Nano-sized Ferrites Research Articles

Green sonochemical synthesis and fabrication of cubic MnFe2O4 electrocatalyst decorated carbon nitride nanohybrid for neurotransmitter detection in serum samples

The binary nanomaterials and graphitic carbon based hybrid has been developed as an important porous nanomaterial for fabricating electrode with applications in non-enzymatic (bio) sensors. We report a fast synthesis of bimetal oxide particles of nano-sized manganese ferrite (MnFe2O4) decorated on graphitic carbon nitride (GCN) via a high-intensity ultrasonic irradiation method for C (30 kHz and 70 W/cm2). The nanocomposites were analyzed by powder X-ray diffraction, XPS, EDS, TEM to ascertain the effects of synthesis parameters on structure, and morphology. The MnFe2O4/GCN modified electrode demonstrated superior electrocatalytic activity toward the neurotransmitter (5-hydroxytryptamine) detection with a high peak intensity at +0.21 V. The appealing application of the MnFe2O4/GCN/GCE as neurotransmitter sensors is presented and a possible sensing mechanism is analyzed. The constructed electrochemical sensor for the detection of 5-hydroxytryptamine (STN) showed a wide working range (0.1–522.6 μM), high sensitivity (19.377 μA μM−1 cm−2), and nano-molar detection limit (3.1 nM). Moreover, it is worth noting that the MnFe2O4/GCN not only enhanced activity and also promoted the electron transfer rate towards STN detection. The proposed sensor was analyzed for its real-time applications to the detection of STN in rat brain serum, and human blood serum in good satisfactory results was obtained. The results showed promising reproducibility, repeatability, and high stability for neurotransmitter detection in biological samples.

Strong correlation between Dy3+ concentration, structure, magnetic and microwave properties of the [Ni0.5Co0.5](DyxFe2-x)O4 nanosized ferrites

The dysprosium ions (Dy3+)-substituted nanosized ferrites (NFs) of composition [Ni0.5Co0.5](DyxFe2-x)O4 (x ≤0.08) were prepared using the citrate gel process. To analyse the magnetic properties of the samples, the Mössbauer spectroscopy methods and vibrating sample magnetometry (VSM) were applied. The room temperature Mössbauer spectra were fitted to determine the hyperfine parameters of the proposed NFs. The preferential occupation of the octahedral B sites by the Dy3+ in the spinel ferrite sublattice was confirmed from the cations distribution. The hyperfine magnetic field of both sublattice decreased whereas the increase in the Dy3+ substitution was observed. The S-parameters of the prepared NFs in the high frequency range were measured by the co-axial method. In addition, the MW reflection losses were evaluated by means of the frequency-dependent (in the range of 1–20GHz) complex permittivity and permeability spectra. All the NFs indicated that the absorption of the electromagnetic radiation was ranging between 2.9–5.5GHz due to the natural ferromagnetic resonance. A correlation amongst the Dy3+ concentration, microstructure, magnetic and microwave (MW) characteristics of these NFs was established. It’s been asserted that by controlling the Dy3+ contents carefully, the MW absorption and magnetic attributes of the proposed spinel NFs can be tailored.

NADİR TOPRAK KATKISININ SPİNEL FERRİTLERİN MANYETİK ÖZELLİKLERİNE ETKİSİ

Nano-size ferrites (NSF) are magnetic nanoparticles (MNPs) which have attracted great interest in the last decades owing to their high surface area-to-volume ratio, high saturation magnetization, initial permeability, etc. Nickel-copper-zinc ferrites are especially used in multi-layer chip inductors (MLCIs) which are found in mobile phones, camcorders, notebook computers, etc. MLCIs are composed of alternating layers of silver electrodes and soft ferrites. Thus, it is important to develop magnetic characteristics in ferrites for requiring less ferrite layers and hence to obtain further miniaturized devices. The goal of our study is to investigate the effect of rare earth substitution of Ni-Cu-Zn ferrite nanoparticles. Ni-Cu-Zn NSFs substituted with rare earth metal (RE) ions Eu3+, Tb3+, and Dy3+ in varying concentrations were obtained by a sonochemical method. We investigated the crystal structure, chemical bonding, morphology and magnetic characteristics of the Ni-Cu-Zn NSFs by X-ray powder diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and vibrating sample magnetometry (VSM), respectively. The phase purity of the samples was confirmed by the XRD analysis. Stretching vibrations of spinel ferrites were verified by the FT-IR analysis. VSM results reveal that the rare earth substitution has a significant effect on the magnetic properties of the Ni-Cu-Zn NSFs.

