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Series of nanosized ferrite powder Mn1-xZnxFe2O4, 0 ≤ x ≤ 0.9, were prepared through flash combustion using the metal nitrates. The nano-ferrite particles were characterized using different experimental techniques. The defects and microstructure changes of the prepared Mn-Zn ferrite samples were probed using positron annihilation spectroscopy (PAS). The single-phase structure (spinel cubic) for the ferrite samples was confirmed by the x-ray diffraction patterns and Fourier-transform infrared spectra. The cation distribution of Mn1-xZnxFe2O4 was proposed by matching the values of the experimental and theoretical lattice parameters. Also, the B-site cation distribution was modified using the three-sublattice model to adjust the values of the magnetic moments. The results of scanning and transmission electron microscopy (SEM and TEM, respectively) reflect the polycrystalline and nanosized features of the Mn-Zn ferrite nanoparticles, < 26.9 nm. The results reveal that the zinc ions enhance the grain growth from 34 nm to 60 nm. The results showed that the studied samples are soft magnetic ferrites and that their magnetic behavior changes from ferrimagnetic to paramagnetic at higher values of Zn content. The results of the Hall effect measurements revealed the presence of an inverse relationship between charge carrier concentration and zinc content. The results of the PAS measurements revealed that the positrons are trapped and annihilated in di-vacancy-type defects and/or triple junctions present in the ferrite samples. Also, the results suggested that the tetrahedral sites are preferred as the predominant positron trapping sites for high Zn content samples. The correlations between the PAS parameters and other parameters of the experimental techniques used, such as Hall effect measurements, confirmed these findings. MnZnFe2O4 nanoparticle preparation [ABSTRACT FROM AUTHOR]

Borate antimony glass doped with vanadium oxide V2O5 encoded into a [BSV glass system] was prepared with the traditional melt quenching technique. The Nickel ferrite [NiFe2O4] was prepared using Flash auto-combustion and mixed at a fixed ratio of 0.05 gm into the glass matrix to form a BSV- composite glass system [BSV / NiFe2O4], which was also prepared using the traditional melt quenching technique. The X-Ray diffraction pattern was used to characterize the glass samples and indicated their amorphous structure, with different structure phases for different levels of V2O5 content. Ranging from 200 to 1100 nm, UV–Vis spectroscopy was used to study the optical properties of the samples. The glass was found to absorb electromagnetic waves with wavelengths lower than 500 nm, while the energy gap decreased from 2.46 eV for 0.1 mol% V2O5 to 2.39 eV for 0.5 wt% V2O5. The Urbach energy also had the same behavior, and decreasing from 0.226 to 0.217 eV. On the other hand, the refractive index increased when V2O5 was added. The thermal characteristics of a [BSV / NiFe2O4] system, such as, glass transition temperature T G , onset temperature T X , crystallization temperature T C and melting temperature T m , were studied using a Differential Scanning Calorimeter. Using continuous and pulsed laser radiation, a [BSV-0.1 V2O5 / NiFe2O4] sample was exposed to laser irradiation to observe its effect on the optical features of the glass. Laser irradiation significantly changed the absorbance spectrum, while the energy gap decreased as time increased. The pulsed laser was found to have a more power-full and uniform effect compared to continuous laser. Time-dependent density function theory was used to optimize the geometrical structure of the glass and study the effect of the formation of 4- coordinate boron atoms on its properties. [ABSTRACT FROM AUTHOR]

Organic pollutants in water remain a hazard to the ecosystem, emphasizing the ongoing concern. Therefore, this study focused on the nano-sized spinel ferrite as a photocatalyst for dye degradation and probing how ferrite microstructure influences the photo-degradation efficiency. The NiFe2O4 and ZnFe2O4 nanoparticles (NPs) were synthesized using the co-precipitation and sol–gel methods, respectively. The effects of microstructure changes of pristine and annealed (450, 600, and 800 °C) ferrites were systematically examined using the positron annihilation lifetime (PAL) and Doppler broadening (DB) techniques. Rigorous analysis, featuring X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, and transmission electron microscopy (TEM), confirmed the cubic spinel nanostructure for the synthesized ferrite samples as a major phase. The optical properties of the prepared ferrite NPs were studied using the UV–Vis spectroscopy. Particle size ranged from 5.0 to 34.7 nm for NiFe2O4 and from 11.8 to 50.4 nm for ZnFe2O4. UV–Vis spectra unveiled bandgap energy ranges of 3.76–4.34 and 4.31–4.60 eV for Ni and Zn ferrites, respectively. The photo-degradation efficiency of methylene blue dye catalyzed by the prepared Ni and Zn ferrite NPs was investigated. Comparing PAL and DB parameters revealed notable differences, attributed to distinct crystallinity arising from varied synthesis methods. Remarkably, the highest photo-degradation efficiency was observed in the annealed NiFe2O4 at 800 °C and pristine ZnFe2O4 samples, surpassing others. This achievement was attributed to factors such as enhanced ordered crystallinity, increased vibrational modes, optimal particle size, fitting optical properties, and favorable defect characteristics. This study's novelty lies in highlighting the pivotal role of microstructure in governing ferrite NPs photocatalyst performance. We underscore the significance of the defect reduction, regardless of its type, size or concentration, to substantially enhance the photo-degradation efficiency. [ABSTRACT FROM AUTHOR]

