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Polycrystalline Mn-Co-Ni ferrite was synthesized by solid state reaction method at 950 °C. X-ray diffraction pattern indicates that specimen has a cubic spinel type structure with lattice constant varies from 8.321 Å to 8.329 Å, X-ray density was calculated 5.39 g/cm³ to 5.36 g/cm³ and approximate particle size was found 36 nm. Magnetic measurements was carried out using VSM at room temperature (RT) where saturation magnetization (Ms) was found 55 emu/g to 42.19 emu/g, coercive field (Hc) was found 165 Oe to 88 Oe and magnetic moment (μB) was found from 2.30 μB to 1.75 μB. UV-visible measurement was recorded the maximum absorption was found at wavelength 213 nm to 222 nm and direct optical band gap found 3.32 eV to 3.96 eV. [ABSTRACT FROM AUTHOR]

Researchers are taking great interest in the synthesis and characterization of MnZn ferrites due to their wide range of applications in many areas. MnZn ferrites are a class of soft magnetic materials that have very good electrical, magnetic and optical properties. The properties of MnZn ferrites include high value of resistivity, permeability, permittivity, saturation magnetization, low power losses and coercivity. The above mentioned advantageous features of MnZn ferrites make them suitable for the use in various applications. In biomedical field these ferrites are used for cancer treatment and MRI. MnZn ferrites are also used in electronic applications for making transformers, transducers and inductors. These ferrites are also used in magnetic fluids, sensors and biosensors. MnZn ferrite is highly useful material for several electrical and electronic applications. It finds applications in almost every household appliances like mobile charger, LED bulb, TV, refrigerator, juicer mixer, washing machine, iron, microwave oven, mobile, laptop, desktop, printer and so on. Therefore, the present review focuses on different techniques for synthesis of MnZn ferrites in literature, their characterization tools, effect of doping on the properties of MnZn ferrite and finally we will discuss about their applications. [ABSTRACT FROM AUTHOR]

Bismuth ferrite (BiFeO3 or BFO in short), one of the very promising multi-ferroic materials possessing a rhombohedrally distorted perovskite structure, has been synthesized using conventional solid-state reaction method. Eight sets of samples were prepared by varying initial synthesis parameters. Effects of precursors' grinding time, heating rate, quenching rate and sintering temperature on the phase, structural and spectral properties of obtained materials were systematically studied using XRD, FTIR and Rietveld methods. The results revealed that the optimal condition to obtain pure-phase BiFeO3 is using preheated furnace with sintering at 1073 K and then quenching in air for rapid cooling with intermediate grinding time of 3 h. Rietveld analysis applied on the X-ray diffraction data via Fullprof software indicated around 97% purity of the sample with the above-mentioned conditions. Deviation from the above temperature or grinding time or quenching rate leads to an increase in the phase fractions of Bi2Fe4O9 and Bi25FeO40 which are the major secondary phases formed during the synthesis of bismuth ferrite. [ABSTRACT FROM AUTHOR]

In the present work, the structural and magnetic properties of lithium-zinc ferrite ceramics of Li 0.4 Fe 2.4 Zn 0.2 O 4 composition, obtained using a complex high-energy impact including the mechanical activation of Fe 2 O 3 -Li 2 CO 3 -ZnO reagent mixture in planetary mill and radiation-thermal (RT) heating by continuous electron beam, were studied. The samples were divided into two batches: 1) with preliminary thermal synthesis; 2) without preliminary synthesis. All samples were studied by X-ray diffraction (XRD), electron microscopy (SEM) and thermal analysis (TG/DTG) techniques. It was established that the high density and low porosity of lithium-zinc ferrite ceramics can be received by using radiation-thermal heating. The samples are characterized by high values of specific magnetization and Curie temperature. Preliminary mechanical activation of the initial reagent mixture allows not only to accelerate the synthesis of ferrite materials, but also to combine the technological stages of synthesis and sintering in single stage of radiation-thermal processing. [ABSTRACT FROM AUTHOR]

The paper considers kinetic laws of lithium ferrite synthesis under heating of mixtures of the initial Fe 2 O 3 –Li 2 CO 3 reagents of different prehistory (powder, compact, mechanically activated mixture) with a high-energy electron beam. The synthesis temperature range was (600–750) °C, and the holding time was up to 120 min. The study employed an ILU-6 pulsed accelerator with electron energy of 2.4 MeV. Formation of ferrite in conventional thermal annealing at similar temperature and time conditions was studied for comparison. XRD analysis was the main method to study the synthesized samples. It is found that the rate of ferrite formation depends on both the heating method and the density and activity of the initial mixture. It is shown that high-energy electron beam heating of the mechanically activated mixture significantly accelerates ferrite production, which is indicated by decreased kinetic parameters of ferrite synthesis. [ABSTRACT FROM AUTHOR]

Mn–Zn ferrite magnetic nanoparticles (MNPs) were deposited by silica shell for magnetic separation purpose. Following the formation of MZF(core)@SiO 2 (shell), MZF@SiO 2 /BiOBr 0.5 Cl 0.5 nanocomposites were synthesized by a solvothermal route. X-ray powder diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy were used to characterize different phases, crystallinity, morphology and vibrational mode. Magnetic properties were investigated by a vibrating sample magnetometer (VSM). Chemical composition and valence state of the nanocomposites were analyzed by X-ray photoelectron spectroscopy (XPS), including energy band gap was determined by diffuse reflectance UV–visible spectroscopy. The MZF@SiO 2 /BiOBr 0.5 Cl 0.5 nanocatalyst has strong adsorption in the dark and high photocatalytic performance in degrading of rhodamine B (RhB) dye under visible light irradiation. At the end of the fourth re-cycle, removal of 30 μM RhB solution was ~80% and the recycled photocatalyst separated by external magnetic field was 90 wt% of the original. In this research, calculated valence and conduction band edges were used to explain photodegradation mechanism of the MZF@SiO 2 /BiOBr 0.5 Cl 0.5 nanocomposites. [ABSTRACT FROM AUTHOR]

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In this work, the synthesis and characterization of cobalt ferrite nanoparticles (CoFe2O4 NPs) were carried out. The characterization studies confirmed that the synthesized particles were determined to be magnetic CoFe2O4 NPs in nanoscale and cubic spinel structure. The Brunauer-Emmett-Teller specific surface area of mesoporous CoFe2O4 NPs was determined to be 145.03 m2/g. The photo Fenton-like degradation ability of CoFe2O4 NPs was also evaluated and the results demonstrated that the synergistic effect of combining of Co and Fe2O4 enabled CoFe2O4 NPs to become the promising photo Fenton-like catalyst for degradation of methylene blue (MB) from aqueous solutions. At the optimum experimental conditions (3.0 of initial pH, 25 mM of H2O2 concentration, 50 mg/L of initial dye concentration, and 0.25 g/L of catalyst concentration), 18.29% chemical oxygen demand removal and 99.75% color removal were achieved after the photo Fenton-like degradation of MB in the presence of CoFe2O4 NPs heterogeneous catalyst with near-UV radiation. [ABSTRACT FROM AUTHOR]