Protective and Suppressing Electromagnetic Interference Properties of Epoxy Coatings Containing Nano-Sized NiZn Ferrites

Nano-crystalline ferrites with the chemical formula NixZn(1-x)Fe2O4, where x=0, 0.2, 0.4, 0.6, 0.8, 1.0, were synthesized using a co-precipitation method. The obtained ferrites were investigated by X-ray diffraction (XRD). The corrosion inhibiting behavior of nano-sized ferrites was tested using carbon steel samples and 10% aqueous ferrite extracts. Results were compared with previous data obtained for micro-sized ceramic ferrites. Nanoparticles show more favourable properties regarding inhibiting corrosion processes on steel. 2mm thick epoxy coatings on steel containing 10% vol. of nano-sized ferrites has been investigated as a microwave absorber. The microwave reflectivity of the coating was measured within the range from 6.5 to 15 GHz. Both the nano- and micro-sized ferrites included in the coatings exhibited different reflection loss spectra. The greatest attenuation on a level of 8-16 dB was observed. The nano-ferrite-filled epoxy coating exhibited a higher minimum reflection frequency in comparison with the micro-ferrite-filled coating. A frequency shift of 1-2 GHz was observed.

Praseodymium ferrite nano-particles based modified electrode and its application in determination of dopamine

The present works report the graphite based electrochemical sensor modified by nano-sized praseodymium ferrite (np-PrFeO3) materials for the detection of dopamine. The combustion technique was used to synthesize these nanomaterials of np-PrFeO3 using praseodymium oxide and ferric nitrate as precursor materials. The nanomaterials were characterized by field emission scanning electron microscopy and transmission electron microscopy techniques. The crystallite sizes of synthesized nanoparticles (nps) were in the range from 40-45 nm with cubic crystal system. Cyclic voltammetry and Differential pulse voltammetry techniques were used to study the electrochemical property and were observed to be superior to earlier reports. The limit of detection of dopamine at PrFeO3/GP electrode was 600 nM with 5 to 200 µM for linearity range. The phosphate buffer solution of pH 6.0 was used for all experimental work with maintaining the scan rate 100mVs-1 and 50mVs-1 for cyclic voltammetry and Differential pulse voltammetry, respectively.

Delamination strategy to achieve Ti3C2Tx/CNZF composites with tunable electromagnetic absorption

Delamination of the multiple layers in 2D MXenes is still a crucial challenge because this process generates single-layer nanosheets and extends specific surface area, which makes MXenes promising substrate to carry matters and endow them with enhanced dielectric loss. In present work, novel multilayered composites of Co0.2Ni0.4Zn0.4Fe2O4 nanoparticles (CNZF) attached to MXenes (Ti3C2Tx/CNZF) with various compositions were synthesized by hydrothermal process. Owing to the nano-sized ferrites that are helpful for the delamination of layered structure and improved anisotropic energy, the multiple scattering and dielectric loss of Ti3C2Tx/CNZF are greatly boosted. Hence, the Ti3C2Tx/CNZF composites showcased a prominent microwave attenuation property, with a minimum reflection loss value of −58.4 dB at 6.2 GHz. Simultaneously, the effective bandwidth is at lower frequency region of 3.8–6.0 GHz associated with an absorber thickness of 4.2 mm. The present work provides a strategy to construct novel 2D absorbing materials by allowing ultrasmall magnetic nanoparticles to decorate on the interlayers of hierarchical structure.

Nano-Size Hexagonal Ferrites for Microwave and Millimeter-Wave Devices

Complex dielectric and magnetic properties of micro- and nano-size hexagonal ferrites have been studied. Two different measurement techniques have been applied to characterize the samples in the broad frequency range from 1.7 to 120 GHz. It was observed that the constitutive material properties, namely permittivity and permeability, as well as the ferromagnetic resonance frequency of the samples vary with the change in particle dimensions. Based on the results of these measurements, a model for calculating the ferromagnetic resonance frequency of ferrite powders has been derived, which takes into account the size and shape of the particles in the sample. It can be concluded from the size-dependent absorption properties observed in this study that these materials are considered to be tunable millimeter-wave absorbers.

