatalysts for the filtration of water and for biological applications.

Doxorubicin-loaded core@shell cobalt ferrite-barium titanate magnetoelectric nanofibers for improved anticancer activity.

Conventional drug delivery systems often suffer from non-specific distribution and limited therapeutic efficacy, leading to significant side effects. To address these challenges, we developed magnetoelectric, cobalt ferrite@barium titanate (CFO@BTO) nanofibers, with a core-shell structure for targeted anticancer drug delivery. The electrospinning method was employed to synthesize polymeric nanofibers based on magnetoelectric core-shell nanostructures. The Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), X-ray diffraction (XRD) and Vibrating sample magnetometer (VSM) analysis confirmed the successful loading of nanostructures on polymeric nanofiber, the core-shell morphology and magnetoelectric phase of cobalt ferrite@barium titanate CFO@BTO, respectively. To verify the drug attachment, the optimization of drug release in an applied external magnetic field, and the time required for control drug release, UV-Vis spectroscopy was used. The effectiveness of magnetic field-assisted controlled drug release was demonstrated by achieving a 95 ± 1.03% drug release from magnetoelectric nanofibers (MENFs) within 30 minutes under a magnetic field of 4mT. In vitro cytotoxicity assay on human skin cancer (SK-MEL-28) cell lines exhibited a maximum 90 ± 2% cytotoxicity with 2±0.03 cm of drug loaded MENFs. Furthermore, the Hemolysis assay was carried out to affirm the biocompatibility and non-toxicity of drug loaded MENFs, which is suitable for anticancer therapy.

Study of the poly (butylene adipate-co-terephthalate)/poly (vinyl alcohol) coated recycled Fe3O4 magnetic particle carriers for immobilization penicillin G acylase

In this work, the process began by coating a layer of poly (butylene adipate-co-terephthalate) (PBAT)/poly (vinyl alcohol) (PVA) on the surface of magnetic Fe3O4 particles (MPs) obtained from the nickel slag. Then, it was grafted by glutaraldehyde (GA) to obtain Fe3O4@PBAT/PVA-g-GA MPs, which were used as a carrier. Finally, the immobilized PGA was achieved by forming a covalent bond through the Schiff base reaction. To confirm each stage, employed Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), vibration sample magnetometer (VSM), scanning electron microscope-energy spectroscopy of dispersive x-rays (SEM-EDS), inductively coupled plasma mass spectrometry (ICP-MS), and x-ray photoelectron spectrophotometry (XPS). The immobilization conditions were studied and optimized to improve immobilized PGA stability and catalytic activity. The immobilization of PGA demonstrated its optimal performance under the process conditions. The results were achieved using a 2.5 vol.% enzyme solution concentration, a pH of 8.0, an immobilization time of 24 h, and an immobilization temperature of 37 °C. Under these conditions, the immobilized PGA exhibited an enzyme activity recovery (EAR) of 93.71%, an enzyme activity (EA) of 31,367 U/g, and an enzyme loading capacity (ELC) of 111 mg/g. The operating stability, reusability, and storage stability of Fe3O4@PBAT/PVA-g-GA-PGA MPs were investigated. Comparatively, immobilized PGA exhibited superior operational and storage stability compared to free PGA. Even after 11 repeated uses, the immobilized PGA retained 58% of its initial activity, while the carrier recovery (Re) reached 82%. This indicated that the immobilized PGA MPs offer improved longevity and efficiency, making them a promising choice for practical applications.

Fabrication of Aspergillus oryzae lipase-immobilized magnetic Cu3(PO4)2∙3H2O nanoflowers for efficient synthesis of structured phospholipids