This study provides a comprehensive synthesis and meticulous examination of barium hexaferrite (BHF), barium titanate (BT), and their respective nanocomposites, unveiling their potential in specific applications, including electromagnetic interference shielding. The successful formation of BHF and BT was confirmed through Fourier-transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD) analyses, revealing distinct absorption peaks indicative of the tetragonal configuration of BT and the BHF's crystal structure. Scanning electron microscopy (SEM) depicted the unique morphologies and dispersions of particles in the synthesized nanocomposites, with BHF appearing larger (~ 82 nm) than BT (~ 50 nm). Vibrating sample magnetometry (VSM) findings exhibited an increased resistance to demagnetization with the addition of BT, despite a slight decline at 75% BT concentration due to the non-magnetic nature of BT dominating. Uniquely, the study presented an in-depth analysis of the composites' conductivity, detailing their non-monotonic behavior across a frequency range. A detailed investigation into the complex permittivity and permeability revealed the composite's enhanced ability to store and dissipate both electrical and magnetic energy, a function influenced by the concentrations of BT and BHF. A pivotal highlight of this research was the significant achievement of a reflection loss (RL) value of − 45 dB at 9.3 GHz for the composite with 75% BHF, suggesting the composite's potential as an effective microwave absorber. This study represents a significant step toward designing and optimizing nanocomposites for specific applications in the realm of electromagnetic materials. [ABSTRACT FROM AUTHOR]

The purpose of this study was to evaluate the electromagnetic (EM) properties of hybrid materials made from polypyrrole (PPy) and barium hexaferrite (HF) for possible use in electromagnetic interference (EMI) shielding applications. X-ray diffraction and Fourier-transform infrared spectroscopy methods were used to confirm the presence of PPy and HF phases inside the hybrid structure. A scanning electron microscope analysis revealed that the HF particles were evenly dispersed throughout the PPy structure. The composites' dielectric and magnetic attributes were evaluated across a spectrum of frequencies, with the highest values observed in the PPy specimen. Adding HF to the PPy matrix altered the dielectric and magnetic properties of the composite, with the percentage of HF in the composite influencing its dominance over these properties. It was determined that a 25% HF content produced the most stable and efficient composite for absorbing EM waves in the X-band. This study demonstrates the potential of conductive polymer composites for EMI shielding applications, with advantages, such as improved EMI shielding, lightweight, flexibility, corrosion resistance, and tailored properties. The novelty lies in optimizing the composition of the PPy/HF composite and the characterization of its EM properties, providing insights into the design of more efficient EMI shielding materials. [ABSTRACT FROM AUTHOR]

The current work involves the use of flash auto combustion procedure to synthesize nano-ferrites Mn0.6Zn0.4LaxFe2-xO4, (x = 0.00, 0.02, 0.04, 0.06, 0.08, and 0.10) annealing at 500 °C for 4 h. X-ray Diffraction (XRD), Fourier transition infrared spectroscopy (FTIR), and high-resolution transmission electron microscopy (HRTEM) were used to characterize the structural properties of produced samples. Scanning electron microscopy (SEM) was utilized to examine the surface morphology of the samples at various Lanthanum concentrations. From XRD, the spinel cubic structure for all samples with few traces of secondary phase at high La concentrations is assured. The crystallite size is estimated to be in the nanoscale range of 13.16–18.13 nm using the Debye–Scherrer formula. The appearance of characteristic vibrational bands near 460 cm−1 and 563 cm−1, which correspond to the octahedral and tetrahedral sites, respectively, confirms the formation of the spinel structure. SEM micrographs show that the grains are nearly irregular in shape, and the accumulation of La+3 ions at the grain boundaries exerts tensile strength and pressure on the grain itself, reducing the grain size. The particle size estimated by TEM coincides well with the crystallite size determined by XRD. The thermogravimetric analysis, (TGA), was used to investigate the thermal properties of the nanoferrites from room temperature to 1000 °C. In comparison to the other samples, the sample with x = 0.04 has greater thermal stability and the TEM measurement indicates that this sample has the smallest particle size. Therefore, we can assert that the thermal stability improves as the particle size decreases. The magnetic permeability was measured in the temperature range 303–773 K at a fixed frequency of 10 kHz and at various La contents. The sample with x = 0.04 has a minimal permeability value, showing that the separation brought on by La ions has diminished the super exchange contact between magnetic ions. [ABSTRACT FROM AUTHOR]

The characterization of polymeric nanocomposite thin films of polyvinyl alcohol (PVA) doped with various concentrations of copper nanoparticles (Cu–NPs) by the aid of casting technique is synthesis and detailed. The PVA/Cu nanocomposite thin films are containing wt.% = 0%, 0.04%, 0.08%, and 0.1% of (Cu–NPs). The X-ray diffraction (XRD) exhibits the semi-crystalline behavior of all polymeric films. The Fourier transform Infrared (FTIR) results show some remarkable changes in the spectral characteristics of the thin films after adding (Cu–NPs) to (PVA) solution. Scanning electron microscopy (SEM) shows partial homogeneity between the polymeric matrix and the nano filler. The Ultraviolet–Visible (UV–Vis) spectroscopy is used to measure the optical parameters. Tauc and Urbach models are used to predict optical bandgap energy (Eg), Urbach energy (Eu), and optoelectronic properties of PVA/ Cu–NPs nanocomposites. The dielectric characteristics of the nanocomposite thin films show an improvement when the nano-filler is added to the polymeric matrix. The changes in microstructure of the PVA/Cu–NPs composite thin films are analyzed by the positron annihilation lifetime (PAL) and the Doppler broadening (DB) techniques. [ABSTRACT FROM AUTHOR]

