Search

A series of Co/Cu co-doped ZnO epitaxial films has been grown on sapphire substrates to investigate the possibilities of tailoring the magnetic properties in functional ZnO-Co/Cu nano-composites. The growth was performed using reactive magnetron sputtering varying the oxygen partial pressure to tune the incorporation of the dopants and the resulting valence state. At high oxygen pressures, Co2+ is formed and the resulting magnetic properties are very similar to phase pure paramagnetic Co-doped ZnO samples. However, the formation of a secondary CuO phase reduces the overall structural quality of the layers and virtually no substitutional incorporation of Cu2+ in ZnO could be evidenced. At low oxygen pressures, a significant fraction of metallic Co and Cu forming nanometer-sized superparamagnetic precipitates of a Co/Cu alloy can be evidenced which are embedded in a ZnO host matrix. [ABSTRACT FROM AUTHOR]

Copyright of Diyala Journal for Pure Science is the property of Republic of Iraq Ministry of Higher Education & Scientific Research (MOHESR) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The paper presents the particularities of the manufacture of nanopowders that can be used in industry by conducting a study of the magnetic properties of nanocomposite materials. The research was carried out within the INCDIE ICPE-CA in collaboration with the Naval Academy in Constanța and with the Polytechnic University of Bucharest. Depending on the mechanical, electrical and magnetic characteristics of the nanoparticles, their area of application is analyzed. The paper presents methods of chemical synthesis of magnetic nanoparticles and their importance due to their homogeneity, size control and particle distribution. Many magnetic nanoparticles can be synthesized using precipitation reactions in aqueous solutions. The discovery of metal-carbonyl complexes by thermolysis results in nanopowders. [ABSTRACT FROM AUTHOR]

Highlights • Partial decomposition of SrAl 2 M hexaferrite in Ar/H 2 atmosphere. • Formation of SrAl 2 M/FeCo 2 nanocomposites through reduction of CoFe 2 O 4. • Formation of SrAl 2 M/Fe nanocomposites through borohydride reaction. • Hysteresis behavior of nanocomposites shows absence of exchange coupling. Abstract Hard/soft magnetic nanocomposites were synthesized with SrAl 2 Fe 10 O 9 as hard and CoFe 2 or Fe as soft magnetic phase. Al-substituted hexaferrite powder with 250 nm particle size is stable in Ar/5%H 2 atmosphere at 315 °C, contrary to non-substituted hexaferrite. Annealing at T > 400 °C under these conditions leads to formation of Fe metal besides remaining hexaferrite phase. Such nanocomposites exhibit hysteresis loops with increased M s. Alternative routes to synthesize nanocomposites were also explored. A mixture of hexaferrite and nanosize CoFe 2 O 4 particles was annealed at 315 °C in Ar/5%H 2 atmosphere. The spinel ferrite particles were reduced to CoFe 2 alloy. Alternatively, soft iron nanoparticles were deposited onto the Al-substituted hexaferrite particles via a sodium borohydride reaction. Annealing at 315 °C in Ar/5%H 2 gives a hexaferrite/Fe composite powder. Room temperature hysteresis loops, however, exhibit a multiple-phase reversal behavior. [ABSTRACT FROM AUTHOR]

Abstract Nanocomposites composed of magnetic and dielectric materials are suitable for high performance electromagnetic wave absorbers due to their great impedance matching. In this work, the microwave absorbing properties of Fe 3 O 4 BaTiO 3 composites were investigated over a frequency range of 1–18 GHz Fe 3 O 4 BaTiO 3 composites present significantly enhanced microwave absorption performance compared with BaTiO 3. For the optimal Fe 3 O 4 (x) BaTiO 3 (1-x) (x = 0.8) composite, the reflection loss (RL) could reach −47.4 dB at 12.26 GHz with a matching thickness of 2.2 mm, the bandwidth below −10 dB is 5.0 GHz, which is six times higher than BaTiO 3. The broadened absorption bandwidth is resulted from better impedance matching. This results show that Fe 3 O 4 BaTiO 3 composites can be used as an excellent microwave absorption materials with strong absorption and broad bandwidth. [ABSTRACT FROM AUTHOR]

