Vibrating Sample Magnetometer Techniques Research Articles

Preparation of Fe3O4/HAp nanoparticles from eggshells with highly adsorption capacity for methylene blue

Multifunctional materials have become one of the most interesting research subjects in recent years. Hydroxylapatite (HAp) coating on the surface of iron oxide (Fe3O4) nanoparticles allow to obtain material with adsorbable and magnetic properties. This study aims to salvage recycled eggshell to successfully produce adsorbent nanoparticles and evaluate treatment ability of methylene blue (MB) dyes in water. The magnetic nanomaterial was synthesized by a simple and inexpensive method. The X-ray diffraction technique was employed to characterize the structure of nanoparticles. The as-synthesized nanoparticles were analyzed by Fourier transform infrared spectroscopy technique to determine the presence of functional groups and bonds in the molecule. The surface morphology of as-synthesized Fe3O4/HAp nanoparticles was studied by transmission electron microscopy. The magnetic properties of Fe3O4 nanoparticles and Fe3O4/HAp nanoparticles were evaluated by vibrating sample magnetometer technique. The typical synthesized-HAp were dispersed rod-like particles with about 10 nm in width and 50 nm in length, the other part of final material was dispersed in spherical shape and their magnetism was 16.2 emu.g-1. The adsorption of MB was conducted with 89.6% yield at pH 8.

CoFe2O4@Methylcellulose/AC as a New, Green, and Eco-friendly Nano-magnetic adsorbent for removal of Reactive Red 198 from aqueous solution

• Methylcellulose (MC) was played an essential role to improve the nanomagnetic adsorbent structure for the Reactive Red 198 (RR198) adsorption. • CoFe 2 O 4 @MC/AC was synthesized as a novel nanomagnetic adsorbent with a facile, simple, and green microwave-assisted coprecipitation method. • The physical and chemical structure of CoFe 2 O 4 @MC/AC were approved with FTIR, FESEM, EDS, Mapping, Line Scan, XRD, VSM, and BET techniques. • The isotherm, kinetic and thermodynamic of RR198 adsorption were investigated. • CoFe 2 O 4 @MC/AC exhibited good chemical stability and reusability. Methylcellulose (MC) is the most common commercial cellulose ether and the most attractive biopolymer due to its cheap cost of biodegradability, biocompatibility, hydrophilicity, and lack of toxicity. In this study, CoFe 2 O 4 @MC/activated carbon (AC) was synthesized as a unique magnetic nano-adsorbent in the presence of MC biopolymer for Reactive Red 198 (RR198) dye removal. The nano-magnetic adsorbent was characterized by FESEM (Field emission scanning electron microscopy), EDS (Energy-dispersive X-ray spectroscopy), Mapping, Linescan, BET (Brunauer–Emmett–Teller), FTIR (Fourier Transform Infrared Spectroscopy), XRD (X-Ray Diffraction), and VSM (Vibrating-Sample magnetometer). For simple separation by external magnetic fields, the Ms value was 57.91 emu/g. According to XRD analysis, the nano-adsorbent maintains its crystal structure, with an average crystal size of 11 nm. The maximum removal efficiencies of RR198 for synthetic and real wastewater samples under optimal conditions (an initial concentration of 10 mg/L, pH 3, contact time of 10 min, nanocomposite dose of 1.5 g/L, and a temperature of 25 °C) were 92.2% and 78%, respectively. The adsorption experiments were fitted well with the Freundlich isotherm (R 2 = 0.989) and pseudo -second-order kinetic (R 2 = 0.995). The values of entropy changes (ΔS = 35.087 kJ/mol.k), enthalpy changes (ΔH = -9.862 kJ/mol), and negative Gibbs free energy changes (ΔG) showed that the adsorption process was exothermic. Finally, the reusability findings showed that after six recovery cycles, the efficiency decreased slightly (90.1%). In the end, it can be concluded that the prepared CoFe 2 O 4 @Methylcellulose/AC can be used as an efficient adsorbent for the removal of RR198 from an aqueous solution.

Preparation of magnetic molecularly imprinted polymer based on multiwalled carbon nanotubes for selective dispersive micro-solid phase extraction of fenitrothion followed by ion mobility spectrometry analysis.

