Sharif Digital Repository

The influence of indium on the properties of Cu0.5Zn0.5Fe2O4 nano ferrites synthesized by sol–gel auto-combustion technique was studied. X-ray diffraction (XRD) analysis demonstrated that pure and substituted ferrites possessed cubic spinel structure. The lattice parameter increases with the inclusion of In3+ for x ≤ 0.16 and decreases subsequently. A linear decrease in crystallite size was found as concentration of indium increased. X-ray density, strain, and dislocation density were increased as indium content increases. Hopping lengths as well as radii of A and B sites revealed increasing behavior up to x = 0.16 and decreased thereafter. The spectral bands indicated the formation of... 

This article presents a model to simulate the behavior of a magnetic shape memory alloy while harvesting vibratory energy. In this type of energy harvester, magnetic shape memory alloy element is placed in the air gap of a ferromagnetic core which conducts the magnetic flux. Two apparent coils are wound around a ferromagnetic core: one to produce bias magnetic field by passing a rectified electric current and the other to serve as an energy pickup coil. Applying compressive time-variant strain field to magnetic shape memory alloy element changes its dimensions and magnetic properties as well. Presence of the bias magnetic field returns magnetic shape memory alloy element to its initial state... 

An investigation into the addition of different weight percentages of Fe3O4 nanoparticles to find the optimum wt.% and its effect on the microstructure, thermal, magnetic, and electrical properties of aluminum matrix composite was conducted using the powder metallurgy method. The purpose of this research was to develop magnetic properties in aluminum. Based on the obtained results, the value of density, hardness, and saturation magnetization (Ms) from 2.33 g/cm3, 43 HV and 2.49 emu/g for Al-10 Fe3O4 reached a maximum value of 3.29 g/cm3, 47 HV and 13.06 emu/g for the Al-35 Fe3O4 which showed an improvement of 41.2%, 9.3%, and 424.5%, respectively. The maximum and minimum coercivity (Hc) was... 

In this study Fe3O4/CMC magnetic nanoparticles were synthesized through co-precipitation method. Afterward, laccase from Trametes hirsuta was immobilized onto Carboxymethyl cellulose (CMC)-coated magnetic Fe3O4 nanoparticles by covalent bonding between carboxyl groups of carboxymethyl cellulose and amine group of laccases. Also, the resulted magnetic nanoparticles and immobilized laccase were characterized by Fourier-transform infrared spectroscopy (FTIR), scanning electron microscope (SEM) and dynamic light scattering (DLS) analysis. Moreover, the vital factors in enzyme immobilization, such as contact time, amount of N-hydroxysuccinimide (NHS), and the amount of nanoparticles were... 

In this work, central composite design (CCD) as a statistical experimental design method is performed to prepare nickel nano-particle of different magnetic domain regimes by the modified polyol process. It is shown that not only the concentration of the different chemicals but also the injection rate is determining for the morphology and magnetic properties. The average diameter of the synthesized nickel NPs is smaller than the critical single domain size and thus the single domain or pseudo-single domain nickel nano-particles can be prepared based on Day's plot  

Magnetic polyvinyl alcohol (M-PVA) films were prepared via solution casting filled with surface modified superparamagnetic nanoparticles (M-NPs). The M-NPs were coated with citric acid during synthesis. The chemical interaction between the citric acid and M-NPs was confirmed by Fourier transform infrared spectroscopy (FTIR). The average hydrodynamic diameter of M-NPs was 19.7 nm measured by dynamic light scattering DLS and appeared almost spherical in scanning electron microscopy (SEM). The M-NPs were uniformly dispersed in polyvinyl alcohol (PVA) matrix and showed high optical transparency with good mechanical properties. M-PVA hydrogels were synthesized using gamma irradiation. The... 

The synergistic effect of plasmonic Au-Ag nanoparticles (NPs) on the increase of absorption band of nano-sized TiO2 and magnetic property of Fe3O4 NPs on the separation-ability of this semiconductor was applied for preparation of eight magneto-plasmonic photocatalysts for degradation of rhodamine-6G (Rh6G) in textile wastewater. The size, structure, morphology, crystallinity and optical and magnetic properties of prepared photocatalysts have been evaluated by various characterization techniques. Their photocatalytic activities were assessed under irradiation of an intense linear 405-nm laser and a continuous solar-simulated xenon lamp. The results were demonstrated that in comparison to the... 