Enhancement of Viscoelastic and Electrical Properties of Magnetorheological Elastomers with Nanosized Ni-Mg Cobalt-Ferrites as Fillers.

Carbon-based particles, such as graphite and graphene, have been widely used as a filler in magnetorheological elastomer (MRE) fabrication in order to obtain electrical properties of the material. However, these kinds of fillers normally require a very high concentration of particles to enhance the conductivity property. Therefore, in this study, the nanosized Ni-Mg cobalt ferrite is introduced as a filler to soften MRE and, at the same time, improve magnetic, rheological, and conductivity properties. Three types of MRE samples without and with different compositions of Mg, namely Co0.5Ni0.2Mg0.3Fe2O4 (A1) and Co0.5Ni0.1Mg0.4Fe2O4 (A2), are fabricated. The characterization related to the micrograph, magnetic, and rheological properties of the MRE samples are analyzed using scanning electron microscopy (SEM), vibrating sample magnetometer (VSM), and the rheometer. Meanwhile, the effect of the nanosized Ni-Mg cobalt ferrites on the electrical resistance property is investigated and compared with the different Mg compositions. It is shown that the storage modulus of the MRE sample with the nanosized Ni-Mg cobalt ferrites is 43% higher than that of the MRE sample without the nanomaterials. In addition, it is demonstrated that MREs with the nanosized Ni-Mg cobalt ferrites exhibit relatively low electrical resistance at the on-state as compared to the off-state condition, because MRE with a higher Mg composition shows lower electrical resistance when higher current flow occurs through the materials. This salient property of the proposed MRE can be effectively and potentially used as an actuator to control the viscoelastic property of the magnetic field or sensors to measure the strain of the flexible structures by the electrical resistance signal.

Structural, microwave permittivity, and complex impedance studies of cation (Cr, Bi, Al, In) substituted SrNi-X hexagonal nano-sized ferrites

Sr2Ni2TxFe28-xO46 (T = Cr3+, Bi3+, Al3+, In3+; x = 0.25) hexa-ferrites were fabricated via the sol-gel route. The phase temperature, which was obtained using thermo-gravimetric analysis (TGA), reveals that the X-type hexagonal phase of these materials is highly stable above 1200 °C. The phase formation was confirmed using X-ray diffraction (XRD) patterns. The variation in lattice strain shows the significant effect of substituted cations on the structure of the materials. The crystallite size of these materials was found in the range of 18–19 nm. The increase in dielectric constant, as well as with moderate loss, was observed in all substituted samples between 0.001 GHz and 1 GHz. The large values of dielectric constant were observed for Al3+ and In3+ substituted materials at higher frequency. The values of slope (n) reveal that all the materials exhibit frequency dependent ac conductivity. The Cole-Cole plots show the single semicircle for all samples. These semicircles of the Cole-Cole plots indicate that resistance inside the material is due to grains and grain boundaries. The both grain and grain boundaries resistance inside the material may cause large values of dielectric constant as well as the losses in the material. The large values of dielectric constant and impedance with moderate dielectric losses of these materials reflect their significant role in the fabrication of electronic devices as a radiation/microwave absorber or high frequency equipment components. Magnetic analysis shows the large values of magnetization and coercivity for Al3+ and In3+ substituted samples, which reflect that these materials might be beneficial for the absorption of electromagnetic radiation, formation of multilayer chip inductors and recording/storage purpose.

Microwave-Assisted Magnetization Reversal in Dispersed Nanosized Barium Ferrite Particles for High-Density Magnetic Recording Tape

This paper investigates microwave (MW)-assisted magnetization reversal (MAMR) in dispersed nanosized barium ferrite (BaFe) particles. MAMR in dispersed nanosized BaFe particles was observed using vector network analyzer ferromagnetic resonance spectroscopy with coplanar waveguides, in this investigation. The average size of BaFe particles was 1750 nm3. A frequency-dependent reduction in the switching field was observed in response to an MW impulse of duration 50 ns and with a frequency of approximately 22 GHz. This result suggests that MAMR was observed in dispersed nanosized BaFe particles.