A novel molecularly imprinted polymer based on magnetic multiwalled carbon nanotubes was fabricated and applied for selective dispersive micro-solid phase extraction of fenitrothion prior its determination by ion mobility spectrometry. The composite was synthesized using magnetic multiwalled carbon nanotubes as the support. Methacrylic acid was used as the functional monomer, fenitrothion as the template, ethylene glycol dimethacrylate as the cross-linker, and 2,2-azoisobutyronitrile as the initiator. The resultant polymer was characterized by FTIR spectroscopy, X-ray diffraction, field emission scanning electron microscopy, Brunauer-Emmet-Teller analysis, thermogravimetric analysis, and vibrating sample magnetometer techniques. Experimental factors affecting the extraction efficiency such as pH and amount of sorbent were evaluated. Under optimum experimental conditions, the developed method displayed the linear range of 5-220 μg/L with a detection limit of 1.3 μg/L. The intra- and interday relative standard deviations for determination of fenitrothion were 3.6 and 4.7% (n=6), respectively. Ultimately, the proposed method was used to monitor trace amounts of fenitrothion in fruits, vegetables, and water samples.

Magnetic interaction between soft and hard ferrimagnetic phases in BaFe12O19 + CuFe2O4 composite

Magnetic behavior of (with x = 1, 2, and 4) has been explored. These composites were prepared by the standard sol-gel route. X-ray diffraction, Field Emission Scanning Electron Microscopy, and Transmission Electron Microscopy techniques were employed to characterize the composites. The magnetic interaction between and particles in the composite has been studied by recording the M–H hysteresis loops by employing the Vibrating Sample Magnetometer technique. The role of copper ferrite in the composite has been explored. It is interesting to note that the (i.e. x =1) composite shows the maximum magnetic parameters (M s , H c , and (BH) max) among all the composite samples under study. Hence, this composition has been investigated extensively by annealing at different temperatures to optimize its magnetic properties. The + composite annealed at 1000 oC exhibits the maximum energy product (BH) max and saturation magnetization (M s ). The magnetic interaction between two different magnetic phases in the composite has been explored by using the Henkel plot study with the help of isothermal remanent magnetization (IRM) and direct current demagnetization (DCD) M–H curves. The exchange coupling between soft and hard magnetic phases in the composite is also examined by the derivative of magnetization with the magnetic field.

Influence of Ce3+ on the Structural, Morphological, Magnetic, Photocatalytic and Antibacterial Properties of Spinel MnFe2O4 Nanocrystallites Prepared by the Combustion Route

The present work describes the effect of Ce3+ ion doping on the structural, morphological, and magnetic properties of spinel manganese ferrite (MnFe2O4) nanocrystallites (NCs) using various instrument techniques. Rare earth element (REE) Cerium (Ce3+) doped MnFe2O4 NCs were prepared by a simple microwave combustion technique. In the present scenario, ferrites are widely used for photocatalytic dye degradation and antibacterial applications. Aiming to achieve this, we prepared Ce3+ doped MnFe2O4 NCs by microwave combustion method and urea as burning agent and the obtained powder samples were characterized by powder X-ray diffraction (XRD), Fourier transform infrared (FT-IR), high resolution scanning electron microscope (HR-SEM), high resolution transmission electron microscope (HR-TEM) and vibration sample magnetometer (VSM) techniques. The pure spinel phase formation was confirmed by XRD analysis. FTIR spectra show two prominent absorption bands under 1000 cm−1, which confirms the formation of the spinel structure. HR-SEM and HR-TEM pictures demonstrated a sphere-shaped morphology and also expose the combination and agglomeration of grains, which are mostly due to the magnetic characteristics of the samples. The magnetic properties of the synthesized MnCexFe2−xO4 (x = 0.0, 0.1, 0.3, and 0.5) NCs were studied by VSM analysis at room temperature (RT) shows ferromagnetic behavior. The photodegradation results showed that MnFe2O4 and Ce doped MnFe2O4 NCs have a higher potential to degrade methylene blue (MB) and the sample MnCe0.3Fe1.7O4 NCs showed superb photocatalytic performance (91.53%) compared to other samples. The antibacterial activities of Gram-positive S. aureus, B. subtilis and Gram-negative K. pneumonia and E. coli were investigated using pure and Ce3+ substituted MnFe2O4 NCs and a higher activity for MnCe0.3Fe1.7O4 NCs than other samples was observed, which indicated that they can be used in biomedical applications.