Indium substituted Cu[sbnd]Ni nanoferrites with nominal compositions Cu 0.5 Ni 0.5 In x Fe 2-x O 4 (x = 0.00–0.32)were successfully synthesized by sol-gel auto ignition method. X-ray diffraction patterns illustrated the single phase spinel structure for x ≤ 0.24. The lattice parameter ‘a’ increased from 8.3349 to 8.3723 Å and then it decreased for x = 0.32. X-ray density increased from 5.43 to 5.79 g/cm 3 . The average crystallite sizes lie in the range 33.21–17.78 nm. The cell volume was increased from 579.03 to 586.86 Å 3 with the substitution of indium ions into the spinel lattice of copper nickel ferrites. The compositional dependence of tetrahedral and octahedral radii was explained on... 

Recently, graphene oxide and its unconventional magnetism have attracted much interest due to their novel applications in spintronics, memory chips and theranostics. Owing to the excellent biocompatibility, cellular uptake, bio-conjugation possibilities, flexible chemical modification and characteristic broad-wavelength absorbance, graphene oxide and its derivatives have been utilized as contrast agents for various imaging modalities such as photoluminescence, photoacoustic or ultrasound. Despite their suitable applications in bioimaging and due to lack of magnetic moment, graphene oxide cannot confer magnetic resonance imaging contrast without incorporating the magnetic component. Such... 

Ceramic-magnetic nanoparticles (CMNPs) are attracting attention due to their various applications, especially in biomedical industries. Among them, spinel ferrite CMNPs have received considerable deliberations among different spinel metal oxides due to their fascinating characteristics. Spinel ferrite CMNPs are used for enhancement of the applicability of CMNPs without affecting the intrinsic advantages of iron oxide CMNPs. Spinel ferrites with doping agents have useful electrical and magnetic properties in various fields. Moreover, the replacement of metallic atoms in ferrites is promising to manipulate physical characteristics and improve their performance. Among different spinel ferrites,... 

Triboelectric nanogenerators (TENG) have been reported with attractive benefits such as adaptability, lightweight, and simple integration, are interesting for self-powered sensor design. Herein, an innovative magnetically circular layers TENG (MCL-TENG) are reported for velocity sensing and damage detection. The key role of this structure is the magnets fixed on the device, providing attractive force to move. The electrical performance of MCL-TENG under loading condition is investigated experimentally. According to the structure of the magnetic system, the MCL-TENG can effectively react to a frail striking and can be utilized to consider the speed parameters and detecting crack without the... 

The controlled and stable crystal structure, reduction in Curie temperature and semiconducting nature of oxide materials are the key factors for magnetoelectrical applications. Therefore, Co0.6Mn0.4GdxFe2-xO4 where x = 0, 0.033, 0.066 and 0.10 were synthesized to analyse the structural, morphological, magnetic, and electrical properties using a sol-gel autocombustion approach. The X-ray diffraction pattern reveals that the cubic crystallite size decreases with increasing smaller content of Gd3+ oxides without any secondary phase. Field emission scanning electron microscopy (FE-SEM) and high-resolution transmission electron microscopy (HR-TEM) study explain the complete morphology,... 

Iron-borosilicate soft magnetic composites are suitable magnetic materials for high temperature and high frequency applications. In this research two different techniques have been applied to fabricate these composites: uniaxial pressing following by sintering and spark plasma sintering. Different processing parameters including the content of borosilicate, the amount of compaction pressure and the size of iron particles have been evaluated through the study of microstructure and magnetic properties. The microstructural observations showed that the borosilicate is distributed on the iron grain boundaries enhancing the resistivity and causing the loss of eddy currents. Increasing the... 