A series of morphology-selected copper ferrite (CuFe 2 O 4) anode materials for sodium ion batteries were firstly prepared via a highly efficient spray drying method using glycine as the complex and accelerator. It was found that the glycine/nitrate (G/N) molar ratio has an important influence on the crystallinity, morphology and electrochemical properties of sodium storage. Compared with the other prepared materials, the G/N-0.3 (glycine-nitrate molar ratio of 0.3) exhibits the most excellent electrochemical performance. The excellent electrochemical properties can be attributed to the optimized molar ratio of glycine-nitrate, which induce a good crystallinity with a proper porous structure, thereby improving the cycle life of the battery. [ABSTRACT FROM AUTHOR]

This study presents a fabrication and electrochemical properties of nickel ferrite/graphene nanocomposite as electrodes material for supercapacitor application. The as‐prepared electrode was characterized using X‐ray diffraction, scanning electron microscopy, transmission electron microscopy and X‐ray photoelectron spectroscopy. The electrochemical properties were measured using cyclic voltammetry, galvanostatic charging/discharging methods and electrochemical impedance spectroscopy. Graphene nanosheets play an important role of governing the morphology of the electrode material and thereby enhancing the electrochemical performance of the composite electrode. The specific capacitance of 207 F/g is obtained for nickel ferrite/graphene nanocomposite, which is almost 4 times larger than pure nickel ferrite. The nanocomposite showed a stable capacitance of 95% after 1000 cycles in 1 M Na2SO4 electrolyte. Electrochemical impedance spectroscopy results indicate that graphene nanosheets reduced the charge transfer resistance on the composite electrode. The obtained results show that the nanocomposite has a great potential to be used in supercapacitor with good electrochemical performance and longer cycle stability. [ABSTRACT FROM AUTHOR]

In the present article, the synthesis of spherical hollow cobalt ferrite and application as an electrode modifier were demonstrated. The synthesis of cobalt ferrite was conducted using carbonaceous microspheres prepared from a glucose solution as a sacrificial template, followed by subsequent heat treatment. The Fe/Co molar ratio in cobalt ferrite depends significantly on the initial Fe/Co molar ratio. The Fe/Co molar ratio as 1/1 could provide the stoichiometric cobalt ferrite (CoFe2O4) with a hollow sphere structure and large saturation magnetization. The simultaneous quantification of ascorbic acid (ASA), acetaminophen (ACE), and caffeine (CAF) was performed utilizing the differential pulse anodic stripping voltammetric method with CoFe2O4 modified glassy carbon electrode. The detection limits in the linear range of 0.2–4.4 µM are 0.313, 0.267, and 0.226 µM for ASA, ACE, and CAF, respectively. This proposed method enables the simultaneous detection of ASA, ACE, and CAF in pharmaceutical formulations and beverage samples. The determined concentration of the analytes is comparable with that obtained with HPLC. [ABSTRACT FROM AUTHOR]

Cobalt ferrite (CoFe2O4) nanorods have been synthesized by a membrane-solvothermal method and a series of CoFe2O4/rGO nanocomposites with different reduced graphene oxide (rGO) weight ratios of 5%, 10%, 15%, 20%, 25% and 30% have been synthesized via ultrasonic treatment, named as CoFe2O4/rGO-1, CoFe2O4/rGO-2, CoFe2O4/rGO-3, CoFe2O4/rGO-4, CoFe2O4/rGO-5 and CoFe2O4/rGO-6, respectively. The photocatalytic activity was studied by photodegradation of malachite green (MG), and the wave absorbing performance was studied by network vector analyzer. CoFe2O4 had the function of magnetic separation, which had largely reduced the separation difficulty of photocatalyst and dye wastewater. Among all the graphenebased composites, CoFe2O4/rGO-5 has the most excellent photocatalytic performance which could eliminate about 93.48% of MG in 90 min. Even after five cycles, the photocatalytic degradation rate of MG was still above 88%, suggesting that CoFe2O4/rGO-5 is a promising photocatalyst for recyclable utilization. The wave absorption test results showed that the electromagnetic wave reflection loss of CoFe2O4/rGO nanocomposites was lower than that of pure CoFe2O4, which showed that the addition of graphene could effectively enhance the absorbing properties of materials. When the thickness of the absorbing layer was 2.5 mm, the reflection loss of the CoFe2O4/rGO-4 nanocomposite reached the maximum value of 17 GHz at -11.1 dB and the bandwidth of less than -10 dB was 2.3 GHz. [ABSTRACT FROM AUTHOR]

Seven 4-arylbenzelidene-2-((5-fluoro-1H-indol-1-yl)methyl)oxazol-5(4H)-one derivatives were synthesized by the condensation of 2-(2-(5-fluoro-1H-indol-1-yl) acetoamide) acetic acid, substituted aromatic aldehydes with acetic anhydride and sodium acetate in the presence of MgO/Al2O3 under reflux using nickel ferrite nanoparticles. Seven of the compounds are new derivatives. 2-(2-(5-fluoro-1H-indol-1-yl)acetoamide) acetic acid was obtained from 2-(5-fluoro-1H-indol-1-yl)acetyl chloride with lysine in the presence of NaOH and HCl in the ice cold solution. 2-(5-fluoro-1H-indol-1-yl)acetyl chloride can be prepared from 5-fluoro indole with chloroacetyl chloride in triethylamine and dichloromethane. The structures of the compounds were evaluated based on ¹H-NMR, 13C-NMR and LC-MS and by elemental analysis. These compounds were screened by antioxidant as well as anti-microbial activity. [ABSTRACT FROM AUTHOR]

Synthesis of Zn–Mn ferrite from spent Zn–Mn batteries using a multi-step process of bioleaching and co-precipitation represents a promising means in waste management of the spent batteries. However, the low pulp density of 1.0% in bioleaching process means a low yield of Zn–Mn ferrite. In this work, the cheap and benign Fe3+ was used to replace dangerous H 2 SO 4 or expensive Cu2+ to promote bioleaching performance of spent batteries at a high pulp density of 5.0% for synthesis of Zn–Mn ferrite for the first time. The results displayed the addition of Fe3+ greatly enhanced bioleaching of spent batteries. The extraction efficiency of Zn and Mn increased from 34.5% to 29.4% to the maximum of 85.1% and 83.2%, respectively, when the concentration of added Fe3+ increased from 0 to 5.0 g/L. The added Fe3+ motivated more generation of both Fe2+ and sulfur to promote the growth of both Leptospirillum ferriphilum and Acidithiobacillus thiooxidans , respectively, attaining a higher bioleaching rate. The electro - chemical analysis also revealed the highest J Corr of 0.571 mA cm−2 occurred when the concentration of added Fe3+ was 5.0 g/L. The addition of Fe3+ at 5.0 g/L witnessed the maximum synthesis yield of Zn–Mn ferrite (52.6 g/L). • Added 5.0 g/L Fe3+ lifts bioleaching rate of Zn and Mn from 30% to over 80%. • Added Fe3+ saw more generation of Fe2+ and S0 to promote growth of L.f and A.t. • When added Fe3+ lifted from 0 to 5.0 g/L, J Corr rose from 0.190 to 0.571 mA cm−2 • Remaining Fe3+ had no negative effect on the synthesis of Zn–Mn ferrite. • Addition of 5.0 g/L Fe3+ witnessed maximum yield of Zn–Mn ferrite (52.6 g/L). [ABSTRACT FROM AUTHOR]