To synthesize structured phospholipids (SPLs) in an efficient and green manner is of great significance. Herein, novel Fe3O4@SiO2-Aspergillus oryzae lipase (AOL)/copper phosphate trihydrate nanoflowers (FLCNs) were prepared by coprecipitation method and then characterized by energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, and vibrating sample magnetometer etc. FLCN activity was further evaluated by promoting functional medium-chain SPL (MCSPL) or short-chain SPL (SCSPL) synthesis via biotransesterification between soybean lecithins and medium-chain fatty acids (MCFAs) or short-chain fatty acids (SCFAs) under optimal reaction conditions. Moreover, FLCNs and free AOLs were comparatively assayed in enzymatic properties. As a result, FLCNs were successfully fabricated with sufficiently large surfaces and numerous enzyme active sites. Owing to these structural features, after reacting at 40 °C for 36 h with FLCN dosage of 6% and substrate mass ratio of 1:3:3, FLCNs exhibited much more excellent activity in MCSPL synthesis with 88.30 ± 0.63% of MCFA incorporation than benchmark enzymes and heterogeneous functional materials. Most significantly, in the first biosynthesis of functional SCSPLs facilitated by FLCNs, much superior SCFA incorporation of 66.55 ± 0.73% was obtained. Notably, FLCNs also possessed convenient magnetic separability together with superior pH and temperature tolerances, thermal and storage stabilities, and recyclability to free AOLs. In brief, the present investigation provides a new biological strategy for effective, economic, convenient, and eco-friendly SPL synthesis in food and pharmaceutical industries, highlighting its merits in functional lipid production.

Biosynthesis; Characterization; and Antibacterial, Antioxidant, and Docking Potentials of Doped Silver Nanoparticles Synthesized from Pine Needle Leaf Extract

The current study focused on the synthesis of doped silver nanoparticles (doped AgNPs) with yttrium (Y), gadolinium (Gd), and chromium (Cr) from pine needle leaf extract (PNLE). X-ray diffraction (XRD) was performed to assess the phase formation, detecting 61.83% from Ag and 38.17% for secondary phases of AgCl, AgO, Y, Cr-, and Gd phases. The size and shape of the NPs were determined by transmission electron microscopy (TEM), showing a spherical shape with an average particle size of 26.43 nm. X-ray photoelectron spectroscopy (XPS) detected the oxidation state of the presented elements. The scanning electron microscope (SEM) and the energy-dispersive X-ray analysis (EDX) determined the morphology and elemental composition of the NPs, respectively. Fourier transform infrared spectroscopy (FTIR) determined the different functional groups indicating the presence of Ag, Y, Gd, Cr, and other groups. Photoluminescence (PL) spectroscopy showed the optical properties of the NPs. A vibrating sample magnetometer (VSM) revealed the ferromagnetic behavior of the doped AgNPs. The antibacterial activity of the doped AgNPs was tested against six uro-pathogenic bacteria (Staphylococcus aureus, Staphylococcus haemolyticus, Enterococcus faecalis, Escherichia coli, Klebsiella pneumonia, and Pseudomonas aeruginosa) using the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) microdilution assays, agar well diffusion assay, time–kill test, and antibiofilm screening assays, revealing significant activity, with MICs ranging between 0.0625 and 0.5 mg/mL and antibiofilm activity between 40 and 85%. The antioxidant activity was determined by the 1,1, diphenyl 1-2 picrylhydrazyl (DPPH) radical scavenging assay with a potential of 61.3%. The docking studies showed that the doped AgNPs had the potential to predict the inhibition of crucial enzymes such as penicillin-binding proteins, LasR-binding proteins, carbapenemase, DNA gyrase, and dihydropteroate synthase. The results suggest that the doped AgNPs can be applied in different medical domains.

Microstructural and Magnetic Characteristics of High-Entropy FeCoNiMnTi Alloy Produced via Mechanical Alloying

In the current study, X-ray diffraction, scanning electron microscopy, and vibrating sample magnetometer techniques were used to examine the impact of milling time on the microstructural and magnetic characteristics of Fe30Co20Ni20Mn20Ti10 (at%) produced via mechanical alloying. Results demonstrate that phase change is dependent on up to 30 h of milling. In terms of the hcp-Fe2Ti intermetallic and the BCC-FeCoNiMnTi supersaturated solid solution, the system maintains its two-phase structure at higher times. Additionally, the final average crystallite size was estimated to be approximately 10 nm, and the lattice strain was found to be between 0.95 and 1.15 %. As a function of milling time, the magnetic properties are discussed with the microstructural and crystallographic alterations. The collected powder after 100 h of milling has an Ms value of 28 emu/g and a Hc value of 25 Am−1, which is consistent with exceptional soft magnetics. This is essentially due to the Fe2Ti intermetallic and the BCC-Fe-based solid solution production, together with the refinement of the crystallite size. Furthermore, the presence of paramagnetic Ti atoms in solid solution and the development of high densities of defects and interfaces have been connected to the low value of Ms.