Highlights • Synthesis of CoFe 2 O 4 @ BiFeO 3 and BiFeO 3 @ CoFe 2 O 4 by co-precipitation method. • Core-shell structure of developed nanocomposites is identified by HRTEM. • Highest magnetic and dielectric properties are observed in CoFe 2 O 4 @ BiFeO 3 sample. • Magnetoelectic coupling is observed in developed core-shell nanocomposites. • Interchanging core and shell position of developed materials is novelty of our work. Abstract Nano-sized CoFe 2 O 4 (CFO), BiFeO 3 (BFO) and their core-shell composites BFO@CFO and CFO@BFO were synthesized by chemical co-precipitation method. X-ray diffraction pattern confirmed the crystallinity and phase formation of bare CFO, BFO and their core-shell composites. Morphology and core-shell nature of these nanoparticles is justified by field emission scanning electron microscopy (FESEM) and high resolution transmission electron microscopy (HRTEM). Magnetization curve showed the weak ferromagnetic behaviour of BFO. Typical ferrimagnetic behaviour is shown by bare CFO and core-shell nanocomposites. The value of maximum magnetization, remanence magnetization and coercivity of CFO@ BFO were found to be greater than the BFO@ CFO. Also, CFO@ BFO showed the highest value of dielectric constant in the frequency range of 104–106 Hz. Dielectric constant versus temperature curve of BFO and core-shell composites exhibit incongruity close to the antiferromagnetic transition temperature (370 °C) of BFO indicating presence of magnetoelectric (ME) coupling. [ABSTRACT FROM AUTHOR]

Highlights • Colloidal nanocomposites of iron oxide-SiO 2 -TiO 2 -metalloporphyrins were prepared. • The superparamagnetic composites are active photocatalysts under visible light. • Effects of metals on the photocatalytic activities were investigated. • The composites exhibits bactericidal activity under visible light activation. Abstract Multifunctional photocatalyst system of meso-tetra(4-carboxyphenyl)porphyrin (TCPP) with different metal centers [Mn(II), Fe(III), Cu(II), Zn(II) and metal-free] adsorbed on titania-silica-iron oxide magnetic photocatalyst nanocomposites (TSI) that united superparamagnetic behavior and high photoactive activity under visible light irradiation have been prepared. The superparamagnetic nanocomposites have been characterized and analyzed using UV-visible absorption spectroscopy, X-ray diffractometry (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), and X-ray photoelectron spectroscopy (XPS). The results showed that copper(II)tetra(4-carboxyphenyl)porphyrin -sensitized titania-silica-iron oxide nanocomposites (CuTCPP-TSI) can effectively degrade methylene blue (MB) and kill Escherichia coli (E. coli) under irradiation with an incandescent lamp. The magnetic photocatalysts could be used at least four times without regeneration. Therefore, the CuTCPP-TSI nanocomposites can be applied in catalytic photodegradation and used for magnetically-guided antibacterial applications. [ABSTRACT FROM AUTHOR]

Highlights • Magnetic mesoporous silica nanocomposites with peroxy groups were obtained. • These heterogeneous oxidizing agents were used in epoxidation of vinyl acetate. • Magnetic response facilitated the separation and recycle of the materials. Abstract Peroxy-functionalized magnetic mesoporous silica (MMS-PA) composites containing magnetic nanoparticles (MNPs) and peroxy acids were synthesized to be used as an easily reusable heterogeneous oxidant for the epoxidation of alkenes. The presence of peroxy acid functional groups on the composites was confirmed by Fourier transform infrared spectroscopy (FTIR). Transmission electron microscope (TEM) of the MMS-PA composites revealed the irregular structure of porous silica attached with the MNPs. The surface area of the MMS-PA was calculated to be 1089 m2 g−1, which is significantly lower than that of the starting mesoporous silica. As measured using vibrating sample magnetometer (VSM), MMS-PA exhibited saturation magnetization of 0.12 emu/g, indicating that the heterogeneous oxidant could respond to an external magnet. The oxidizing activity of the synthesized MMS-PA composites was investigated using vinyl acetate as a model substrate; the yields of the corresponding epoxide products were measured using nuclear magnetic resonance (NMR) spectroscopy. At room temperature, the freshly prepared MMS-PA gave 52% yield of the product, and the yield decreased only slightly to 47% for the recycled MMS-PA obtained by reactivating the recovered MMS-PA with concentrated H 2 O 2 in acidic medium. [ABSTRACT FROM AUTHOR]