Analysis of electromagnetic properties of Ce–Zn substituted barium hexaferrite for electronic circuit applications

Electromagnetic properties of Ce–Zn substituted barium hexaferrite (Ba0.5Ce0.5ZnFe11O19 ferrite) synthesized using ceramic technique were analyzed in detail in the X band frequencies to describe its response to microwave absorber and microwave electronic device applications. The phase formations, structural morphology, polarization mechanisms and magnetic properties for Ba0.5Ce0.5ZnFe11O19 ferrite, which provide important information about electrical load transmission mechanism were analyzed using X-ray diffraction, scanning electron microscopy, two-port vector network analyser and vibrating sample magnetometer techniques, respectively. The experimental complex dielectric plane plots (Cole-Cole plots) of the Ba0.5Ce0.5ZnFe11O19 ferrite represent an equivalent RC circuit corresponding to the impedance circuit in the Smith Chart. The reflection loss increased to the highest value (−17.04 dB) depending on the amount of Ce in the structure of the Ba0.5Ce0.5ZnFe11O19 ferrite and the bandwidth, which is important for microwave absorbers, increases.

Microwave assisted hydrothermally synthesized cobalt doped zinc ferrites nanoparticles for the degradation of organic dyes and antimicrobial applications

A novel photocatalyst based cobalt doped zinc ferrites nanoparticles (Co–ZnFe2O4 NPs) was prepared to actively concentrate degradation of organic dyes in water. The aim this study is to investigate the effect of substitution of Co2+ for Zn2+ in zinc ferrites nanoparticles and is characterized with UV–visible spectroscopy, XRD, TEM, SEM, Photoluminescence and Vibrating sample magnetometer technique. When the calcinations temperature increases from 150 °C to 450 °C the amorphous ferrites begins to vanish and the characteristic reflections of cubic spinal Co–ZnFe2O4 phase are only observed at 450 °C. The band gap energy (Eg) of sample calcined at 250 °C is calculated at 5.2 eV and that of 450 °C is 4.5 eV. The observed value of band gap energy decreased with increasing calcinations temperature in the samples. The increase in PL peak intensity is due to collective emissions and light-scattering. The doping material, cobalt substitution at spinel zinc ferrites surface, and hence gradually decrease the amorphous effect, increase the saturation magnetization and decrease the coercivity while increasing the temperature. The compounds calcined at 250 °C and 450 °C were investigated for their in vitro antimicrobial activity against Staphylococcus aureus. A sample with 450 °C calcination temperature leads to higher efficiencies in the inhibition of growth of bacteria and degradation of organic dyes. Hence, this study provides a novel photocatalyst of Co–ZnFe2O4 NPs in the tile to degrade and analyze the environmentally ignored organic compounds.

Synthesis of (Gly) 3 PMo 12 O 40 @ MnFe 2 O 4 organic/inorganic hybrid nanocomposite as an efficient and magnetically recoverable catalyst for oxidative desulfurization of liquid fuels

Here, we report on the preparation and characterization of a new organic/inorganic hybrid nanocomposite comprised of the glycine-modified polyoxomolybdate (abbreviated as (Gly)3PMo12O40) and manganese ferrite (MnFe2O4) nanoparticles. The hybrid nanocomposite was successfully synthesized under mild ultrasound irradiation and characterized by powder X-ray diffraction, Fourier transform infrared spectroscopy, field emission scanning electron microscope, energy dispersive X-ray, and vibrating sample magnetometer techniques. To explore the (Gly)3PMo12O40@MnFe2O4 applicability, it was used in catalytic oxidative desulfurization (Cat-ODS) reactions. The experimental results revealed excellent catalytic activity of the hybrid nanocomposite in the removal of hazardous organosulfur compounds from model fuel oils (MFOs) and typical real gasoline. The sulfur removal from MFOs could reach up to 95% at the operating temperature of 35°C, the ambient pressure, and the contact time of 1 hour. Quite surprisingly, the total sulfur content of real gasoline was lowered from 0.4985 to 0.0198 wt% under the same reaction conditions. In addition, the (Gly)3PMo12O40@MnFe2O4 presented a brilliant magnetically reusability with slight diminution after seven consecutive Cat-ODS cycles. These results encourage the further exploration of the application of (Gly)3PMo12O40@MnFe2O4 organic/inorganic hybrid nanocomposite in the production of clean diesel and jet fuels.