Fe3O4@SiO2-NH2 Functionalized Nanoparticles as a Potential Contrast Agent in Magnetic Resonance

The present work proposes a method for the synthesis of a nanoparticle with a superparamagnetic Fe3O4 core coated with SiO2-NH2 by ultrasound-assisted coprecipitation. Additionally, the nanoparticle is functionalized with a microinflammation biomarker peptide, and its effects on the viability of monkey kidney endothelial cells and the Vero cell line were evaluated. The main physicochemical properties of the nanoparticles were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), a vibrating sample magnetometer (VSM), a field emission scanning electron, Scanning Electron Microscopy (SEM), and High-Resolution Transmission Electron Microscopy (HR-TEM). The results showed that the nanoparticles are spherical, with sizes smaller than 10 nm, with high thermal stability and superparamagnetic properties. They also demonstrated cell viability rates exceeding 85% through Magnetic Resonance Imaging (MRI). The results indicate the potential of these nanoparticles to be used as a contrast agent in magnetic resonance to detect mild brain lesions.

Photocatalytic degradation of Rhodamine B using a reusable and magnetically separable Fe3O4/rGO/ZnO nanocomposite synthesized through green approach utilizing plant leaf extracts

We propose the magnetically separable, green synthesis of Fe3O4/rGO/ZnO using a higher mass ratio of Fe3O4/rGO and varying ZnO concentration to degrade an aqueous solution of Rhodamin B under Fenton reaction and UV light irradiation. Fe3O4 had been synthesized under the coprecipitation method utilizing Moringa oleifera leaf, while rGO had been fabricated by sonicating GO utilizing Amaranthus viridis leaf. Afterward, Fe3O4/rGO was composited under a facile method with a mass ratio of 5:5. And the last, Fe3O4/rGO/ZnO was green-synthesized through precipitation method using Amaranthus viridis leaf with various molarity ratio of Fe3O4/rGO: ZnO equal to 1:1, 1:2, 1:3, 1:4, and 1:5. X-ray diffraction revealed the presence of Fe3O4 and ZnO phases, while Raman spectroscopy confirmed the successful reduction of GO to rGO. The morphological analysis demonstrated that the particles were nearly spherical, nonuniform, and slightly dispersed, with some agglomeration observed on the rGO sheets. Fourier-transform infrared spectroscopy identified metallic functional groups, including Fe–O and Zn–O, at 524–570 cm−1 and 447–462 cm−1, respectively. However, redshift absorption and band gap narrowing were observed as the ZnO concentration increased. Photoluminescence analysis revealed that increased ZnO concentration reduces recombination and improves charge separation efficiency. The vibrating sample magnetometer exhibited soft magnetic properties. The magnetization of Fe3O4/rGO saturated at 21.7 emu/g and diminished as incorporated ZnO. The photodegradation increased with the increase of ZnO concentration, reaching its optimum at 1:5, about 89.9%. Fe3O4/rGO/ZnO demonstrates a possible ecologically friendly photocatalyst for wastewater remediation. The photocatalyst can be reused for up to three cycles with no significant change in its performance. Scavenger evaluation indicates that electrons and holes are the predominant reactive species in the photocatalytic reaction involving Fe₃O₄/rGO/ZnO.

Study on the Properties and Mechanism of m‐FACs/f‐Fe3O4/Epoxy Wear‐Resistant Magnetic Coating