Microstructural and magnetic properties of Zn substituted nickel ferrite synthesised by facile solution combustion method

This work reports the synthesis of Ni 1-x Zn x Fe 2 O 4 ferrite (where x = 0, 0.1, 0.3, and 0.5) by a facile solution combustion method, using oxalyl-dihydrazide as a fuel. Owing to stoichiometric mixing of the starting materials and dissipation of heat during the combustion process, nano-sized spinel ferrites have been synthesised. Fourier transform infrared spectroscopy studies were carried out to confirm the presence of metal-oxide bands in spinel ferrites. X-ray powder diffraction analysis confirmed the presence of a single phase cubic nanocrystalline nature of ferrite samples. Energy dispersive X-ray spectroscopy studies showed the purity of ferrite samples. The effect of Zn substitution on the magnetic properties of these ferrites is also reported here. Magnetic studies revealed that the saturation magnetisation for these ferrite powders increases up to x = 0.3 (38.73 emu/g) and then decreases. Mossbauer measurements revealed a gradual transition from a ferrimagnetic to a superparamagnetic character with increasing concentration of Zn.

Improvement of the Superconducting Properties of GdBa2Cu3O7-δ with Nano-Sized Ferrite Addition

We have been investigating the effect of (CoFe2O4)x and (ZnFe2O4)x (x is the wt%) nano-sized ferrites on the superconducting (SC) properties of the high-Tc SC compound GdBa2Cu3O7-δ (Gd123) prepared by the conventional solid-state reaction technique. In this work, the magnetic hysteresis for pure Gd123 samples and samples added with nano-sized ferrites was measured using a superconducting quantum interference device (SQUID) magnetometer using a dc field up to 30,000 Oe. The magnetic Jc was estimated using the extended Bean model. While a clear increase in Jc values with the addition of (CoFe2O4)x nano-sized ferrites is observed, a less clear positive effect on the Jc values is observed with the addition of (ZnFe2O4)x nano-sized ferrites. These results indicate an improvement of grain connectivity, decrease of voids between the grains, and decrease of porosity in Gd123 compound resulting from CoFe2O4 addition consistent with the mechanical properties measured before. (CoFe2O4)x nano-sized ferrite addition has thus resulted in an improvement in the SC properties of Gd123 high-Tc SC compound making it more convenient for applications.

Size-dependent kinetics during non-equilibrium lithiation of nano-sized zinc ferrite

Spinel transition metal oxides (TMOs) have emerged as promising anode materials for lithium-ion batteries. It has been shown that reducing their particle size to nanoscale dimensions benefits overall electrochemical performance. Here, we use in situ transmission electron microscopy to probe the lithiation behavior of spinel ZnFe2O4 as a function of particle size. We have found that ZnFe2O4 undergoes an intercalation-to-conversion reaction sequence, with the initial intercalation process being size dependent. Larger ZnFe2O4 particles (40 nm) follow a two-phase intercalation reaction. In contrast, a solid-solution transformation dominates the early stages of discharge when the particle size is about 6–9 nm. Using a thermodynamic analysis, we find that the size-dependent kinetics originate from the interfacial energy between the two phases. Furthermore, the conversion reaction in both large and small particles favors {111} planes and follows a core-shell reaction mode. These results elucidate the intrinsic mechanism that permits fast reaction kinetics in smaller nanoparticles.

Crystallographic and Magnetic Properties of Al3+co-doped NiZnFe2O4 Nano- particles Prepared by Sol-gel Process

Al2O3 SUBSTITUTED nickel zinc nano-ferrite Alx Ni0.5-x Zn0.5 Fe2O4 (x = 0.0, 0.1, 0.2, 0.3) was prepared by the citrate sol-gel methodusing nickel, zinc, iron and aluminum nitratesand sintered at 800oC for 3 h in air. Prepared nano-sized ferrites were characterized by X-ray diffraction, High resolution transmission and scanning electron microscopy and Fourier transforms infrared spectroscopy. The estimated crystallite sizes were in the range of 24.7–32.9 nm. HR-TEM data appears that all nano-ferrite samples are composed of more or less agglomerated nanoparticles with the average particle size of nanocrystallites is ~31 nm. The impact of introducing Al ions by Ni on themagnetic properties of the prepared nano-ferrite was investigated utilizing magnetic measurements at room temperature. The changing of crystallite sizes, lattice parameter and the surface area with increasing the Al content were determined.The saturation magnetization (Ms) and coercivity (Hc) values vary from 47.894-32.314 and 70.37-60.117 G; respectively.