Graphene oxide (GO) has never been considered as a Magnetic Resonance Imaging (MRI) contrast agent since it was conceived as a diamagnetic material. There is a possibility that introduction of structural defects or manipulation of oxygen functionalities in GO change its magnetic response and provided a chance for GO to be a contrast agent for MRI. For this purpose, reduced graphene oxide (RGO) was treated by irradiation and annealing procedures. The study on the magnetic properties of the samples confirmed that the competition between the structural defects and oxygen functionalities to magnetic moments determines the magnetism in RGO. © 2018  

Copper (Cu) substituted Co–]Ce nanoferrites with nominal composition of Co 1-x Cu x Ce 0.05 Fe 1.95 O 4 (x = 0.00, 0.25, 0.50, 0.75, 1.00) were prepared by sol-gel route. The sintering of the Cu doped Co–]Ce nanoferrites was done at 700 °C to investigate the desired properties of the Cu doped Co–]Ce nanoferrites. The combination of transition metal (Cu) and rare earth (Ce) were employed to tailor the characteristics of the spinel ferrites. The constant ratio of rare earth and systematic doping of Cu in Co ferrite was incorporated to see the effects of these ions in spinel ferrite. FTIR, FESEM, XRD and VSM were used to study the vibrational bands, phase, morphology, structure and magnetic... 

In this research, polyaniline@Ba0.5Sr0.5Fe12O19@MWCNTs nanocomposite was prepared via co-precipitation and in-situ polymerization methods, respectively. Microstructural, magnetic and electromagnetic wave absorption analysis of the prepared nanocomposite were studied via XRD, FESEM, VSM and VNA. Compared with Ba0.5Sr0.5Fe12O19@MWCNTs, the microwave absorption bandwidth of the coated nanocompoite with polyaniline was significantly enhanced, which increased to approxiamately 4 GHz from 3 GHz. The effective microwave absorption performance of the Ba0.5Sr0.5Fe12O19@MWCNTs nanocomposite was attributed to increase in the interfacial polarization, improvement in impedance matching as well as porous... 

NMZ ferrites doped with rare earth having spinel composition Ni0.5Mn0.3Zn0.2X0.02Fe1.98O4, whereas X = Y, Pr and Gd were synthesized by sol gel auto-ignition method. XRD, FESEM, VSM and VNA were used to determine the phase, microstructural, magnetic and electromagnetic properties of rare earths doped NMZ ferrite. XRD analysis confirms the single phase of the rare earths doped NMZ ferrite. FESEM images shows Pr doped NMZ ferrite has less agglomerations and more porous structure as compared to NMZ and other rare earths doped NMZ ferrites. Magnetic analysis shows the enhancement in saturation magnetization and remanence with the doping of Y, Pr and Gd in NMZ ferrite. Dielectric properties were... 

NMZ ferrites doped with rare earth having spinel composition Ni0.5Mn0.3Zn0.2X0.02Fe1.98O4, whereas X = Y, Pr and Gd were synthesized by sol gel auto-ignition method. XRD, FESEM, VSM and VNA were used to determine the phase, microstructural, magnetic and electromagnetic properties of rare earths doped NMZ ferrite. XRD analysis confirms the single phase of the rare earths doped NMZ ferrite. FESEM images shows Pr doped NMZ ferrite has less agglomerations and more porous structure as compared to NMZ and other rare earths doped NMZ ferrites. Magnetic analysis shows the enhancement in saturation magnetization and remanence with the doping of Y, Pr and Gd in NMZ ferrite. Dielectric properties were... 

The influence of annealing treatment on macro- and micro-texture of cold-rolled FeCo-7.15V ferro-magnetic ultra-thin foils were studied. The microstructural studies performed by field emission scanning electron microscope (FE-SEM) showed the formation of paramagnetic precipitations ((Fe, Co)3V) during annealing. During cold rolling of the FeCo-7.15V magnet, the texture components of type (113)[110], (001)[110], (111)[110], and (111)[121], all related to α and γ-fibers were formed. X-ray diffraction (XRD) and local texture measurements performed by electron backscatter diffraction (EBSD) were made on the annealed samples. Both methods revealed that the recrystallized samples have texture... 

The effect of milling time on the magnetic properties of FINEMET amorphous ribbons has been investigated using X-ray diffraction, Mössbauer spectroscopy, thermo-magnetic measurements, transmission electron microscopy and SQUID magnetometery. Ribbons were melt-spun at a wheel speed of 38 ms-1 and then mechanically milled for different periods up to 45 min. The results showed that the partially crystallization of the amorphous powder occurs during milling. TEM observations confirmed the formation of small volume fraction of the crystalline phase with ∼9 nm crystallite size in the amorphous matrix for the ribbon milled for 45 min. Thermo-magnetic measurements indicated the enhancement of the...