ABSTRACTIn view of the wear problem of key parts of magnetic fluid seal device, epoxy resin (EP) composite coatings reinforced with Fe3O4 and fly ash cenospheres (FACs) were fabricated successfully. The structural and morphological features of the fillers and the composite coatings were characterized by Fourier transform infrared and scanning electron microscopy. CFT‐I material surface performance comprehensive tester was used to investigate the tribological behaviors of the as‐prepared composite coatings. Vibrating sample magnetometer was used to investigate the coatings' magnetic property. The formation mechanism of the composite coating was analyzed by the infrared spectrum results combined with molecular dynamics simulations. The results demonstrated that adding a certain amount of double fillers will have a synergistic effect, and its mechanical properties are better than those of single fillers. The tribological property of the m‐FACs/f‐Fe3O4/EP composite coatings was optimal under magnetic fluid friction, which is about an order of magnitude lower than the wear rate under dry friction. The saturation magnetization of the m‐FACs/f‐Fe3O4/EP composite coating is 2.77 emu/g, and the magnetic susceptibility reaches 4.64 × 10−4 m3/kg. Therefore, the m‐FACs/f‐Fe3O4/EP composite coating will be expected to solve the wear problem of equipment components in complex environments of magnetic field and friction.

Preparation, Purification, and Hydrophilization of Magnetic-Carbon Nanofibers

This study aims to synthesize, purify, and modify magnetic carbon nanofibers (Mag-CNF) into hydrophilic carbon material. The synthesis method was carried out by chemical vapor deposition (CVD) using the catalyst from Incolloy at 800°C with argon, nitrogen, hydrogen, and acetylene gases. The purification of Mag-CNF was then conducted by dissolving Mag-CNF with toluene and ethanol, followed by vacuum annealing. The hydrophilization of Mag-CNF was further performed by adding amine groups via reacting Mag-CNF with ethylene diamine, NaNO2, and H2SO4. The successfully prepared Mag-CNF has characteristics of tubular tube bundles consisting of carbon nanofibers with an average diameter of 100-120 nm. The X-ray diffraction (XRD) profile shows the characteristics of carbon, iron, iron oxide, and iron carbide. The Raman spectra show the existence of D, G, and G' bands corresponding to the characteristics of carbon nanomaterials. The magnetic property characterization using a vibration sample magnetometer (VSM) shows the synthesized product as ferrimagnetic materials. The modification results show the addition of hydrophilic groups to Mag-CNF, such as O–H and N–H groups, as analyzed in Fourier Transform Infrared (FTIR) spectra. The successful hydrophilization was also visually confirmed using a dispersion test in water, showing that Mag-CNF has better dispersion after surface modification.

Application of a magnetic graphene nanocomposite modified with 5-aminoisophthalic acid amine group for chromium (VI) adsorption from aqueous solutions: kinetic and thermodynamic studies

ABSTRACT Polymer nanocomposites are composite materials that incorporate nanomaterials, such as magnetic graphene oxide (mGO), into a polymer matrix. To enhance its adsorption capacity, the surface of mGO nanoparticles was polymerised by a 5-aminoisophthalic acid amine group (mGO-AIPA) through a simplified co-precipitation method. The structural and morphological characteristics of the synthesised nanoparticles were evaluated through techniques such as X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), Field emission scanning electron microscopy (FESEM), Thermogravimetric analysis (TGA), and Vibrating sample magnetometer (VSM). Response surface method (RSM) was used to evaluate the effectiveness of mGO-AIPA nanocomposite in removing chromium (VI) ions by examining variables such as solution of pH, contact time, adsorbent dose and initial concentration. Also, the study of kinetic models, adsorption isotherms and thermodynamic modelling of the process were evaluated. The results found that the mGO-AIPA nanocomposite has the maximum removal of chromium (VI) ions from the aqueous solution by 83.11% in optimal conditions including pH 3.5, contact time of 35 min, an adsorbent dosage of 25 mg g−1 and an initial concentration of 55 mg L−1. The pseudo-second-order kinetic and Langmuir isotherm models had a better fit with the experimental data of adsorption and the maximum adsorption capacity of chromium (VI) the base of the Langmuir model was 90.91 mg g−1. Moreover, the thermodynamic analysis indicated that the process was exothermic and nonspontaneous process, implying that it was energetically unfavourable. These findings suggest that the mGO-AIPA nanocomposite has a high performance as an effectual adsorbent to eliminate chromium heavy metal from an aqueous medium.