The cobalt (Co2+) has been successively substituted in ZnCuFe2O4 to obtain Zn0.5−xCoxCu0.5Fe2O4 (0.0 ≤ x ≤ 0.5) ferrites by auto-combustion technique. Prior to photocatalytic degradation, all as-synthesized ferrites were characterized to study their structure, composition, morphology, magnetic and optical behavior. The shifting of tetrahedral as well as octahedral stretching peaks towards higher frequencies observed in the Fourier transform infrared spectroscopy indicates that Co2+ ion is substituted in ZnCuFe2O4. X-ray diffraction pattern confirms the formation of single-phase cubic spinel with decrease in average lattice constant from 8.3915 to 8.3224 Å with increase in Co2+ substitution. The photocatalytic performance of obtained ferrite catalyst was determined using methylene blue (MB) as model dye under visible light and direct sunlight. The degradation of MB with as-obtained photocatalyst under sunlight improves (91%) which proves the effective utilization of visible light active magnetic photocatalyst. [ABSTRACT FROM AUTHOR]

• Cobalt ferrite was synthesized via the sol-gel method with varying precursor stoichiometries. • Cation in excess shows a marked preference towards the octahedral site. • A very uncommon normal spinel configuration was observed for CoFe 2 O 4. • The Curie point of the extreme formulations differ by almost 100 °C. Spinel cobalt ferrites (CoFe 2 O 4) with varying inversion degrees were prepared via a citrate-nitrate sol-gel method. The gels, prepared with different cation stoichiometries, were dried at 110 °C, further treated at 850 °C and subjected to structural and magnetic characterization. X-ray diffractograms of the samples confirm the successful synthesis of the spinel. The synthesis conditions displayed a strong influence over the positioning of the cations in the crystal structure of these ferrimagnets. Mössbauer spectra yield inversion degrees of approximately 1.0 and 0.0 for the samples prepared with excess cobalt and excess iron, respectively. These cationic arrangements are also confirmed via Raman spectroscopy, which shows a larger splitting of the A 1g signal in the sample with the highest inversion degree. The magnetic character of the samples at room temperature does not agree with what should be expect from the net magnetic moments per unit cell. However, this phenomenon was explained by the different exchange integrals at play in each of the systems, as shown by the magnetic critical temperature of each arrangement, which differed by approximately 100 °C. The proposed pathway has proven to be an accurate method for completely switching the cationic arrangement of CoFe 2 O 4 , further enabling the application of this material in advanced magnetoresistive and spintronic devices. [ABSTRACT FROM AUTHOR]

Cobalt, nickel and zinc nanosized spinel-type ferrites (MFe 2 O 4 , M: Co2+, Ni2+ and Zn2+) were synthesized by the novel oil-in-water microemulsion method. These compounds have not been fully studied for H 2 production by the water-splitting reaction, especially those prepared by microemulsion. Through proper characterization, features like crystal structure, efficient visible light absorption, high-sorption capacity and adequate textural properties, were demonstrated for thermal treated Co, Ni and Zn microemulsion synthesized nanoferrites. These characteristics favored the visible light-driven H 2 production (monitored by gas chromatography) of MFe 2 O 4 nanoparticles dispersed in water (2% MeOH), under experimental conditions. Particularly, ZnFe 2 O 4 yielded a higher amount of H 2 (354 μmolH 2 g−1) compared to Co (128 μmolH 2 g−1) and Ni (129 μmolH 2 g−1) ferrites in an 8 h experiment, presumably due to more favorable electronic band positions. This work represents a new contribution to the hydrogen evolution studies using ferrite nanoparticles. • Crystalline spinel-type ferrites (MFe 2 O 4) nanoparticles were synthesized by the oil-in-water microemulsion method. • MFe 2 O 4 nanoparticles exhibited good photocatalyst features in terms of structure, size, surface area and optical bandgap. • MFe 2 O 4 nanoparticles are molecular hydrogen producers at studied conditions. • ZnFe 2 O 4 yielded a higher H 2 production compared with cobalt and nickel ferrites. [ABSTRACT FROM AUTHOR]

Ammonium perchlorate (APC) is the most common oxidizer in use for solid rocket propulsion systems. However its initial thermal decomposition is an endothermic process that requires 102.5 J/g. This behavior involves high activation energy and could render high burning rate regime. This study reports on the sustainable fabrication of barium ferrite nanoparticles as a novel catalyzing agent for APC oxidizer. Colloidal BaFe12O19 nanoparticles with consistent product quality were fabricated using hydrothermal processing. TEM micrographs demonstrated mono-dispersed particles of 10 nm particle size. XRD diffractogram demonstrated highly crystalline material. The synthesized colloidal BaFe12O19 particles were effectively coated with APC particles via co-precipitation using fast-crash solvent–antisolvent technique. The impact of ferrite particles on APC thermal behavior has been investigated using DSC and TGA techniques. APC demonstrated an initial endothermic decomposition stage at 142 °C with subsequent two exothermic decomposition stages at 297.8 and 452.8 °C respectively. At 1 wt%, barium ferrite offered decrease in initial endothermic decomposition stage by 42.5%. The main outcome of this study is that the two main exothermic decomposition peaks were merged into one single peak with an increase in total heat release by 19.7%. These novel features can inherit ferrite particles unique catalyzing ability for advanced highly energetic systems. [ABSTRACT FROM AUTHOR]

In this letter, a new approach to the synthesis of nickel ferrite has been performed. Nickel ferrite nanoparticles have been prepared via a straightforward method by simply heating iron-nickel tertracyanide powder (FeNi(CN)4·3H2O) in air at 400 °C for only 5 min. During the heating process, it was observed that iron-nickel cyanide powder ignites at a certain point in the material and then this ignition propagates in a wave-like manner through the rest of the mass. As the ignition front propagated through the material, an extreme expansion occurred in a way similar to musical accordion and eventually formed nickel ferrite nanoparticles. Samples were characterized using XRD, SEM, HRTEM, TGA and Raman spectroscopy. All analysis confirmed the successful formation of single phase nickel ferrite. The present method can be extended to synthesize other ferrites. The presented approach is characterized by both simplicity and scalability which makes it promising for industrial utilization. [ABSTRACT FROM AUTHOR]