Significance of thermal interfacing in hematite (α-Fe2O3) nanoparticles synthesized by sol-gel method and its characteristics properties

Hematite (α-Fe2O3) nanoparticles were synthesized through the cost-effective sol-gel method. The impact of temperature influenced in as-prepared and calcinated hematite nanoparticles was explored. To characterize the synthesized compounds with the help of X-ray diffraction (XRD), Thermogravimetric & Differential Thermogravimetric Analysis (TG-TDA), Fourier Transform Infrared spectroscopy (FT-IR), Ultra-Violet spectroscopy (UV-Vis), Scanning Electron Microscope with Energy Dispersive X-ray Analysis (SEM with EDAX), and Vibrating Sample Magnetometer techniques (VSM). The structural studies were confirmed rhombohedral structure with space group R-3c in C-2 NPs. The surface morphological analysis confirmed shape, size, and particle homogeneity were ensured with the arrival of temperature. The thermal analysis reported as the C-1 NPs shows excellent phase stability till reaching 1100 °C. FT-IR confirms the phase purity of the nanoparticles synthesized. The optical absorption at 534nm confirms the formation of red color α-Fe2O3 C-2 NPs and the optical bandgap values 1.92–1.97eV. The magnetometry steady was observed as a magnetic transition of paramagnetic to weak ferromagnetic magnetic behavior of NPs, which implies that several structural improvements are achieved by the thermal interfacing on the NPs surface.

Polymeric Fe<sub>3</sub>O<sub>4</sub> Conjugates with Bioactive Plant Molecules: Platforms for Antimicrobial Therapy

The emerging nano biosystems are competent in diagnosis, drug delivery, and monitoring of therapeutic response. Both imaging and therapeutic functions can be achieved by using nanoplatforms. These nanoplatforms promise to revolutionize the medical management of many personalized illnesses. The well-developed surface chemistry of iron oxide (Fe3O4) makes it easy to charge them with pharmaceutics, promoting them as nanoplatforms for building up nanoparticle-based drug delivery systems. The strategy to design multifunctional Fe3O4 conjugates with bioactive molecules of plant origin to show enhanced activity is reported here. The conjugation reveals the magnetic Fe3O4 core nanoparticle surface readily link to hydroxyl sites of the Dextrin molecule, which further conjugate to conjugated with Curcumin and D-Limonene, which are powerful anti-cancer, anti-inflammatory, and antioxidant agents. The structural, morphological, optical, and magnetic properties were analyzed by X-ray diffraction, FT-Infrared, HR-Tunneling Electron Microscopy, and Vibrating Sample Magnetometer techniques. The potential drug loading was measured as Drug Entrapment Efficiency using UV-Vis spectroscopy. The antibacterial property was tested on the bacterium S. aureus and E. coli. Fe3O4-Dextrin nanoconjugates proved to be efficient for loading and stabilizing Curcumin and Limonene. Thus, multifunctional Fe3O4 conjugates are explored as exciting nano-drug carriers for targeted drug delivery.