Microwave-induced enhancements in the structural, optical, dielectric, and magnetic properties of Er2O3/MgO nanocomposites

Erbium-trioxide (Er2O3) and magnesium oxide (MgO) nanocomposite were effectively synthesized in the form of crystalline powder using a microwave irradiation approach. Various techniques were employed for identifying crystalline structure, FTIR fingerprint region, fluorescence emission behaviors, and surface morphology, dielectric, and magnetic properties using PXRD, FTIR spectroscopy technique, fluorescence spectroscopic technique, SEM analysis, frequency vs. dielectric constant, and MH curve analysis, respectively. Confirmation of the metal-oxygen bond such as Er2O3, and MgO was established through the analysis of stretching frequencies in the FTIR spectrum. The PXRD results using Rietveld refinement confirmed the crystalline nature of the synthesized nanoparticles, consisting of Er2O3, and MgO with unit cell compositions ~ 94.12 and ~ 5.88%, respectively. SEM imaging provided insights into the morphology of the particles, revealing a spherical shape with noticeable agglomeration. The elemental compositions such as Erbium (Er) and Oxygen (O), were validated by the EDS spectrum, confirming the successful achievement of Er2O3, and MgO nanoparticle in the synthesized composite. In addition, the vibrating sample magnetometer (VSM) graph illustrated the paramagnetic behavior of the doped Er2O3/MgO composite at room temperature. The thorough examination of the synthesized Er-MgO NPs, covering structural, morphological, and magnetic characteristics, contributes to a comprehensive understanding of their properties.

Synthesis and Characterization of Cu-Co Substituted Strontium Hexaferrite for Magnetic Applications

In this study, the structural and magnetic characterizations of a series of SrCoxCuxFe12-2xO19; 0.0 ≤ x ≤ 0.5 samples, which were produced by the conventional ceramic method, were carried out. The structure was examined by X-ray diffraction (XRD) technique and optical microscopy. A vibrating sample magnetometer (VSM) was used to characterize the ferrimagnetic properties. XRD patterns confirmed the presence of a single phase as Sr-hexaferrite while there were not any peaks of unreacted Fe2O3 phase. The densities varied between 92 – 98 %. XRD patterns of the Sr-hexaferrite samples were slightly modified because of the co-substitution of Cu-Co; however, the magnetic properties changed remarkably. The sample with Cu-Co of x = 0.1 content had the highest saturation magnetization (33.52 emu/g), remanence (19.74 emu/g), and coercivity (4.3 kOe). The synthesized magnetic samples were found to be suitable for the development of attractive ferrimagnetic properties for the current ferrite magnets.

Supported phenylalanine on core-shell mesoporous microsphere as a catalyst for the synthesis of triazolo[1,2-a] indazole-triones and spiro triazolo[1,2-a] indazole-tetraones

In recent years, mesoporous silica materials have gained attention due to their unique properties, such as high surface area, pore volume, size, and chemical stability. These characteristics make them effective in various fields, particularly efficient supports in heterogeneous catalytic reactions. The present study developed a novel type of core-shell mesoporous microsphere material by anchoring phenylalanine on a core-shell SiO2@NiO@MS support. The catalyst support (SiO2@NiO@MS) was synthesized through homogeneous precipitation and sol-gel methods, with NiO encapsulated within the porous silica. The catalyst was characterized using various techniques, including Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), Scanning electron microscopy (SEM), Energy dispersive spectroscopy (EDS), Elemental mapping analysis, N2 adsorption-desorption, Transmission electron microscopy (TEM), Vibrating sample magnetometer (VSM), and Thermogravimetric analysis (TGA). It was then employed for the synthesis of triazolo[1,2-a]indazole-trione and spiro triazolo[1,2-a]indazole-tetraones compounds from 4-phenyl urazole, dimedone, and aromatic aldehydes or isatin derivatives. This synthetic approach offers multiple advantages, including high yields, faster reaction times, low catalyst requirements, and environmentally sustainable conditions.