Highlights • Some flexible and waterproof polymeric sheets are developed for EM wave absorption. • Novel polymeric matrix promotes the mechanical and EM wave absorbing properties. • Because of the novel matrix, the amount of fillers is reduced, significantly. • The thickness and density of the sheets are 1 mm and ≈2 gr/cm3, respectively. • The sheets show a remarkable thermal stability and the elongation. Abstract In this work, electromagnetic (EM) wave absorbing properties of polypyrrole/silicone rubber (PP-SI) filled nano-carbon and carbonyl iron (CI) nanocomposites have been investigated in the X-band. The PP-SR matrix was provided by the incorporation of polypyrrole and liquid silicone rubber in the ratio of 10:90. The PP-SR serves not only as a matrix but also promotes the flexibility and EM wave absorption of the nanocomposite sheets. In the present research, the chemical, morphology, thermal, wetting, absorption, and mechanical properties of the EM wave absorber sheets are investigated. The EM wave absorber sheet with 3 wt% nano-carbon and 37 wt% CI and a thickness of 1 mm, exhibits a minimum reflection loss around −13 dB at 10.27 GHz. The absorber sheet with an elongation of 520% could be qualified as a superior elastic sheet. The specimen represents higher thermal stability compared with pure SR, and the contact angle of the sheet proved that their surface should be hydrophobic. [ABSTRACT FROM AUTHOR]

Annealing effects on microstructure and magnetic properties of (NdPr)9.5(FeNbCo)79.5(BC)11 ribbons were investigated. It was observed that Nd2Fe14B and Fe3B phases were directly formed at low spinning speed. Then, the alloys transformed to an amorphous state at a speed of 20 m/s. Annealed at 700 ∘C for 10 min, the amorphous alloys as-quenched at 20 m/s crystallized into a nanocomposite composed of Nd2Fe14B and α -Fe phases. The formation of Fe3B phases was inhibited. The magnetic properties firstly increased and then decreased with the increasing of annealing time. The optimum magnetic properties were achieved in the alloys annealed at 700 ∘C for 10 min. The corresponding coercivity, remanence, and the maximum energy product was 427.5 kA/m, 0.94 T, and 101.2 kJ/m3, respectively. In addition, fine and uniform grains were formed. The average grain size was 10 nm. [ABSTRACT FROM AUTHOR]

Abstract Nowadays, the detection and removal of environmental pollutants are particularly important, owing to their harmful influence on human beings' health. Specifically, metal-organic frameworks (MOFs) as the hot materials with great potential have been widely employed as adsorbents for pollutants removal, as well as matrixes for mass spectrometry detection. In this work, magnetic Zr-based MOF (denoted as Fe 3 O 4 @PDA@ZrMOF) with outstanding properties, such as low background interference, high desorption/ionization efficiency, excellent signal reproducibility, ultrahigh surface area and strong magnetic responsiveness, was synthesized by a modified thermal annealing method. The Fe 3 O 4 @PDA@ZrMOF not only can be utilized as adsorbent towards small molecules by π-π stacking interaction between nitrophenols and ZrMOF, but also can serve as a matrix for detection of small molecules under the negative ion mode of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). As a result, with the use of Fe 3 O 4 @PDA@ZrMOF, the detection limits of 4-nitrocatechol and 4-nitroguaiacol were estimated to be about 68 μg/ml and 25 μg/ml, respectively. In addition, enrichment of nitrophenols from PM 2.5 was investigated. The detected mass concentrations of 4-nitrocatechol and 4-nitroguaiacol in collected PM 2.5 samples were 0.11 ng/m3 and 0.15 ng/m3, respectively, indicating the highly efficient enrichment performance of Fe 3 O 4 @PDA@ZrMOF for low-abundance nitrophenol compounds in the environment. Graphical abstract fx1 Highlights • Fe 3 O 4 @PDA@ZrMOF was used to enrichment and detection of environmental pollutants. • Fe 3 O 4 @PDA@ZrMOF which could serve as adsorbent and matrix simultaneously, we introduced it into negative ion of MALDI-TOF MS system for the analysis and detection of environmental pollutants. • Successful enrichment and detection of environmental pollutants from PM 2.5. [ABSTRACT FROM AUTHOR]