The effects of poly (vinylidene fluoride, PVDF) on barium zirconate titanate nanoparticles has been studied. Different concentrations of (BZT-PVDF) nanocomposites using the formula [x (PVDF)/(1 − x) BZT] (where x = zero, 0.2, 0.4, 0.6, 0.8 and 1) were prepared using the hot pressing method. The BZT nanoparticle was prepared using the tartrate precursor route method. The Dc resistivity as a function of reciprocal temperature (1000/T) K−1 for the composite samples has been studied. The dielectric constant (ε) increases with the amount of BZT, which can be described as the increase of interfacial space charge polarization between (PVDF-BZT) nano-composites and the increase in the ionic mobility of the polymer. The ferroelectric hysteresis of prepared nano-composites has been investigated. The increase of BZT content raises the slope of the hysteresis loop and hence the dielectric polarization, which may be attributed to the dominance of smaller grain size and tetragonality. The increasing in dielectric properties for the prepared samples is very useful in industrial applications, such as sensors, actuators and transducers. [ABSTRACT FROM AUTHOR]

The Ni-Al ferrite nanoparticles are synthesized by the flash auto-combustion method, and PANI is synthesized by the situ-chemical oxidative polymerization method. NiAl-ferrite/PANI/ x (PANI) Nanocomposite Films (x = 0.6 and 0.8) were prepared using a solution casting process. The X-ray results of the NiAlxFe2-xO4/PANI composite manifest that the Ni-Al ferrite fully interacted with PANI molecules and the Ni-Al ferrite particles are embedded in the PANI chains from TEM and SEM images. The dielectric parameters ϵ′, ϵ″ and tan δ decreased with the increase in the frequency of the applied field. The modulus M″ spectra of the investigated samples show two relaxation peaks in two frequency regions. In Cole–Cole plot of M′ versus M″, a semicircular trend is observed, i.e. a non-Debye criterion. The presence of PANI in the NiAl0.6Fe1.4O4/PANI composite films reduces the magnetic properties of the composite samples leading to the decrease of saturation magnetization and remanence magnetization. [ABSTRACT FROM AUTHOR]

Recently glass composition with magnetic material nanoparticles has attracted a lot of interest by studying different compositions and ratios, which can be useful in controlling the composition's electrical, magnetic, and optical properties. In our study, borate oxide glasses were prepared using melt-quench technique with composition samples is (50-x) B2O3 + 50 Sb2O3 + x V2O5 encoded into [BSV glass system] where x = (0, 0.1, 0.2, 0.3, 0.4 and 0.5 wt.%). Nickel ferrite was also prepared using Flash auto-combustion and mixed with the glass matrix to form a BSV composite glass system. These glasses were investigated by X-ray diffraction, transmission electron microscopic, different dielectric properties, and Fourier transform infrared. Further results show the cubic spinel structure of Nickel ferrite in XRD, and the particle size obtained from TEM images agrees with the size calculated from XRD at 25.52 nm. TEM of BSV glass system gives that the V2O5 nanoparticle was grown inside the borate glass matrix homogenous in the form of nanorods. It shows that the relaxation peaks shift toward lower frequency, and the conductivity increase by increasing vanadium oxide content in the BSV glass system. The ratio of the V2O5 content to the ferrite content determines the impact of ferrite addition to the glass matrix on the electrical properties. By comparing the dielectric constant for the same sample with and without ferrite, the dielectric properties increase for increased V2O5 concentration. [ABSTRACT FROM AUTHOR]

The problem of the present work is to synthesize a nanomagnetic material with low TC below 45 °C and its particle size below 30 nm to be appropriate material for convert magnetic loss into heat energy. A series of Cu0.4Zn0.6+yZryFe2–2yO4 nanoparticles compositions where y = (0.05, 0.1) were synthesized via citrate sol–gel method. The prepared samples were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The grains were observed from SEM confirming the crystalline structure of the ferrite which was detected by X-ray diffraction. Magnetic hysteresis loop measurements illustrate that materials exhibit soft magnetic properties at low Zr content, while at higher Zr content all materials behave as superparamagnetically without any saturation magnetization Ms. The initial magnetic permeability ( μ i ) at frequency 10 kHz as a function of temperature was measured. A sudden change in μ i appears around Curie temperature, making our samples good candidates for magnetic temperature transducer (MTT) devices. The DC resistivity for sample at y = 0.05, 0.1 was studied. The resistivity decreases linearly with increasing temperature within the given range of temperature up to 666 K for all samples. The dielectric constant of all samples is nearly independent on temperature through the range of 450 to 600 K which is a common character of ferrites. The dielectric loss was found to increase by increasing temperature, which may be related to the increase in AC conductivity. Hyperthermia measurements show the maximum specific power loss and temperature increase were 26 w/gr and 43 °C, respectively, for sample containing Zr = 0.05, after 2 min of measurements. One of the real applications of the material is that it is used as an effective method in tumor treatment by exposing the patient to external magnetic field. [ABSTRACT FROM AUTHOR]