Gamma irradiation induced structural, electrical, magnetic and ferroelectric transformation in bismuth doped nanosized cobalt ferrite for various applications

The effects of gamma irradiation on the structural, dielectric, magnetic and ferroelectric behaviour of Bi doped cobalt ferrite, CoFe2-xBixO4 (x = 0, 0.05, 0.1, 0.5, 1.0) synthesized by glycine nitrate method before and after gamma irradiation have been investigated. A micro-strain is generated by the gamma irradiation as observed by the X-ray diffraction studies. The massive enhancement of dielectric constant in irradiated samples is attributed to the Maxwell–Wagner type of interfacial polarization. Complex impedance analysis indicates a predominant grain boundary contribution to the conduction mechanism. The frequency-dependent ac conductivity in the frequency range of 100 Hz – 1 MHz is increased on irradiation. Reduction in magnetisation was found in the irradiated samples. Remnant polarization and coercive field decreases with irradiation as obtained from P-E loop. Hence, the applications of these nanoferrites in the field of high frequency and magnetic recording devices can be favoured by tailoring the electrical and magnetic properties subjected to gamma irradiation.

Neutron Diffraction Analysis and Electromagnetic Properties of Ultrasonic Wet-Magnetic Separated NixZn1−xFe2O4 Nano-powders

Nano-sized ferrite powders less than 50 nm were prepared through combustion reaction followed by pulverizing and separating through ultrasonic-wet magnetic classification processes to study the electromagnetic properties of the nano-sized ferrites for developing an high performance electromagnetic interference filter. Neutron diffraction analysis of the ferrites prepared at 10 MPa of oxygen pressure shows that the final phase is Ni0.33Zn0.67Fe2O4 (χ2 = 1.48), which lattice parameter is 0.8412(2) nm. The residual magnetization, maximum magnetization, coercive force, susceptibility and Curie temperature of Ni0.33Zn0.67Fe2O4 particles are 0.88 Wb/m2 kg, 7.749 Wb/m2 kg, 1292 A/m, 0.068 m3/kg, and 413.93 K, respectively. Finally, the nano-sized ferrite particle less than 50 nm with more than 99% purity were obtained. The increasing frequency reduced complex permeability which real value (μr0) shows the maximum value at the less than 0.5 GHz. The dielectric constants of the powders are er′ = 5.7 and er″ = 2.5. The nano-sized Ni0.33Zn0.67Fe2O4 ferrite absorber works effectively in the range of 3–5 GHz. Typical FESEM image of Ni0.33Zn0.67Fe2O4 nano-powders.

Structural elucidation and magnetic behaviour evaluation of gallium substituted garnet ferrites

Impact of gallium (Ga) on structural, morphological and magnetic properties of yttrium iron garnet (YIG) nano-sized ferrites with nominal composition (Y3GaxFe5-xO12, where x = 0.00, 0.40, 0.80, 1.20, 1.60) has been investigated. The samples were prepared via sol-gel auto combustion route. XRD (X-ray diffraction), FESEM (field emission scanning electron microscopy) and VSM (vibrating sample magnetometer) were used to unfold the structural, morphological and magnetic properties of Ga substituted YIG ferrites. Single phase structure of all samples was confirmed through XRD. Cations distribution such as site radii, hopping bond length, shared and unshared edges of the Ga substituted YIG ferrites were also determined. Physical properties such as X-ray density (Dxrd), bulk density (Dbulk), porosity and lattice parameters were found to increase with increasing Ga concentration. FESEM images represented well crystallized and homogenous grains for YIG whereas porous structures were found for Ga substituted ferrites. The grain size of these samples was found in the nano regime (40–86 nm). Magnetic properties such as magnetic saturation, coercivity, remanence, initial permeability, Bohr magneton and anisotropy constant (K) were calculated from hysteresis loops. However, Yafet and Kittle (Y-K) angles were also calculated. Y-K angles were increased with Ga concentration in YIG nano-sized ferrites. Low coercivity and moderate magnetization suggested the use of these ferrites for electromagnetic microwave absorption and frequency agile antenna for wireless communication. Furthermore, the range of operated frequency in microwave region of these nanoferrites suggests the use of these ferrites for high frequency (S and C bands) applications.