Abstract Development of a sensitive detection method for the reliable screening of widely used organophosphorus (OP) toxins is a crucial request to control their side-effects. Herein, a novel fluorometric assay based on the acetylcholinesterase (AChE) inhibited enzymatic activity and the new peroxidase-like Fe 3 O 4 nanoparticles@ZIF-8 composite (Fe 3 O 4 NPs@ZIF-8) was developed for the determination of OPs. Magnetic Fe 3 O 4 NPs were encapsulated into ZIF-8 and the high mimetic activity of produced composite was assessed on the oxidation of substrates. This observation was applied to the rapid detection of diazinon as a model OP compound. The sensing tool contains AChE and choline oxidase (CHO) enzymes, peroxidase colorimetric or fluorometric substrate, and Fe 3 O 4 NPs@ZIF-8 as the catalyst. In the presence of mimic Fe 3 O 4 NPs@ZIF-8, the generated H 2 O 2 from the enzymatic reactions of acetylcholine is decomposed to hydroxyl radicals. The radicals oxidize the peroxidase substrates to generate a detectable signal. However, due to the inhibition effect of OPs on the enzymatic activity of AChE, lower H 2 O 2 amounts are produced in the presence of diazinon. Using the fluorometric detection system, the generated signal is decreased proportionally by increasing diazinon concentration in the range of 0.5–500 nM. The limit of detection was obtained 0.2 nM. Consequently, the usage of high performance peroxidase-mimic Fe 3 O 4 NPs@ZIF-8 provided a sensitive bio-assay with a potential to be applied as screening tool for toxic OP compounds. The developed assay was successfully applied for the determination of diazinon in water and fruit juices. Graphical Abstract Sensitive assay for the detection of organophosphorus toxins based on the acetylcholinesterase (AChE) inhibited enzymatic activity and new peroxidase-like Fe 3 O 4 nanoparticles@ZIF-8 composite. Unlabelled Image Highlights • Encapsulation of magnetic Fe 3 O 4 nanoparticles into ZIF-8 frameworks • Colorimetric and fluorometric proving of mimetic activity of Fe 3 O 4 NPs@ZIF-8 • Production of H 2 O 2 by acetylcholinesterase and choline oxidase enzymatic activity • Lower gaining H 2 O 2 by diazinon inhibition effect on acetylcholinesterase activity • Sensitive sensing of diazinon with detection limit of 0.2 nM [ABSTRACT FROM AUTHOR]

The magnetic properties of various families of nanocomposite materials containing nanoparticles of transition metals or transition-metal compounds are reviewed here. The investigated magnetic nanocomposites include materials produced either by dissolving a ferrofluid containing pre-formed nanoparticles of desired composition and size in a fluid resin submitted to subsequent curing treatment, or by generating the nanoparticles during the very synthesis of the embedding matrix. Two typical examples of these production methods are polymer nanocomposites and ceramic nanocomposites. The resulting magnetic properties turn out to be markedly different in these two classes of nanomaterials. The control of nanoparticle size, distribution, and aggregation degree is easier in polymer nanocomposites, where the interparticle interactions can either be minimized or exploited to create magnetic mesostructures characterized by anisotropic magnetic properties; the ensuing applications of polymer nanocomposites as sensors and in devices for Information and Communication Technologies (ICT) are highlighted. On the other hand, ceramic nanocomposites obtained from transition-metal loaded zeolite precursors exhibit a remarkably complex magnetic behavior originating from the simultaneous presence of zerovalent transition-metal nanoparticles and transition-metal ions dissolved in the matrix; the applications of these nanocomposites in biomedicine and for pollutant remediation are briefly discussed. [ABSTRACT FROM AUTHOR]