Structural and magnetic investigation of Cr3+ substitution on Zn–Co ferro-spinel nanoparticles

Herein, the work aims at providing an insight to the effect of Cr3+ ion substitution on structural and magnetic properties of nanocrystalline zinc doped cobalt ferrite nanoparticles. The formation of single phase Cr substituted Zn–Co (Zn0.5Co0.5CrxFe2−xO4) nanoparticles consisting of Fd3̄m space group with crystallite size ranging from 37 to 45 nm is confirmed by X-ray Diffraction. The cation distribution calculated using Reitvield refinement confirmed that Cr3+ ion prefers the octahedral site. The desired stoichiometric ratio of the elements is confirmed using Energy dispersive X-ray analysis. The Infra Red spectra unveiled the presence of two absorption bands i.e. tetrahedral and octahedral bands, associated with spinel ferrites. The magnetic behaviour of Cr substituted Zn–Co system with the increment in Cr concentration is analyzed using Vibrating sample magnetometer technique and is further pursued using Mossbauer spectroscopy. The correlation between cation distribution and magnetic behaviour of the system is also discussed in detail.

Preparation of regenerable magnetic nanoparticles for cellulase immobilization: Improvement of enzymatic activity and stability.

To obtain regenerable magnetic nanoparticles, triethoxy(3-isocyanatopropyl)silane and iminodiacetic acid (IZ) were used as the starting material and immobilized on Fe3 O4 nanoparticles. Copper ions (Cu2+ ions) were loaded on the Fe-IZ nanoparticles and used for cellulase immobilization. The support was characterized by spectroscopic methods (FTIR, NMR) and thermogravimetric analysis, transmission electron microscopy, scanning electron microscope, X-ray diffraction, energy dispersive X-ray analysis, and vibrating sample magnetometer techniques. As a result of experiments, the amount of protein bound to immobilized cellulase (Fe-IZ-Cu-E) and cellulase activity was found to be 33.1mg/g and 154 U/g at pH5, 50°C, for 3h. The results indicated that the free cellulase had kept only 50% of its activity after 2h, while the Fe-IZ-Cu-E was observed to be around 77%, at 60°C. It was found that the immobilized cellulase maintained 93% of its initial catalytic activity after its sixth use. Furthermore, the Fe-IZ-Cu-E retained about 75% of its initial activity after 28 days of storage. To reuse the support material (Fe-IZ-Cu), it was regenerated by thorough washing with ammonia or imidazole.

Proper pH value enhances giant magneto-impedance effect of FINEMET/rGO composite ribbons by electroless plating

Electromagnetic interaction in composite structure materials has been a crucial physical mechanism to optimize magnetic property of magnetic devices. In this paper, the composite ribbons of FINEMET coated with reduced graphene oxide (rGO) were successfully prepared by electroless plating method at different pH values. The structure, morphology and magnetic properties of the FINEMET/rGO composite ribbons were characterized by X-Ray diffraction, Raman spectroscopy, scanning electron microscope, giant magneto-impedance (GMI) analysis and vibrating sample magnetometer techniques, respectively. The resultsshowed that the peak position field of composite ribbon first decreases and then increases with the variation of pH value, which indicated that there may be existed electromagnetic interaction and stress between rGO and the FINEMET ribbon. The electromagnetic interaction may lead to the redistribution of current density and the change of skin depth. An interpretation in terms of electromagnetic interaction between rGO and FINEMET ribbon was proposed, which provided a new perspective for analyzing the variation in GMI effect of composite materials.

Synthesis of a magnetic sorbent and its application in extraction of different pesticides from water, fruit, and vegetable samples prior to their determination by gas chromatography-tandem mass spectrometry

In this investigation, an efficient sorbent based on Fe3O4@polyphenols magnetic nanoparticles has been prepared using the extract of Mentha piperita leaves for the first time. The main purposes of this study were synthesis of economically affordable and environmentally friendly sorbent using the extract of Mentha piperita leaves and evaluating its application as a sorbent in magnetic solid phase extraction. The functional groups, magnetic property, size, and shape of the synthesized sorbent were characterized. The sorbent was utilized for the extraction and preconcentration of various pesticides (chlorpyrifos, fenazaquin, penconazole, diniconazole, oxadiazon, haloxyfop-methyl, hexaconazole, clodinafop-propargyl, tebuconazole, and fenoxaprop-p-ethyl) from vegetable, fruit, and water samples. After magnetic solid phase extraction, a dispersive liquid–liquid microextraction method was done to achieve low detection limits. The enriched pesticides were monitored by gas chromatography-tandem mass spectrometry. The synthesized sorbent was characterized by Fourier transform infrared, scanning electron microscopy, energy-dispersive x-ray spectroscopy, x-ray diffraction, and vibrating sample magnetometer techniques, which confirmed the successful synthesis of the magnetic nanoparticles. The effective parameters such as the sorbent weight, ionic strength, pH, vortex time, and kind and volume of elution and extraction solvents were studied. Under optimum extraction conditions, the method showed broad linear ranges (0.05–1000 µg L-1) with low limits of detection (0.27–4.13 ng L-1) and quantification (0.91–13.8 ng L-1). Extraction recoveries and enrichment factors were in the ranges of 54–89 % and 491–811, respectively.