In this work, flexible and free‐standing films of bio‐composite of carboxymethylated cellulose nanofibers (CMCNF) and cobalt ferrite (CFO) nanoparticles (NPs) have been fabricated using in‐situ chemical route. Control over CFO fraction (1% ‐ 25%) in CMCNF matrix was achieved by adjusting volume of the iron and cobalt precursors. Free‐standing films of CMCNF‐CFO bio‐composite were characterized using X‐ray diffraction, spectroscopic, microscopic, thermal and Magnetic measurements. The Raman and X‐ray absorption near edge spectroscopy studies confirms the formation of CFO in CMCNF matrix. The microscopic studies revealed that CMCNF fibers are decorated with CFO NPs having size of the order of ∼ 25 nm. Comparison of the thermal properties of CMCNF and CMCNF ‐CFO composites shows that thermal stability improves as CFO content increases. Finally, preliminary results on a method to create 3D patterns of CMCNF ‐CFO nanocomposite having lateral dimensions ∼1.2 μm were presented that pave the way to new uses of bio‐composites. [ABSTRACT FROM AUTHOR]

Highlights • M-type hexaferrite BaZn 0.6 Sn 0.6 Fe 10.8 O 19 was synthesized at a low sintering temperature of 900 °C. • Rietveld refinement were adapted to make investigated parameters more standard. • This M-type hexaferrite is potential candidate for the design of microwave devices such as circulator operated at Ku band. Abstract M-type barium hexaferrite (BaM) of composition BaZn 0.6 Sn 0.6 Fe 10.8 O 19 was successfully synthesized through a ceramic process. Sintering aids Bi 2 O 3 ·B 2 O 3 ·SiO 2 ·ZnO (BBSZ) were added to lower the sintering temperature. The formation of pure M phase for samples sintered at 900 °C with sufficient BBSZ was confirmed from XRD patterns analysis. Large saturation magnetization (69.02 emu/g) and relatively low magnetic anisotropy field (7.4 kOe) were obtained simultaneously when sample was synthesized with 2.5 wt% BBSZ dosage. These properties make the material suitable for applications in LTCC process. The ferromagnetic resonance (FMR) linewidth (Δ H) decreased efficiently by 719 Oe owing to the sintering aids. This M-type hexaferrite is also potential candidate for the design of microwave devices such as circulators and isolators operated at low frequencies. Meanwhile, the influences of sintering aids upon the microstructure, complex permeability and magnetic properties of M-type hexaferrite BaZn 0.6 Sn 0.6 Fe 10.8 O 19 were investigated. [ABSTRACT FROM AUTHOR]

Highlights • Cation distribution was determined in 10-nm sized Mn 0.6 Zn 0.4 Fe 2 O 4 particles. • Small clusters of Mn-Zn ferrite crystallites were coated with mesoporous silica. • The mesoporous shell was loaded with rhodamine B as a hydrophilic model compound. • The shell was sealed by a temperature-sensitive gatekeeper to control the release. Abstract Hydrothermal synthesis was employed to prepare three samples of Mn-Zn ferrite nanoparticles with the mean size of crystallites of 12–14 nm, whose compositions were accurately determined by X-ray fluorescence spectroscopy to Mn 0.82 Zn 0.21 Fe 1.97 O, Mn 0.70 Zn 0.31 Fe 1.99 O 4 , and Mn 0.62 Zn 0.41 Fe 1.97 O 4. The X-ray diffraction and SQUID magnetometry were used to determine the spinel structure and ferrimagnetic properties of the samples. AC field heating experiments were performed on particles dispersed in glycerol to evaluate the specific absorption rate. Based on the superparamagnetic behaviour and magnetic hyperthermia data, the Mn 0.62 Zn 0.41 Fe 1.97 O 4 phase was selected for further studies, including a more detailed characterization of the crystal and magnetic structure by neutron diffraction and Mössbauer spectroscopy, encapsulation into mesoporous silica, determination of the specific absorption rate of coated particles, and analysis of the porosity of the shell. Shortly, the Mn 0.62 Zn 0.41 Fe 1.97 O 4 nanoparticles were found to possess high magnetization of M (10kOe) = 48.4 emu/g at room temperature and superparamagnetic behaviour at body temperature on the timescale of magnetic measurements. The coated product was formed by clusters of ferrite crystallites with overall mean size of 52 nm encapsulated into 22 nm thick mesoporous shell and showed heating efficiency of 57 W/g(Mn + Fe) in AC field of 970 kHz and amplitude of 8 mT. The mesoporous shell provided specific surface area of 670 m2/g, and its pores of an average diameter 3 nm occupied specific volume of 0.45 cm3/g. In a a preliminary study, the silica pores were loaded with rhodamine B as a model of a hydrophilic drug and subsequently enclosed by lauric acid that served as a temperature sensitive gatekeeper. The release of the model compound to aqueous medium was determined at room temperature and 60 °C by spectrophotometric analysis. Results have shown that amount of rhodamine B in pores achieved 15 mg per gram of silica-coated ferrite cores and its release was controlled by temperature. [ABSTRACT FROM AUTHOR]

Highlights • Synthesis of monophase Mn-ferrite nanoparticles (NPs) via the hydrothermal method. • Applying of polyethylene glycol (PEG) polymer as a coating on the synthesized NPs. • Improving stability of dispersions containing the PEG-coated Mn-ferrite NPs at pH 7. • Superparamagnetic PEG-coated Mn-ferrite NPs with enhanced MRI contrast effect. Abstract In this work, manganese ferrite (MnFe 2 O 4) nanoparticles (NPs) were successfully synthesized via the hydrothermal method, and the dispersibility and the biocompatibility of the product were improved by the polyethylene glycol (PEG) polymer as a coating onto the surface of the synthesized NPs. The potential of the use of the synthesized PEG-coated NPs as contrast agents in the magnetic resonance imaging (MRI) was also investigated. The XRD results showed that the monophase MnFe 2 O 4 NPs were synthesized at the pH of 11, the temperature of 200 °C for 12 h (optimal conditions) via the hydrothermal method. The FE-SEM and TEM investigations showed that the hydrothermally synthesized NPs had a quite homogeneous size distribution with the average size of about 50 nm. The water-based dispersions of PEG-coated Mn-ferrite NPs showed the higher stability at pH 7 in comparison with the uncoated ones. The PEG-coated Mn-ferrite NPs showed a high saturation magnetization value (60 emu/g). An enhanced MRI contrast effect by the PEG-coated NPs was confirmed via the in vitro MRI study. Moreover, the cytotoxicity activity of the PEG-coated NPs on the HeLa cells demonstrated a high cell viability even at a 0.2 mg/ml of NPs after 48 h of incubation. Also, the in vitro hemocompatibility studies of the synthesized NPs showed that the PEG-coated NPs had no effect on the blood coagulation factors, and the red blood cell (RBC) count measured by complete blood count (CBC) tests in all the investigated concentration range. It can be concluded that, therefore, the hydrothermally synthesized PEG-coated Mn-ferrite NPs in this study can be good candidates as MRI contrast agents. [ABSTRACT FROM AUTHOR]