Synthesis and Characterization of Nano-Sized Manganese Ferrites for the Adsorption of Congo red from Aqueous solution using Batch studies

A sol-gel method using citric acid has been used to fabricate nano-sized manganese ferrites (MnFe 2 O 4 ) under different calcination temperatures. The microstructure and surface morphology of manganese ferrite powders were characterized by BET, FTIR, XRD, SEM-EDX, and TEM. The nano-sized manganese ferrite was examined for adsorption of congo red (CR). As the results, the BET showed the decreasing surface area of manganese ferrites to 4.47 m 2 /g for calcination temperatures of 800 °C. The XRD pattern also indicated the alteration of amorphous phase to the crystalline structure as the calcination temperature increased. In addition, the EDX analysis of manganese ferrite at 600 °C showed the element distribution of manganese, iron, and oxygen. Beside that, the TEM images of nano-sized manganese ferrites showed a concentrated atomic mass in the exposed region in the bulk structure. Finally, the adsorption experiment showed that the adsorption of CR followed the pseudo-second order, and adsorption equilibrium was best described by the Langmuir model. Therefore, this nano-sized manganese ferrite can be a promising adsorbent for dye and textile industry. Received: 12nd April 2018; Revised: 4h July 2018; Accepted: 13rd July 2018

Microstructural evolution and performance change of a carburized nanostructured bainitic bearing steel during rolling contact fatigue process

The nanostructured bainitic (NB) bearing steel exhibits excellent rolling contact fatigue (RCF) resistance, which is critical to the service of bearing. However, the detailed microstructural evolution of the steel during the RCF process is still unclear. In this paper, a carburized NB bearing steel was studied and a detailed process investigation on microstructural evolution of the steel during the RCF progress was carried out. Results show that the nano-sized bainitic ferrite is gradually refined, and the undissolved carbides gradually flake away and some of them remain in solution during the RCF process. It is interesting to find that there are three stages for the martensitic transformation of retained austenite. During the first stage of 0–0.48 × 107 cycles, nearly all of the block-like retained austenite in the top surface transforms into martensite rapidly, and during the second stage of about 0.48–1.92 × 107 cycles, nearly no retained austenite further transforms into martensite, but when the fatigue exceeds the 1.92 × 107 cycles, the film-like retained austenite gradually transforms into martensite at a slow rate. The transformed martensite not only increases the surface hardness but further brings additional residual compressive stress in surface layer. It is analyzed from the microstructure characterization along the longitudinal section of the fatigue specimen that the fatigue crakes are initiated at subsurface of specimen, which propagate up to the surface and finally result in fatigue flake.

Structural elucidation, and morphological and magnetic behavior evaluations, of low-temperature sintered, Ce-doped, nanostructured garnet ferrites

Low-temperature sintered CexGd3.5-xFe4.5O12 (x = 0.0, 0.4, 0.8, 1.2, 1.6, 2.0 and 2.4) garnet ferrites were synthesized via a sol-gel self-combustion route. Phase, structure, morphology and magnetic investigations were done using FTIR, XRD, FESEM, and VSM, respectively. Single-phase structures of all Ce3+ substituted nano-sized garnet ferrites were confirmed through XRD. The crystallite size was decreased with Ce3+incorporation. Relevant structural parameters such as site radii, bond lengths, ionic radii, and shared edges were calculated using XRD. The vibrational spectroscopy stretching band studies were also done using FTIR. The grain size and morphology were also analyzed using FESEM. The magnetic remanance, saturation, and coercivity were found to increase systematically with an increase in Ce3+ concentration in these garnets. Switching field distribution curves were also plotted using the first derivative of the demagnetization data from MH loops. The better magnetic properties of these nanogarnets suggest their use for miniaturization of the devices in various applications.