In this work, the dependence of magnetization temperature for α'-MnB nanoparticles has been simulated to predict magnetocaloric effect (MCE) parameters of α'-MnB nanoparticles. The results reveal that MCE of α'-MnB nanoparticles covers a large range of temperature between 300 and 550 K. We suppose that α'-MnB nanoparticles can be used as a single function magnetic material for magnetic refrigerator (MR) which can be used in the automotive, food, or aerospace industries. [ABSTRACT FROM AUTHOR]

In this investigation, it is used a phenomenological model to predict the thermomagnetic properties through making simulation of experimental isofield thermo-magnetization curve for Sc doped Th2NiC2 superconductors. Consequently, the magnetocaloric effect (MCE) of Sc doped Th2NiC2 superconductors, in the vicinity of superconducting phase transition, is simulated, calculating MCE parameters. The results show that MCE of Sc doped Th2NiC2 superconductors are inverse type in temperature range of superconducting phase transition. The behavior of MCE in Th1.9Sc0.1NiC2 and Th1.8Sc0.2NiC2 samples recommends that they can fruitfully be utilized as very low-temperature magnetic refrigerants between 7 and 11 K especially in radiation detectors for outer space research. [ABSTRACT FROM AUTHOR]

A phenomenological model (PM) is applied to simulate the magnetocaloric effect (MCE) of Ca3Co2O6 (CCO). On the basis of PM, MCE parameters of CCO are concluded as results of simulation for magnetization vs. temperature under 5 T magnetic field. The maximum value of absolute value of magnetic entropy change is 2.21 J/Kg.K. The values of full-width at half-maximum, relative cooling power and refrigerant capacity are 64 K, 141 and 101 J/Kg, respectively, finding that CCO is a prospective material in magnetic refrigeration (MR) over cryogenic temperature between 0 and 100 K. CCO sample could work as an adequate magnet in MR with limited eddy and little loss of hysteresis. Thus, magnets like CCO sample can do a significant role in the fabrication of various eco-friendly devices. It is recommended that CCO sample is a significant and promising magnet in MR for liquefying nitrogen gas. [ABSTRACT FROM AUTHOR]

Physical, structural and optical properties of thin films of PVA and PVA with different content of SrCuTi2Fe14O27 W-type hexaferrite are investigated in the present work. The hexaferrite is prepared by the ceramic method, while the thin films are prepared by the casting method. The physical and structural features are studied by using X-ray diffraction patterns (XRD) and Fourier transform infrared spectroscopy (FTIR). The XRD indicates the formation of W-type hexagonal ferrite besides the M-type and spinel ferrite. The observed FTIR spectra indicate information about the vibration modes in this studied samples. The optical analysis is done and the calculated direct optical energy band gap is increased, while the indirect optical energy band gap is decreased. The Urbach tail (Eu) energy decreases with increasing SrCuTi2Fe14O27 to PVA, respectively. The band gap from ε′′ plot (Ego) and refractive index (n) values are calculated from the optical data for all investigated samples. [ABSTRACT FROM AUTHOR]

The spinel ferrite Ni1–xMnxFe2O4 system (x = 0.0, 0.2, 0.4, 0.6, 0.8 and 1.0) have been successfully synthesized by using the flash auto-combustion method at 600 °C for 2 h. The annealed powders were characterized by X-ray diffraction (XRD), IR spectroscopy, transmission electron microscopy and scanning electron microscopy. The structural analysis confirms the formation of spinel phase with the presence of small ratio of a secondary phases. It was noticed from the XRD data that the increasing of Mn2+ content increases the lattice parameter from 8.345 to 8.421 Å and the size of crystallite decreases from 33.63 to 27.30 nm. The theoretical density ρx and the area of crystallite surface were calculated. IR study reveals the presence of tetrahedral and octahedral absorption bands ν 1 and ν 2 with two weak bands ν 1 ′ and ν 2 ′ . The morphological observations show the formation of agglomerated grains with different shapes and sizes. [ABSTRACT FROM AUTHOR]

NiAlxFe2-xO4 (where x = 0.00, 0.20, 0.40, 0.60, 0.80, and 1.00) nanoparticles (NPs) are synthesized using the flash auto combustion method where CO (NH2)2 is used as a fuel. NiAlxFe2-xO4 nanostructure is characterized by X-ray diffraction (XRD) and Rietveld refinement by using FULLPROF Suite. SEM and TEM analysis are used to study the morphology of the samples, the size and the shape of the crystallites respectively. The morphology of the samples showed the creation of uniform and spherical structural with a narrow size distribution. The XRD results and Rietveld refinement show that the lattice contains single phase spinel structure with Fd3m space group. The average crystallite size is calculated by two methods, the Debye-Scherer formula and it is found to decrease from 23.9 to 14.3 nm, while using Williamson–Hall (W–H) method, it is found to decrease from 18.89 to 10.1 nm. Magnetic properties are studied at room temperature. Theoretical and experimental magnetic moments are decreased with increasing Al content. Also, the magnetic measurements show that the samples exhibited ferrimagnetic behavior and the initial magnetic permeability, the saturation magnetization, the remnant magnetization, the coercivity, and the magnetic anisotropy constant are decreased with increasing the non-magnetic Al content. [ABSTRACT FROM AUTHOR]