Abstract Co-Mg ferrites, Co x Mg 1 − y Fe 2 − z O 4 (x = 0.0, 0.2, 0.4, 0.6, 0.8 and 1.0, 0 < y < 0.34 and 0 < z < 0.67), were synthesized via a standard ceramic route, and the structural, morphological, magnetic properties and transmission parameter of the samples were studied. The thermal behavior of the ground powder was characterized using a differential thermal analysis technique (DTA). The XRD patterns proved the formation of single phase Mg-ferrite in the samples with "x" contents varying from 0.0 to 0.8. The sample with x = 1.0 showed two phases: a spinel Mg-ferrite and a secondary (Co,Mg)O phase. The lattice parameter and crystallite size of the samples increased remarkably by increasing the x content. The SEM images revealed that Co substitution in Mg ferrite at x = 0.2 causes the particle growth, but their growth was not significant until x = 0.8. For x = 1.0, a remarkable particle growth was again observed. A maximum bulk density of 4.94 g/cm3 was obtained for x = 0.8. Magnetic properties of the sintered samples showed an increase in coercive force up to 113 Oe by increasing Co substitution up to x = 1.0. Saturation magnetization reached a maximum value of ~45.40 emu/g at x = 0.8. Studying the microwave transmission behavior of the samples, using a vector network analyzer (VNA), indicated that by increasing Co, the transmission loss was reduced from ~ − 15 dB for x = 0.0 to less than − 10 dB for x = 0.8 in the frequency range of 8–12 GHz. [ABSTRACT FROM AUTHOR]

Single-domain manganese ferrite nanoparticles were synthesized through one-step chemical co-precipitation technique using diethanolamine which acted simultaneously as precipitating and capping agent. The synthesized nanoparticles were characterized by XRD, FTIR, TGA, EDX, FESEM and VSM. XRD pattern showed the presence of peaks corresponding to the single-phase inverse spinel structure with an average crystallite size of 59.6 nm. The average particle size determined by FESEM was 46.8 nm. In addition, the magnetic properties of the nanoparticles analyzed by VSM exhibited nearly superparamagnetic property with a high saturation magnetization of 77.31 emu/g with little coercivity (10.53 emu/g) and remanence (9.32 emu/g) at 300 K temperature. TGA and FTIR results confirmed the binding of diethanolamine onto the surface of manganese ferrite nanoparticles. The synthesized nanoparticles exhibited single crystalline phase with improved magnetic properties. [ABSTRACT FROM AUTHOR]

The present work was focused on the effect of small amounts of Dy doping on the structural and magnetic properties of Ni-Cr ferrite materials. All the ferrites possess cubic symmetry corresponding to the space group with small amounts of secondary phase DyFeO3. No regular trend in the lattice parameter a with Dy doping has been observed. Room temperature magnetisation results, obtained from Vibrating Sample Magnetometer measurements, showed a decrease in saturation magnetisation with Dy doping. Enhanced coercivity in undoped Ni-Cr ferrite is observed which was several orders of magnitude higher than that of the reported bulk material. Substitution of Dy in Ni-Cr ferrite further enhances coercivity thereby making the materials magnetically more hard. [ABSTRACT FROM AUTHOR]

Highlights • Magnetic and microwave absorption analysis of Ba (1−2x) La x Na x Fe 10 Co 0.5 TiMn 0.5 O 19. • Saturation magnetization decreases from 55.667 to 44.768 emu/g for x = 0.00 to 0.25. • RL for the sample x = 0.10 is −45.94 dB (99.997% absorption) with 8.33 GHz bandwidth. • Synthesized ferrites can be utilized in EM shielding and RAM applications. Abstract La-Na co-substituted M-type Co-Ti-Mn barium hexaferrites Ba (1−2x) La x Na x Fe 10 Co 0.5 TiMn 0.5 O 19 (0.00 ≤ x ≤ 0.25) were synthesized by conventional solid-state method. The influence of La-Na doping on the magnetic properties was investigated through VSM (vibrating sample magnetometer). The room temperature hysteresis loops show that the saturation magnetization decreases from 55.667 emu/g for x = 0.00 to 44.768 emu/g for x = 0.25 sample. To determine the complex permittivity (ε r = ε′ – iε″) and permeability (µ r = µ′ – iµ″) in 18.0–26.5 GHz frequency range, a vector network analyzer was employed. Reflection loss (RL) values were simulated from the values of ε r and µ r acquired using transmission line theory. The minimum RL obtained for the sample x = 0.10 is −45.94 dB (99.997% signal absorption) with an absorption bandwidth of 8.33 GHz for 1.3 mm sample thickness. Thus, the synthesized hexaferrites can be utilised in electromagnetic shielding and radar stealth technology applications. [ABSTRACT FROM AUTHOR]

The BaFe12-xGaxO19 (x < 1.2) hexaferrites were synthesised by usual ceramics technology. The Bi2O3 additive in the amount of 3 wt% was applied. The features of crystal structure and unit cell parameters were refined using powder X-ray diffraction at 300 K. It is shown that with the substitution level increase the parameters of unit cell monotonically decrease. The magnetisation and susceptibility versus temperature and field for these solid solutions were investigated by the vibration magnetometry method. The concentration dependence of the main magnetic parameters is constructed. It is shown that with the substitution level increase the magnetic parameters monotonically decrease. The microwave properties of the samples including the external magnetic bias field are also investigated at 300 K. It is shown that with the increase of Ga3+ concentration from x = 0.1 to x = 0.6 the frequency value of natural ferromagnetic resonance (NFR) decreases in the beginning, and at further increase in concentration up to x = 1.2 it increases again. With the increase in Ga3+ concentration, the line width of the NFR increases that indicates the increase of frequency range where there is an intensive absorption of electromagnetic radiation (EMR). At the same time, the peak amplitude of the resonant curve changes slightly. The frequency shift of NFR in the external magnetic bias field takes place more intensively for the samples with small Ga3+ concentration. It is shown the prospects of use of the Ga-substituted barium hexagonal ferrite as the material effectively absorbing the high-frequency EMR. [ABSTRACT FROM AUTHOR]

Nanocrystalline ferrites are known to be used in different applications, including industrial wastewater management. For environmental water issues, one of the most widely applied techniques is the adsorption of pollutants. The adsorption capacity of Congo red (CR) dye on different MFe2O4 (M = Co2+, Mg2+, Mn2+, Ni2+, and Zn2+) ferrites, synthesized by coprecipitation method, was determined. Specific isotherms and kinetic models were used to characterize the adsorption process. Interesting results were obtained for MgFe2O4 with adsorption capacity ranging from 39% up to 70% dependent on the initial dye concentration. Furthermore, an artificial intelligence model based on neural network was developed in order to model the adsorption rates followed by the generation of 3D adsorption rate models for each type of synthesized ferrite. These models were obtained in order to provide information about the particle‐dye system's kinetics at various initial CR concentration. Specific techniques were used to characterize the functionalized magnetic particles. The main steps for obtaining 3D adsorption map. [ABSTRACT FROM AUTHOR]