Insights into the structure and magnetic characteristics of Ho substituted Ca-Cu based Ca0.5Cu0.5Fe12-xHoxO19 hexaferrites nanoparticles

This work demonstrates a systematic attempt to explore the structure and magnetic properties of Ho3+ substituted Ca-Cu hexaferrite nanocrystals. Ca0.5Cu0.5Fe12-xHoxO19 (x = 0.00, 0.05, 0.10, 0.15, 0.20) M−type hexaferrites are synthesized via sol–gel auto combustion technique. XRD spectra is used to evaluate the phase, and substituent-induced modifications of crystallites. The lattice parameters ‘a’ and ‘c’ lies in the range (5.887–5.898) Å and (23.184–23.195) Å. The size of crystallites ranges from 55.73 to 59.41 nm. The specimen’s morphology indicates the consistent distribution of grains with Ho substitution. The coercivity of samples increased slightly from 2.85 to 3.15 kOe, as determined by vibrating sample magnetometer (VSM) loops, whereas saturation magnetization increased from 26.41 to 30.13 emu/g. The discussion also encompasses variations in anisotropy field (Ha), anisotropy parameter (B), magneto-crystalline anisotropic constant (K), and magnetic moment per formula unit mB(µB) and their effect on main magnetic parameters.

Dielectric and magnetic properties of microwave-absorbing FeAlxOy catalysts fabricated via solution combustion synthesis

Iron-based alumina (FeAlxOy) nanocomposites are microwave-absorbers and catalysts, which makes them promising for emerging microwave-assisted thermocatalytic technologies. Solution combustion synthesis (SCS) has been used to synthesize FeAlxOy powders, and prior work has demonstrated that adjusting SCS parameters significantly changes phase composition and specific surface area of the products. However, it is unclear how synthesis parameters affect their microwave-absorbing properties, which are essential for optimizing microwave-assisted technologies. To address this challenge, in the present work, twelve different FeAlxOy products were synthesized at different combinations of the SCS parameters such as two fuels (citric acid and glycine), two heating modes (hotplate and muffle furnace), and three Fe:Al molar ratios (2:1, 1:1, 1:2). Dielectric and magnetic properties of the products were characterized using a network analyzer and a vibrating sample magnetometer. Based on the measured permittivity and permeability, penetration depth and reflection loss were calculated as a function of frequency and bed thickness. The products were heated by microwaves at 2.45 GHz and then examined with X-ray diffraction (XRD) analysis. For all products, the magnetic saturation was lower than for bulk iron oxides because of the small crystallite size and aluminum substitution. The use of glycine induced high dielectric losses and enabled fast microwave-heating rates compared to citric acid. Higher Fe:Al ratio also led to higher dielectric and magnetic losses. With glycine fuel, SCS in a furnace induced larger penetration depth and lower microwave absorption than SCS on a hotplate. The minimization of reflected power was more sensitive to the thickness of the product bed than to the frequency of the electromagnetic field. Post-heating XRD analysis revealed different phase transformations in the FeAlxOy powders depending on the SCS parameters. An FeAlxOy material, synthesized via incipient wetness impregnation, lacked magnetic losses and did not heat well as compared to the SCS products.

Machine learning assisted design and preparation of Fe85Si2B8.5P3.5C1 amorphous/nanocrystalline alloy with high Bs and low Hc

Four machine learning (ML) models including eXtreme Gradient boosting (XGBT), k-Nearest Neighbor (kNN), Gradient Boosting Decision Tree (GBDT) and Artificial Neural Network (ANN) were employed to predict saturation flux density (Bs), coercivity (Hc), grain size, magnetostriction (λ), and Curie temperature (Tc) of Fe-based amorphous/nanocrystalline alloys. To maximize predictive ability of ML models, grid-search and normalization were used to search the most proper parameters of ML and pre-process raw data, respectively. XGBT had best predictive and generalization ability for predicting Bs and Hc with coefficient of determination (R2) of 0.992 and 0.967, respectively. Based on the feature importance analysis from the XGBT model, the Fe85Si2B8.5P3.5C1 amorphous alloy ribbon with good magnetic properties, such as high Bs, low Hc, was designed and prepared by melt spinning. X-ray diffraction (XRD), differential scanning calorimetry (DSC), transmission electron microscopy (TEM), vibrating sample magnetometer (VSM), B–H loop tracer, and magnetostriction instrument were used to identify the phase structure and physical properties of the Fe85Si2B8.5P3.5C1 alloy. It was found that the Fe85Si2B8.5P3.5C1 alloy had good magnetic properties with Bs of 1.82 T and the Hc of 2.02 A/m after annealing at 723 K for 180 s, in good agreement with the designed results by machine learning.