Lead zirconate (PZ) nanopowders were synthesized by the treatment of precursors with high-energy ball milling for a relatively short time. The effects of ball milling time and rotational speed on the produced nanomaterial were investigated. The calcination temperature of the ball-milled powder was determined from the thermogravimetric analysis (TGA) and the differential scanning calorimetry (DSC) results. The structural properties of the calcined nanoparticles were studied by Fourier transmission infrared (FT-IR), x-ray diffraction (XRD), and transmission electron microscope (TEM). Well-crystallized PZ nanopowders were obtained after heating at 800°C for 3 h. The diffraction data were refined by the Rietveld method to accurately determine the crystallographic information. Williamson-Hall, Halder-Wagner, and size-strain plot methods were employed to investigate the average crystallite size and lattice microstrain in the prepared samples. The XRD and TEM images confirmed the formation of nanoparticles with an average size in the range of 20–43 nm. The band gap of the nanopowders varied from 3.11 eV to 3.28 eV as established by diffuse reflectance measurement. [ABSTRACT FROM AUTHOR]

NiFe2O4/PANI nano-composite with different polyaniline (PANI) content (25%, 50% and 75%) is synthesized. The NiFe2O4 (NF) is prepared by the flash auto combustion method and annealed at 400 °C for 2 h. The PANI is prepared by oxidative polymerization of aniline. The X-ray diffraction (XRD) technique confirmed that the NiFe2O4 particles are successfully dispersed in the PANI matrix with single phase structure. The characteristic absorption bands are observed from infrared (IR) spectra for the pure NF, pure PANI and their nano-composite. The dielectric constant ( ε ′ ) behavior of NF/PANI nano-composite at higher PANI content tends to be a polymer behavior. The Curie temperature decreased by increasing the PANI content and it is attributed to the basis of A-B exchange interaction due to the variation of Fe 3 + content among the octahedral and tetrahedral sites. The values of the saturation magnetization (Ms), remanence magnetization (Mr), coercivity (Hc), area and squareness (Mr/Ms) are measured by using a vibrating sample magnetometer (VSM). [ABSTRACT FROM AUTHOR]

A phenomenological model (PM) is applied to simulate magnetocaloric effect (MCE) of YbFe2As2 (YFA) sample. Based on PM, MCE parameters are deduced as the results of simulation for magnetization versus temperature under 5 T magnetic field. The maximum value of magnetic entropy change is 2.55 J/kg K. The values of full-width at half-maximum relative cooling power and refrigerant capacity are 34 K, 87 J/kg, and 62.6 J/kg, respectively. It is recommended that YFA can be used as an effective material of magnetic refrigerator over a temperature range, covering a significant range of temperature between 0 and 50 K. This indicates that YFA is considered as the MCE material functioning at a liquid helium temperature zone. [ABSTRACT FROM AUTHOR]

The magnetocaloric effect (MCE) of NaFeO2 nanoparticles has been investigated by phenomenological model (PM). The simulated temperature-dependent magnetization data are in good agreement with the experimental one. Based on PM, the MCE parameters obtained as results of simulation for temperature-dependent magnetization data. Furthermore, the simulation shows that NaFeO2 nanoparticles have a prospective importance in magnetic refrigerants over a wide temperature range, including room temperature. This gives NaFeO2 nanoparticles potentially practical for MR. [ABSTRACT FROM AUTHOR]

Nanoferrites of Ni0.1Cu0.2MgxZn(0.7−x)Fe2O4 (x = 0.0, 0.15, 0.25, 0.35, 0.45, 0.55 and 0.70 wt%) system fabricated using flash auto combustion technique. All investigated samples annealed for 2 h at 600 °C. XRD, FTIR and TEM were utilized to evaluate the structural characterization of as-prepared samples. The electrical DC resistivity of the investigated samples is evaluated as a function of frequency and temperature. The initial magnetic permeability (μi) is dependent on the temperature and was measured at constant frequency 1 kHz and 10 kHz of the sinusoidal wave. A single-phase of spinel structure was formed and with increasing Mg content the peak (311) of 100% intensity decreases, which demonstrates the presence of Mg, which slows down the growth of the crystal as X-ray result. The FTIR spectra of the prepared ferrite samples are distinguished by the presence of two strong absorption bands (ν1 = 554 cm−1) and (ν2 = 449 cm−1). The morphological observation is determined by the transmission electron microscopy (TEM) and shows that the particles size ranged between 26 and 39 nm. It can notice shifted Curie temperature (Tc) to a higher temperature by increasing Mg content. Mass attenuation coefficient (μm), mean free path (λ), half value layer (X1/2), tenth value layer (X1/10) and effective atomic numbers (Zeff) for the studied samples, have been simulated using FLUKA (2020.0beta.2), while energy change from 15 × 10–3 to 153+ keV with increasing Mg concentration, both μm and Zeff decrease. The largest value of μm and Zeff when x = 0% while sample x = 0.35% has a minimum value of λ, X1/10 and X1/2. [ABSTRACT FROM AUTHOR]

In this work, we prepared Co1–xMnxFe2O4 (CMFO) ferrites at different levels of doping x = 0.0, 0.1, 0.3, 0.5 and 0.7 using flash auto-combustion method, aiming to obtain promising results more than CoFe2O4 ferrite prepared by other methods. The results show an increase in lattice constant of CMFO with Mn content. In addition, there are many intra-granular pores and significant fusion of the small grains into larger grains. The dielectric properties of CMFO ferrites are enhanced with Mn content. Furthermore, saturation magnetization (MS) and remanent magnetization (Mr) of CMFO are improved slightly with Mn content up to x = 0.1 and then decrease with higher Mn content. The coercivity (HC) of CMFO ferrite decreases with Mn content until it reaches minimum value of 971 Oe for level of Mn substitution x = 0.5; on further Mn content (X = 0.7), it is observed that Hc increases to 1249 Oe. In comparison to previous works, HC (x = 0) and MS and Mr for our sample (x = 0.1) are significantly more than corresponding values obtained for CoFe2O4 ferrite prepared by other methods. [ABSTRACT FROM AUTHOR]