The traditional method of ferrite synthesis is based upon solid‐state reaction. The advantages of this approach include simplicity, cost effectiveness, and suitability for commercial process scaling. However, there exist shortcomings in that impurities and defects adversely affect magnetic properties. Here, iron‐depleted compositions of bismuth‐substituted yttrium iron garnet (ie Bi:YIG) were studied with emphasis placed on the impact of synthesis processing parameters upon the structure and gyromagnetic properties. It was shown that ferrimagnetic resonance linewidth experienced a minimum of 180.3 Oe (X‐band) when the sample stoichiometry was 4% depleted in iron (x = 0.2), a reduction of 29.3% from the parent compound. Concomitantly, iron depletion caused a systematic change in lattice parameter that resulted in a dilation of Goodenough‐Kanamori‐Anderson bond angles increasing exchange energy and magnetization. The substitution of Bi for Y on the dodecahedron sites altered the reaction path and decreased the activation energy effectively reducing sintering temperature. To establish a functional processing protocol, an ion diffusion model is presented to explain the demonstrated processing, structure, and performance paradigm. The Bi3+ ions dissociated from Bi2O3 crystal induce the breakage and recombination of O‐M bonds of high milling point metal oxide, formating the core‐shell structure, and promoting the low temperature sintering of yttrium iron garnet. [ABSTRACT FROM AUTHOR]

Graphical abstract The tetraalkyliron(III) complex, [Li(THF) 2 ][Fe(CH 2 Si(CH 3) 3) 4 ], has been synthesized containing modified methylene substituents that incorporate large trimethylsilyl (TMS) groups to further probe steric and electronic ligand effects in tetraalkyliron(III) complexes by increasing the electron-donating ability of the ligand while retaining steric bulk. Detailed structural and DFT studies provide insight into electronic structure and bonding of this complex compared to the previously reported analogs containing methyl and benzyl ligands. Abstract Homoleptic iron-alkyl complexes have been implicated as key intermediates in iron-catalyzed cross-coupling with simple iron salts. Tetraalkyliron(III) ferrate species have been shown to be accessible with either methyl or benzyl ligands, where the former complex is S = 3/2 and distorted square planar while the latter is a S = 5/2 distorted tetrahedral species. In the current study, a new tetraalkyliron(III) complex is synthesized containing modified methylene substituents that incorporate large trimethylsilyl (TMS) groups to further probe steric and electronic ligand effects in tetraalkyliron(III) complexes by increasing the electron-donating ability of the ligand while retaining steric bulk. Detailed structural and DFT studies provide insight into electronic structure and bonding of the four-coordinate trimethylsilylmethyl iron(III) complex compared to the previously reported analogs containing methyl and benzyl ligands. [ABSTRACT FROM AUTHOR]

Abstract The additional effect of the dynamic strain aging (DSA) on the microstructural parameters in influencing the yield strength was analyzed through comparing the difference between the experimental yield strength and the calculated value at room temperature (RT) in 9Cr-1.7W-0.1C reduced activated ferritic-martensitic (RAFM) steel samples treated under two different heat treatments. Different heat treatments leaded to the variation of the microstructural parameters of this steel. Then the contributions of these microstructural parameters and DSA on the tensile properties at elevated temperatures were studied with the modified Crussard–Jaoul (C–J) analysis based on the Swift equation. [ABSTRACT FROM AUTHOR]

Abstract Oxide dispersion strengthened (ODS) steels of Fe–9Cr– x Al (x = 0.4, 2.5, 4.5 and 8.0 wt%) have been fabricated by mechanical alloying, hot isostatic pressing and subsequent forging. Both the ferrite matrix and yttria particles were coarsened by the addition of Al. However, a bimodal structure consisting of coarse grains closely surrounded by fine grains is formed, and develops with increasing Al addition. Moreover, at the same time, nano-sized alumina particles precipitate in the interior of the bimodal ferrite grains. The tensile strength increases gradually with Al addition due to back stress strengthening combined with Orowan strengthening. The formation mechanism of the bimodal structure and intragranular precipitation of the Al added ODS steels were also discussed. [ABSTRACT FROM AUTHOR]

Abstract Metal-doped magnesium ferrite (MgFe 2 O 4) with cubic spinel structure, large specific surface area and medium saturation magnetic strength was synthesized from saprolite laterite leaching solution through hydrothermal-calcination method and used as a heterogeneous Fenton-like catalyst. The influence of reaction temperature on the catalytic process was centrally discussed based on the hydroxyl radical theory. The as-prepared MgFe 2 O 4 exhibited favorable catalytic activity for degradation of Rhodamine B (RhB), achieving 97.8% degradation efficiency of 10 mg·L−1 RhB within 300 min (90.0% degradation, 180 min) at the conditions of 45 °C, pH 6.44, 0.625 g·L−1 catalyst dosage and 1.00 vol% H 2 O 2 concentration. And the TOC removal efficiency could reach 77.8%. After five consecutive degradation cycles, the reduction of degradation and TOC removal efficiencies were <3.0% and 8.0%, respectively, suggesting the metal-doped MgFe 2 O 4 had high catalytic activity, good stability and excellent reusability. More importantly, the formed catalyst may broaden the application of saprolite laterite and provide a promising way for other natural minerals which contain transition metal elements in the treatment of organic dye wastewater. Graphical abstract Metal-doped magnesium ferrite synthesized from saprolite laterite is an effective and stable heterogeneous Fenton-like catalyst for organic dye removal. Unlabelled Image Highlights • Metal-doped MgFe 2 O 4 was synthesized from saprolite laterite. • The as-prepared MgFe 2 O 4 is an effective heterogeneous Fenton-like catalyst. • The rise of temperature could promote the formation of OH radicals in as-prepared MgFe 2 O 4 /H 2 O 2 system. • The catalyst exhibited high stability and excellent reusability. [ABSTRACT FROM AUTHOR]