Studies on characterization, magnetic and electrochemical properties of nano-size pure and mixed ternary transition metal ferrites prepared by the auto-combustion method

Abstract

Design, preparation, and characterization of Fe3O4 nanoparticles encapsulating β‐cyclodextrin‐bearing guanidine as a highly efficient and reusable heterogeneous base catalyst for synthesis of 3,4‐dihydropyrano[3,2‐c]chromenes

Chromene substructure is an important structural motif present in a variety of medicines, natural products, and materials showing biological activities. Here, a simple and convenient procedure for the synthesis of 3,4‐dihydropyrano[3,2‐c]chromene derivatives is described. For this purpose, Fe3O4 nanoparticles supported on β‐cyclodextrin‐guanidine were successfully prepared and used as catalyst. The structure of this catalyst was assigned by Fourier transform infrared spectroscopy, X‐ray diffraction, scanning electron microscopy, thermal gravimetric analysis, and vibrating sample magnetometer techniques. The prepared nanocomposites were used as a highly active, heterogeneous, and reusable nanocatalyst for the one‐pot, three‐component reaction of 4‐hydroxycoumarin, aromatic aldehydes, and ethyl cyanoacetate. This method has advantages such as mild conditions, high yields, easy workup and simple purification of products, little catalyst loading, cost efficiency, and reusability of the catalyst.

Novel magnetic propylsulfonic acid-anchored isocyanurate-based periodic mesoporous organosilica (Iron oxide@PMO-ICS-PrSO3H) as a highly efficient and reusable nanoreactor for the sustainable synthesis of imidazopyrimidine derivatives

In this study, preparation and characterization of a new magnetic propylsulfonic acid-anchored isocyanurate bridging periodic mesoporous organosilica (Iron oxide@PMO-ICS-PrSO3H) is described. The iron oxide@PMO-ICS-PrSO3H nanomaterials were characterized by Fourier transform infrared spectroscopy, energy-dispersive X-ray spectroscopy and field emission scanning electron microscopy as well as thermogravimetric analysis, N2 adsorption–desorption isotherms and vibrating sample magnetometer techniques. Indeed, the new obtained materials are the first example of the magnetic thermally stable isocyanurate-based mesoporous organosilica solid acid. Furthermore, the catalytic activity of the Iron oxide@PMO-ICS-PrSO3H nanomaterials, as a novel and highly efficient recoverable nanoreactor, was investigated for the sustainable heteroannulation synthesis of imidazopyrimidine derivatives through the Traube–Schwarz multicomponent reaction of 2-aminobenzoimidazole, C‒H acids and diverse aromatic aldehydes. The advantages of this green protocol are low catalyst loading, high to quantitative yields, short reaction times and the catalyst recyclability for at least four consecutive runs.

Surface-sensitive magnetic characterization technique for ultrathin ferromagnetic film with perpendicular magnetic anisotropy

Ultrathin ferromagnetic films display a wealth of spectacular characteristics, one of which is that two-dimensional ferromagnetism is stabilized exclusively by magnetic anisotropies. In this work, we experimentally demonstrated the realization of ultrathin yttrium iron garnet (Y3Fe5O12) films with perpendicular magnetic anisotropy by pulsed laser deposition. A labyrinthine magnetic domain configuration in Y3Fe5O12 was identified by magnetic force microscopy, qualitatively determining that the magnetic moment possesses an out-of-plane component. Magnetic moments in the Y3Fe5O12 film were investigated by using a vibrating sample magnetometer and magnetic circular dichroism spectroscopy. Due to the surface sensitivity, the characterization technique based on magnetic circular dichroism spectroscopy presents as a high-resolution magneto-optical method to determine the magnetic property quantitatively, which has an advantage over the vibrating sample magnetometer technique commonly used for bulk crystals or powders, especially when the paramagnetic background from the supporting substrate is non-negligible. Our work introduces the burgeoning material synthesis and processing technology, and miscellaneous characterization techniques into the study of conventional magnetic oxide films, providing powerful supplements to the detection and modulation of magnetism at the nanoscale.