Composite samples (1 − x) Sr0.2Ba0.8TiO3 "BST" + (x) Ni0.1Cu0.2Zn0.15 Mg0.55Fe2O4 "NCZMF", where (x = 20%, 40%, 60% and 80%) are synthesized using high-energy ball milling technique. The structural characterization for synthesized samples was carried out using X-ray diffraction which confirms that both main phases BST (ferroelectric phase) which has tetragonal structure with space group p4mm and spinel NCZMF (ferrimagnetic phase) which has cubic structure with space group Fd-3m are presented as pure phases. The DC resistivity was measured as a function of temperature and it was found that the behavior of activation energy is similar to the electrical resistivity and in general the resistivity is controlled by the weight fraction of BST phase. P–E hysteresis loops for composite samples were recorded using Sawer–Tawer modified circuit. It is noticed that as the concentration of ferrite increases, the P–E hysteresis loop becomes narrow which indicates the damage of the ferroelectric phase order BST due to addition of ferrite content. [ABSTRACT FROM AUTHOR]

The effect of Co content on magnetocaloric effect (MCE) in CoxZn1−xFe2O4 (CZF) with x = 0, 0.1, 0.2, 0.3, and 0.4, prepared by auto-combustion technique, has been investigated by phenomenological model. The results show that MCE for CZF nanoparticles is enhanced strongly with Co content especially for high Co content samples. In addition, MCE in CZF nanoparticles is tunable with Co content over a large operating temperature range. MCE of CZF nanoparticles are significantly better than MCE of Ni58Fe26Ga28, MnAs films, and Ge0.95Mn0.05. It is recommended that that MCE in CZF nanoparticles is favorable for magnetic refrigeration in a wide temperature range, including room temperature. [ABSTRACT FROM AUTHOR]

The magnetocaloric (MC) properties of Ni0.5Cu0.25Zn0.25Fe2O4 (NCZFO) nanoferrite samples prepared under different annealing temperatures were simulated by phenomenological model. The results indicate that MC properties of NCZFO nanoferrites change none monotonically with annealing temperature. Furthermore, the range of temperatures between 407 and 515 K are suitable for NCZFO nanoferrites to be used as an effective material in magnetic refrigeration (MR). It is concluded that NCZFO nanoferrites are very practical MC materials in MR for high temperature applications like automotive, aerospace, and food industries. [ABSTRACT FROM AUTHOR]

Nanocrystalline lead zirconate titanate (PZT) powders were synthesized via a modified Pechini method. The effect of heat treatment temperature on the microstructural properties was studied using X-ray powder diffraction. The explored temperatures were identified from the TGA/DSC measurement and it is found that the crystallization starts from 550 °C. Rietveld refinement was applied to study structural changes and to quantitatively assess the fractional content of lead monoxide, identified in nano-PZT powders. Lebail method was carried out to the XRD pattern to accurately determine the peak broadening and position. Size-Strain Plot and various Williamson-Hall methods were used to calculate the lattice microstrain and crystallite size. The minimum strain was noticed in the pure tetragonal-PZT sample. TEM technique was also employed to study nanopowders and to confirm the formation of small-sized particles. The energy band gap was determined by diffused reflectance measurements and found to range from 3.17 to 3.29 eV. [ABSTRACT FROM AUTHOR]

The effect of trivalent ions (Al3+, Bi3+, and Mn3+) substitutions on magnetocaloric effect (MCE) of M-type ferrite BaFe12O19 (BaM) has been investigated by a phenomenological model. It is shown that the presence of Al3+, Bi3+, and Mn3+ ions in BaM makes remarkable variations for MCE. It is concluded that MnBaFe11O19 is more practical than BaM, BiBaFe11O19, and AlBaFe11O19 due to a larger MCE, and its Curie temperature is closer to room temperature. MCE of BaM can be tuning with remarkable values by doping suitable ions. [ABSTRACT FROM AUTHOR]

In this work, polymeric composites based on room-temperature vulcanized (RTV) silicon rubber incorporated with different NiCr0.2Fe1.8O4 (NCF) content are prepared. The results indicate the well dispersion of various micron-sized particles of NCF with low agglomerations. The decrease in the density is the most advantage property that allows us to obtain the light magnetic material for industrial applications. It is shown that the rubber occupies the porous and defects between NCF particles. It is found that dielectric constant is enhanced with RTV content and decreases with increasing selected frequency for all samples. The electrical conductivity of composite is enhanced with both RTV content and the heat treatment temperature of composites. The saturation magnetization is strongly dependent on NCF content in RTV matrix. [ABSTRACT FROM AUTHOR]