Abstract Spinel and garnet nanostructured ferrites have been used for various potential applications. Single phase spinel and garnet nanoferrites have been used for different applications in many fields. Ni-Zn (Ni 0.5 Zn 0.3 Al 0.2 Fe 2 O 4) ferrite with spinel structure and YAIG (Y 2.8 Al 0.2 Fe 5 O 12) ferrite with garnet structure were synthesized using sol-gel technique. The structural, morphological and magnetic studies were done for spinel and garnet nanoferrites. X-ray diffraction (XRD), scanning electron microscopy (SEM) and vibrating sample magnetometer (VSM) were used to investigate the structural, morphological and magnetic properties of the spinel and garnet nanoferrites respectively. Single phase spinel and garnet nanocrystalline ferrites were confirmed from XRD analysis. Circular and cubic shape morphology was observed for spinel and garnet nanoferrites respectively. Static magnetic characteristics of the Al doped spinel and garnet nanoferrites (saturation, remanence, coercivity and magnetic squareness) were measured from the hysteresis loops. Dynamic magnetic properties such as initial permeability, Q factor and magnetic losses of the Al doped spinel and garnet nanoferrites were also evaluated from magnetic measurements. Spinel and garnet nanoferrites prepared at low temperature may have potential in industrial and technological applications e.g. transformers, switching, cores, filters, sea bed logging, MLCI's, microwave absorption bio medical applications and microwave frequency (C and X) band applications. Graphical abstract Image 1 Highlights • Ni 0.5 Zn 0.3 Al 0.2 Fe 2 O 4 and Y 2.8 Al 0.2 Fe 5 O 12 ferrites were synthesized using sol-gel technique. • Circular and cubic shape morphology was observed for spinel and garnet nanoferrites respectively. • Better magnetic characteristics are achieved for Al doped garnet nanoferrites. • These are suitable for MLCI's and microwave frequency (C and X) band applications. [ABSTRACT FROM AUTHOR]

Abstract For the first time, Manganese ferrite (MnFe 2 O 4) with two different catalytic and morphological properties were synthesized through the conventional and template-synthetic approaches. The typical conventionally prepared MnFe 2 O 4 particles attained nanoscaled spherical structure, and the unique structured novel MnFe 2 O 4 nano-agglomerates were conquered by the template synthesis. The templates of MnCO 3 made MnFe 2 O 4 to attain the nano-agglomeric structure with the abundant electroactive surface area and copious catalytic sites, which were confirmed through the structural, morphological, elemental, and electrochemical investigations. By the recent reports, the supercapacitor and heavy metal detection properties of MnFe 2 O 4 were recognized. Therefore, both the MnFe 2 O 4 nanospheres (NSs), and MnFe 2 O 4 nano-agglomerates (NAs) were applied for the detection of Hg(II) ions in real samples, and also for the supercapacitor applications. Both the materials exhibited moral parameters in electrochemical sensing and supercapacitor applications, but the results obtained for the MnFe 2 O 4 NAs is quite high (LOD: 0.14 nM and Specific capacitance: 1283 F/g at 5 mV/s) when compared to the NSs. Finally, the MnFe 2 O 4 NAs was employed to be an active participant in supercapacitor and also to detect Hg(II) ions in seafood and industrial wastewater samples. Graphical abstract Image 1 Highlights • For the first time, unique structured novel MnFe 2 O 4 nano-agglomerates were conquered by the template synthetic approach. • The typically synthesized MnFe 2 O 4 nanospheres were compared with the template synthesized nano-agglomerates. • As a comparison study, both the MnFe 2 O 4 nanospheres and nano-agglomerates were applied for the detection of Hg(II) ions, and also for the supercapacitor applications. • The results obtained for the MnFe 2 O 4 nano-agglomerates is quite high (LOD: 0.14nM and Specific capacitance: 1283 F/g at 5 mV/s) on compared to the nanospheres. [ABSTRACT FROM AUTHOR]

Mössbauer spectroscopy, as well as magnetic measurements and transmission electron microscopy, was employed to investigate the particle size and magnetic and structural properties of Co–Ni spinel ferrites synthesized via a succession of chemical co-precipitation, hydrothermal treatment, and etching in hydrochloric acid (HCl). A maximum coercive force of 519 kA/m and saturation magnetization of $60.4~\text {A}\cdot \text {m}^{2}$ /kg were obtained after etching in HCl with a concentration of 4 mol/L. At room temperature, the samples obtained after co-precipitation showed partially paramagnetic behavior; however, this effect disappeared in the Mössbauer spectra at liquid He temperature. The area ratio of the Fe ions at A-sites and B-sites changed as particle size was increased, indicating that the cation distribution is changed as a result of the size and synthesis method. After the final stage of synthesis, i.e., etching, the degree of inversion was found to be 1, indicating that the structure is a completely inverse spinel. It is expected that the cation distribution, especially the increase of Co2+ in the octahedral site, produces a higher magnetocrystalline anisotropy and thus higher coercivity. [ABSTRACT FROM AUTHOR]

Activated carbons from peach stones were prepared and tested as a host matrix of nanodispersed copper, manganese and zinc ferrites. The ferrite active phase was deposited by impregnation using solutions containing respective nitrates salts in an ultrasound bath. X-ray diffraction, Mössbauer spectroscopy, nitrogen physisorption and catalytic tests in WGS and CO-PROX reactions were applied to investigate their characteristics. The XRD and Mössbauer results revealed that a ferrite phase with spinel structure was present in the materials obtained. The presence of superparamagnetic ferrite particles of a size under 10 nm was evident from Mössbauer spectra. The BET surface area of activated carbon support was 945 m2/g. It decreased slightly after the active spinel phase deposition. The measured WGS catalytic activity of the samples followed the line: CuFe2O4/ACP > MnFe2O4/ACP = ZnFe2O4/ACP. This result could be explained with the well-known properties of copper-based catalysts referring to a very high activity at low temperature values. The activity in PROX reaction was very low for all samples studied. The copper ferrite showed a higher catalytic activity than that of manganese and zinc ferrites in PROX reaction. [ABSTRACT FROM AUTHOR]

Six samples consisting of polypyrrole (PPy), pure NiFe2O4 ferrite, and their composites at ratio of 1:4 (PF1), 1:2 (PF2), 3:4 (PF3), and 1:1 (PF4) have been prepared by a coprecipitation method and their structural, electrical, dielectric, and magnetic properties measured experimentally. The direct-current (DC) resistivity was enhanced with increasing ferrite content, while the dielectric constant and loss decreased. The magnetic properties of all the composites and the ferrite revealed a narrow loop, confirming their soft nature. The saturation magnetization, remanence, and coercivity values increased with increasing ferrite content. The obtained parameter values suggest that such materials might be suitable for use in high-frequency applications. [ABSTRACT FROM AUTHOR]

Copper cadmium ferrite nanoparticles with diameters less than 30 nm were prepared and investigated in terms of gas sensitivity. The crystal structure and surface morphology were examined using X-ray diffraction, scanning electron microscopy (SEM), elemental mapping, and transmission electron microscopy (TEM), respectively. The X-ray analysis showed the formation of the copper cadmium ferrite phase. SEM images also displayed surface morphologies and pores (active sites) of copper cadmium ferrite nanoparticles. The TEM image confirmed the nanoscale dimensions of this ferrite. The crystallite size of copper cadmium ferrite nanoparticles found to be near 9 nm. Sensitivity properties of this ferrite were investigated for seven gas types in an isolated box. The seven gas types tested in this project were ethanol, methanol, N, N-Dimethyl formamide, ammonia, acetonitrile, acrylonitrile, and acetone. Among these samples, the acrylonitrile sample at 350 °C had the best sensitivity performance. [ABSTRACT FROM AUTHOR]