Magnetic and photocatalytic properties of Ni–Co ferrites

In this work, different compositions of NixCo1-xFe2O4 (x = 0, 0.2, 0.5, 0.8 and 1) spinel ferrites were prepared through the chemical co-precipitation technique by substitution of Co ions with Ni ions. Thermogravimetric analysis, differential thermal analysis, X-ray diffraction, transmission electron microscopy, scanning electron microscopy, Fourier transform infra-red, Raman spectroscopy, ultraviolet–visible, photoluminescence and vibrating sample magnetometer techniques were used to characterize the synthesized compounds. The obtained NixCo1-xFe2O4 nanoparticles with the average size in the range of ~17–~36 nm have single cubic structure. The crystal size and lattice parameter increase with the increase in nickel content. There are two major absorption bands on the FT-IR spectra: the high frequency bands ‘ν1’ is assigned to the tetrahedral while the low frequency bands ‘ν2’ is assigned to the octahedral complex. The nanoferrites have an optical band gap between 1.37 and 1.78 eV. The magnetic property such as saturation magnetization and coercivity of the compounds remarkably changes with the concentration of Ni2+. The photocatalytic activity of the compounds was further studied using methylene blue (MB) as model organic pollutants. It is found that an appropriate amount of nickel (Ni2+) can greatly increase the amount of hydroxyl radicals generated by the nanoferrite, leading to an obvious increase in the photocatalytic activity.

Impact of rare earth europium (RE-Eu3+) ions substitution on microstructural, optical and magnetic properties of CoFe2−xEuxO4 nanosystems

In this study, pure cobalt ferrite (CoFe2O4) nanoparticles and europium doped CoFe2O4 (CoFe2−xEuxO4; x = 0.1, 0.2, 0.3) nanoparticles were synthesized by the precipitation and hydrothermal approach. The impact of replacing trivalent iron (Fe3+) ions by trivalent rare earth europium (RE-Eu3+) ions on the microstructure, optical and magnetic properties of the produced CoFe2O4 nanoparticles was studied. X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectra exposed the consistency of a single cubic phase with the evidence of Eu2O3 phases for x ≥ 0.2. FTIR transmittance spectra showed that, the all investigated samples have three characteristic metal-oxygen bond vibrations corresponding to octahedral B-site (υ1 and υ2) and tetrahedral A-site (υ3) around 415 cm−1, 470 cm−1 and 600 cm−1 respectively. XRD and energy dispersive X-ray spectroscopy studies affirmed the integration of RE-Eu3+ ions within CoFe2O4 host lattice and decrease of average crystals size from 13.7 nm to 4.7 nm. Transmission electron microscopy (TEM) analysis showed the crucial role played by RE-Eu3+ added to CoFe2O4 in reducing the particle size below 5 nm in agreement with XRD analysis. High resolution-TEM (HR-TEM) analysis showed that the as-synthesized spinel ferrite, i.e., CoFe2−xEuxO4, nanoparticles are single-crystalline with no visible defects. In addition, the HR-TEM results showed that pure and doped CoFe2O4 have well-resolved lattice fringes and their interplanar spacings matches that obtained by XRD analysis. Magnetic properties investigated by the vibrating sample magnetometer technique illustrated transformation of magnetic state from ferromagnetic to superparamagnetic at 300 K resulting in introducing RE-Eu3+ in CoFe2O4 lattice. At low temperature (~5 K) the magnetic order was ferromagnetic for both pure and doped CoFe2O4 samples. Substitution of Fe3+ ions in CoFe2O4 nanoparticles with RE-Eu3+ ions optimizes the sample nanocrystals size, cation distribution and magnetic properties for many applications.