The samples of nano-crystalline CoLaxFe2−xO4 were prepared by ceramic method. The results show the formation of cubic inverse spinel phase for all CoLaxFe2−xO4 samples in addition to impurity phase formation of LaFeO3 for high La content samples. The crystallite sizes for all samples are almost 30 nm. The dielectric measurements show that the presence of La enhances the values of dielectric constant at high temperature, demonstrating Debye relaxation. The DC electric resistivity decreases with La content, suggesting that the conduction phenomenon in these samples is due to hopping of charge carriers. The positron annihilation spectroscopy shows that the large size defects decrease with La for low content samples. However, at higher La content (x = 0.25), the agglomeration of the defects is the dominant process. The CoLa0.25Fe1.75O4 sample shows a different type of defect from other samples. The high electrical resistivity and low tan δ recommend that these samples can be used in power applications that require negligible eddy currents. [ABSTRACT FROM AUTHOR]

Strontium barium titanate, Sr1−xBaxTiO3 (BST) was prepared using tartrate precursor method. The X-ray diffraction patterns were used for analyzing the phase compositions. Lattice parameter, crystallite size, X-ray density, bulk density and porosity were calculated. The IR spectra confirm the results of X-ray for the formation of the perovskite structure. The surface morphology of BST at different barium content (x) was studied by scanning electron microscopy (SEM). The DC resistivity was studied as a function of temperature and the mechanism of conduction at different Ba content was established. [ABSTRACT FROM AUTHOR]

The effects of Zr+ 4 and Zn+ 2 substitution on the electrical, dielectric and spectral properties of non-stoichiometric Cu1−xZnxZryFe2−yO4 + δ and stoichiometric Cu1−xZnx + yZryFe2 − 2yO4 ferrites prepared by double sintering ceramic technique have been investigated. IR absorption spectra confirm the formation of spinel structure. On the other hand, IR spectra can give an idea about the change of molecular structure of ferrites system due to the perturbation that occurred in Fe3+-O2− bond by introducing Zn and Zr elements. The phase identification of nonstoichiometric (ns) and stoichiometric (s) samples was confirmed by the presence of endothermic peak from DTA curves at around 936 ∘C in agreement with X-ray diffraction and IR results. The calculated low values of activation energies for conduction are in the range that suggests the conduction is due to thermally activated mobility and the presence of hopping conduction mechanism. Thermoelectric power exhibits positive sign for most s and ns samples. The concentration of charge carrier is constant in the ferromagnetic region. It is also noted that the dielectric constant decreases with increasing Zn and Zr contents. From the above discussion the samples containing Zn and Zr elements have lower ΔBpp values with low energy loss. From the ESR analysis it can be confirmed that the addition of Zn and Zr generally decrease the power loss which is very important in the application for the manufacturing of a material which is used as a core of transformer at the microwave frequencies. [ABSTRACT FROM AUTHOR]

In this research, we detected superior values of the initial magnetic permeability for electrodeposited Ni–Co–P-M-type BaFe12O19(BaM) composite films as magnetic soft–hard composites with a large amount of entrapped BaM particles. Furthermore, the initial magnetic permeability of Ni–Co–P-BaM composite films is significantly large and is comparable with corresponding values of the excellent corresponding values for permalloys, Sendust, Co-based amorphous alloys, nanocrystalline (Fe-based) and commercially sintered MnZn ferrite cores. Therefore, Ni–Co–P-BaM composite films are very attractive for magnetic devices, such as magnetic inductors, transformers, and magnetic recording heads. [ABSTRACT FROM AUTHOR]

We demonstrate that the promising effect of inclusion of single magnetic-domain type-M hexaferrite of barium (BaM) particles in polystyrene (PS) polymer (BaM/PS weight ratio = 2/1). The results show that the coercivity of BaM particles remarkably increases from 714 to 3772 Oe and remanence increases from 2.07 to 5.41 emu.g-1 when they embedded into PS. Moreover, magnetic coercivity and squareness of the BaM-PS are significantly larger, and is comparable with corresponding values of other BaM-polymer composites. Therefore, BaM-PS composite enforce itself as the modern potential materials with tendency of replacing existing composite materials in several applications. [ABSTRACT FROM AUTHOR]

A sery of ferrite samples, Ni0.1Cu0.2MgxZn0.7-xFe2O4, (x = 0.00, 0.15, 0.25, 0.35, 0.45, 0.55 and 0.70) have been prepared by the standard ceramic techniques, sintered at 1200°C for 2 h, and their crystalline structures were investigated by using X-ray diffraction, which confirmed the formation of Ni0.1Cu0.2MgxZn0.7-xFe2O4 phase. The presence of Mg content increases the crystallinity of the given ferrite which is considered as catalyst for the accomplishment of the solid state reaction. The lattice parameter and crystallite size were calculated from XRD. The cationic distribution was estimated from the theoretical values of lattice parameters. The IR spectra analysis has been studied.The dielectric constant for the ferrite system Ni–Cu–Zn gradually increases with temperature up to nearly Curie temperature and then increase sharply beyond the Tc. The Curie temperature obtained from the versus έ T is in agreement with the Curie temperature obtained from other measurements. Dielectric loss tangent (tan δ) has the same behavior as dielectric constant . (έ) A minimum value of dielectric loss tangent (tan δ) for the system "Ni–Cu–Zn" was observed at x = 0.45. Magnetic permeability has been studied. The dependence of initial permeability on temperature exhibit a peak which is called Hopkinson peak (HP) in the vicinity of Curie temperature and confirmed the phase purity of ferrite sample. The increasing of porosity and decreasing of grain size play an important role in decreasing μi. It is clear that the value of Tc is found to increase by increasing the concentration of diamagnetic substitution Mg for "Ni–Cu–Zn" system. [ABSTRACT FROM AUTHOR]