In this study, BiFeO 3 (BFO) nanoparticles were synthesized via the sol–gel route and BFO/nitrogen-doped graphene (NG) nanocomposites (BFO/NG, NG: 1%, 2%, 3%, 4%, 5%, and 6%) were prepared by dispersing the BFO nanoparticles and NG in ethanol solution, before thermal drying. The structural and morphological properties of the pure BFO nanoparticles, NG, and BFO/NG nanocomposites were studied by X-ray diffraction, scanning electron microscopy (SEM), and transmission electron microscopy. The average crystallite size of the BFO nanoparticles was 57 nm. The SEM observations demonstrated that the BFO nanoparticles were well anchored on the NG. The photocatalytic activities of the as-synthesized samples were calculated based on the degradation of methyl orange under simulated sunlight irradiation. The BFO/NG nanocomposites exhibited enhanced photocatalytic activity compared with the pure BFO nanoparticles. The enhanced photocatalytic performance was attributed to the efficient transfer of photogenerated electrons from the BFO nanoparticles to NG, thereby leading to the increased availability of h + for the photocatalytic reaction. Furthermore, hydroxyl (⋅OH) radicals were detected using the photoluminescence technique with terephthalic acid as a probe molecule and they were generated on the irradiated pure BFO nanoparticles and BFO/NG nanocomposites. [ABSTRACT FROM AUTHOR]

Sol-gel autocombustion method using glycine as fuel and complexing agent was utilized to synthesize nanocrystalline Mg 1-x Cd x Fe 2 O 4 (x = 0–0.8) ferrites. An increase in adiabatic flame temperature with x during the combustion reaction was demonstrated, based on the thermodynamic calculations. The X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) results confirmed that a single-phase spinel structure in all samples is formed at a remarkably lower temperature and with a larger production rate compared to the standard ceramic and other wet-chemical methods. Crystallites growth from 98 nm to 320 nm, enhanced X-ray density and a linear increase in both theoretical and experimental lattice constants, with comparable values were observed with introduction of cadmium. Analysis of the XRD patterns, using the Bertaut method along with a detailed Rietveld analysis reflected a different cations distribution and evolution of some structural parameters with cadmium, compared to the earlier studies. The Field-emission scanning electron microscopy (FESEM) results showed that the average particle size of the synthesized ferrites increases from 161 to 520 nm for x = 0 to x = 0.8, respectively. The magnetic measurements revealed that the saturation magnetization ( M s ) initially increases and reaches the maximum value of 46 A m 2 kg −1 at x = 0.2, and subsequently decreases, while the coercivity ( H c ) and remanent magnetization ( M r ) continuously decline with x values. The present magnetic results for x = 0.0 − 0.4, show a noticeable improvement in magnetic softness compared to previous researches on the Mg-Cd ferrites obtained by other chemical methods. [ABSTRACT FROM AUTHOR]

La-Zn substituted Ba2Co2Fe12O22 (Co2Y) hexagonal ferrite was synthesized using a conventional solid-state method with composition Ba2−xLaxCo2Fe12−xZnxO22, where x equals 0.0, 0.1, 0.3 and 0.5. The phase formation behavior and changes in the crystal structure of the substituted ferrite were investigated using x-ray diffraction (XRD) analysis. Accurate lattice parameters were evaluated through Rietveld refinement of the XRD pattern. XRD, as well as energy dispersive spectral analysis, showed the formation of a lanthanum iron oxide phase in x = 0.3 and 0.5 compositions. There was a small increase in unit cell volume with the substitution. The microstructural analysis showed a decrease in grain size with increasing substitution. The magnetic properties; Ms, Mr, and Hc of the ferrite were measured and found to increase with increasing substitution. Permittivity and permeability were measured and found in the range 10-16. It can be concluded that the La-Zn substitution was an effective method for improving magnetic and dielectric properties of the Co2Y ferrite. [ABSTRACT FROM AUTHOR]

The structural and magnetic properties of lithium ferrite nanoparticles synthesized through the solution combustion route at different fuel to oxidizer ratio are studied using different techniques. Powder X-ray diffraction studies show that the fuel to oxidizer ratio is a critical parameter that determines the phase purity and degree of order of the samples. Magnetic studies show that the saturation magnetization and coercivity are comparable to those reported for lithium ferrites prepared using other methods. Saturation magnetization of Li0.8 sample at room temperature is 60 emu/g and is close to the bulk value. The hyperfine parameters obtained from the Mössbauer spectra of Li0.6 and Li0.8 also match the reported values of phase pure samples. Mössbauer spectra of samples prepared at stoichiometric and fuel rich conditions show the presence of Fe 2+ cations in the ferrite phase, indicating that a reducing environment which reduces Fe 3+ to Fe 2+ ions is created as the fuel to oxidizer ratio is increased. The variation in the structural and magnetic properties of the samples, combined with TGA and FTIR studies, shows that the fuel lean condition is more appropriate for the direct formation of single phase lithium ferrite nanoparticles. [ABSTRACT FROM AUTHOR]

A series of paramagnetic ionic liquids (PILs) based on N , N ′-bis(alkyl)imidazolium bromotrichloroferrate(III), [(C n ) 2 Im][FeCl 3 Br] (Im = imidazole; C n  = ethyl, butyl, hexyl, octyl, decyl, dodecyl), was prepared and compared against the more traditional [C n C 1 Im][FeCl 3 Br] (C 1  = methyl) analogs. Both series were extensively characterized by physical, chemical, and computational methods including differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), spectroscopy (FTIR and UV‐vis-NIR), magnetic susceptibility, surface tensiometry, density, and viscosity. The X-ray crystal structure of [(C 12 ) 2 Im][FeCl 3 Br] was also obtained. Notably, all ionic liquids prepared in this study show short-term thermal stabilities exceeding 300 °C in air and have melting points equal to or lower than 25 °C, which is surprisingly low for ionic liquids containing symmetrical cations. In addition, all presented ionic liquids have relatively low viscosities allowing for easier transitioning into applications. Physical property trends are discussed. [ABSTRACT FROM AUTHOR]

Chitosan-coated cobalt ferrites were synthesized by wet ferritization method through two different approaches. The nanostructured chitosan-coated cobalt ferrites were characterized by: X-ray diffraction (XRD), scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM/HR-TEM), thermal analysis, infrared spectroscopy (IR) and Mössbauer spectroscopy. X-ray diffraction patterns confirmed the formation of CoFe2O4 cubic spinel structure with an average crystallite size of 1.75 and 5.5 nm, respectively. Mössbauer spectra consist in a central quadrupole pattern. The deconvolution in the hypothesis of Lorentzian line shape evidences the prevailing presence of Fe3+ ions at the nanoparticle surface. The antimicrobial activity of chitosan-coated cobalt ferrites against Gram-positive and Gram-negative bacteria, as well as fungal strains was investigated. Based on the results, chitosan-coated cobalt ferrites are thought to be suitable candidates for the development of novel anti-biofilm agents. [ABSTRACT FROM AUTHOR]