Mössbauer and x-ray diffraction spectroscopic analyses were carried out on ZnFe2O4 nanoferrite of average size 17 nm after γ-irradiation with three absorbed doses of 291 kGy, 582 kGy and 873 kGy using 60Co source. The obtained Mössbauer analysis data were unchanged before and after irradiation for the investigated sample. A broad paramagnetic doublet spectrum was observed which is refereeing to octahedral high spin Fe3+ in the B-site of the ZnFe2O4 structure. The x-ray powder diffraction analysis has revealed that there is slight shift in some of the diffracted lines of the characteristic XRD pattern due to irradiation which is attributed to change in the lattice parameter. The estimated net magnetic moment was decrease after irradiation due to redistribution of the cations occupying the tetrahedral and octahedral sites. These results are discussed in the light of γ-rays interaction with ferrite lattice. [ABSTRACT FROM AUTHOR]

The systems MgCuZnFe2O4 doped (0-0.6 wt% Ta) are prepared by the general ceramic method using the sintering temperature at 1200°C. The variations of the sintered density, lattice parameter, jump length of electrons, and initial permeability were studied. A maximum density was obtained at 1200°C during the preparation process. The electrical resistivity decreases with increasing tantalum (Ta) content upto 0.1 wt% and then increases for higher concentrations. The initial permeability and the change carries mobility increase upto 0.1 Ta and then decreases. The jump length decreases with enhancing Ta ions because the substitution of Ta ion with small size instead of Fe3+ at the A sites increase the concentration of iron ions at the B sites. The increase of the iron content causes the decrease of the jump length of electrons between Fe3+ and Fe2+. These improvements of the magnetic properties give some light about the importance of these compositions to be used in technology. [ABSTRACT FROM AUTHOR]

Abstract A series of Co-Zn ferrite samples substituted by Mn were prepared by the usual double sintering ceramic technique. The x-ray diffraction patterns of the samples confirmed the formation of single-phase spinel structure, and x-ray analysis supply data that suggests the cation distribution of the material. The tetrahedral and octahedral radius permits one to calculate the theoretical lattice parameter and the bond lengths Fe-O at A and B sites. The particle size of the given samples was measured from the Scherer equation and a correlation was found between particle size, and structural and magnetic properties. The XRF confirmed the presence of stoichiometric solid-state reaction in the material. The saturation magnetization Ms decreases continuously with increase of Mn content. For Co0.6 Zn0.4 Mnx Fe2-x O4, the Neel model for the two sub-lattice can be used up to x = 0.8 to explain the compositional variation of magnetic moment due to the reduction of the A - B interaction. Above x = 0.8, the reduction of the B-B interaction is responsible for an increase in the magnetic moment due to the canting effect. [ABSTRACT FROM AUTHOR]

A series of Li0.5FexGa2.5-x O4 systems were prepared for x = 0, 0.25, 0.5, 0.75 and 1 by the general ceramic method. X-ray diffraction showed that all compositions have single phase Spinel cubic structure. The lattice parameter increased with enhancing iron concentration. The thermoelectric coecient decreased with increasing x, and the majority carriers are holes. The increase of the jump length of hole increased the electrical conductivity. Jump-length increased with iron concentration and the rate of jumping gave rise to the electrical conductivity. The concentration of Fe 3+ ions in Lithium gallate is important, for such structures may have application in communication technology. [ABSTRACT FROM AUTHOR]

Nano-crystalline NiCrxFe2-xO4 (where x = 0.0, 0.2, 0.4, 0.6, 0.8 and 1.0) system have been synthesized by the flash auto-combustion method annealed at 400°C for 2h. The X-ray diffraction (XRD) technique was employed to confirm the single phase formation of nickel ferrite. The transmission electron microscopy (TEM) was used to characterize the nanostructure of ferrite. All samples were crystallized in a spinel cubic structure. The (IR) spectra was recorded in the range from 200-4000cm^-1. The absorption bands at 601cm^-1 (ν1 and 410 cm-1 (ν2) were assigned to tetrahedral (A site) and octahedral (B site) groups complex. The morphological observation which was determined by scanning electron microscopy (SEM) shows agglomerated grains with different shapes and sizes. The values of lattice constant, X-ray density, bulk density, and porosity were calculated. The decrease in the lattice constant was endorsed to the difference in ionic radius of both Fe3+ (0.67 Å) and Cr3+ (0.64 Å). The particle size was found in the range of 18-25nm by X-ray and TEM analysis. The porosity has an inverse character with the bulk density. [ABSTRACT FROM AUTHOR]

The electrical measurements and positron annihilation lifetime spectroscopy (PALS) of LaxCoFe2−xO4 (x = 0.05, 0.1, 0.15, 0.2, 0.25, and 0.3) synthesized by two different techniques (citrate-gel autocombustion and autocombustion flash techniques) were carried out. The dielectric constant (εʹ) and dielectric loss (tan δ) were reduced with La concentration at low La value samples. On contrary, La enhanced the values of εʹ and tan δ at high La content samples. AC-resistance measurement recommended that hopping conduction prevails in the studied samples. PALS indicated that defects present at grains’ boundaries and vacancy-type defects in the structure are not changed with different La3+ contents. PALS also indicated the presence of large free volume regions between grains. Finally, it is recommended that these prepared samples are preferable for use in applications like microwave devices, actuators, isolators, and phase shifters. [ABSTRACT FROM AUTHOR]