The main purpose of this study is to synthesize and investigate the structural, magnetic and optical features of ZnFe 2 O 4 -ZrO 2 mixed metal oxide nanocomposite. ZnFe 2 O 4 -ZrO 2 nanocomposite with different ratios was prepared by a simple and low cost hydrothermal method. The samples were characterized with the aid of Fourier Transform Infrared spectroscopy (FTIR), X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Dynamic Light Scattering (DLS), Inductively coupled plasma-optical emission spectroscopy (ICP-OES), BET measurements and UV–Vis spectroscopy. The X-ray diffraction study showed that the crystalline structure of ZnFe 2 O 4 and ZrO 2 nanoparticles and ZnFe 2 O 4 -ZrO 2 nanocomposites were well-formed. FTIR Spectroscopy and SEM images further confirmed the complete formation of zinc ferrite and zirconium oxide crystalline structure with nano spherical morphology. Moreover, the particle size of the nanocomposites was between 14 and 30 nm, estimated by DLS analysis. The highest saturation magnetization (Ms) (27 emu/g) was achieved for ZnFe 2 O 4 -ZrO 2 nanocomposite with (3:1) ratio with M r and H c values of 0.17 (emu/g) and 3.02 (Oe), respectively. Moreover, optical studies indicated that addition of narrow band gap ZnFe 2 O 4 nanoparticles could effectively reduce the band gap and shift the excitation wavelength of the nanocomposite to visible light. [ABSTRACT FROM AUTHOR]

Carbon-based catalysts have attracted high attention since they are greener and cheaper, while magnetic nanomaterials are very useful in environmental application because of the easy recovery and operation given by the magnetic separability. Therefore, graphitic carbon nitride modified magnetic carbon nanocomposites Fe 3 O 4 @C/g-C 3 N 4 was prepared herein for the first time as a new carbon-based catalyst for the activation of peroxymonosulfate (PMS). The catalytic properties of Fe 3 O 4 @C/g-C 3 N 4 in activating PMS for the degradation of Acid Orange 7 (AO 7), a model organic pollutant, were investigated. AO 7 degradation efficiency was significantly enhanced after modification of Fe 3 O 4 @C with g-C 3 N 4 , and the composite Fe 3 O 4 @C/g-C 3 N 4 from loading of 5 wt% g-C 3 N 4 and calcined at 300 °C for 30 min exhibited the best performance. AO 7 could be efficiently decolorized using the “Fe 3 O 4 @C/C 3 N 4 (5%) + PSM” system within the pH range of 2–6, and 97% of AO 7 could be removed in 20 min without pH adjustment (pH = 4). Radical quenching and EPR studies confirmed that both sulfate and hydroxyl radicals produced from PMS activation were the active species responsible for the oxidation of AO 7. The degradation mechanism was suggested based on the experimental results and XPS analyses. It was proposed that the C O groups on the carbon surface of Fe 3 O 4 @C rather than the C O in g-C 3 N 4 played a key role as the active sites for PMS activation. The catalyst was magnetically separable and displayed good stability and reusability, thus providing a potentially green catalyst for sustainable remediation of organic pollutants. [ABSTRACT FROM AUTHOR]

We have investigated strain mediated magnetoelectric (ME) coupling and impedance properties in 0.5Zn 0. 3 Ni 0. 7 Fe2O4–0.5HoMnO3 nanocomposites at room-temperature. The ME voltage is measured in both longitudinal and transverse direction at a frequency of 173 Hz. The impedance, real and imaginary parts of impedance and dielectric constant have been carried out in presence of DC magnetic field. With the application of magnetic field, slight decrease in dielectric constant has been observed. The impedance, real and imaginary parts of impedance are found to increase with the increase in the applied magnetic field. Nyquist plots have been fitted using three parallel combinations of resistances–capacitance circuits. Fitted parameters show the dominant role of grain boundaries, grains and interface of two types of grains of the sample. [ABSTRACT FROM AUTHOR]

The realization that the observed kinetic coefficient ( k o b s ) varies with time in most real-time adsorption system, as against the constant value conceived in the most widely-applied adsorption kinetic models, have attracted much attention in recent time. Understanding the factors that control the extent/degree of time dependency (otherwise known as fractal-like kinetics), is therefore central in taking manipulative advantage of this phenomenon in critical adsorption applications. This study therefore deployed non-fractal-like and fractal-like kinetic approach to study the adsorption of tetracycline on monodispersed starch-stabilized magnetite nanocomposite (MSM). MSM was synthesized by in-situ coprecipitation of magnetite in the presence of starch, and successfully characterized with classical solid-state techniques. Isotherm studies indicated that MSM has heterogenous surface adsorption sites. Equilibrium and kinetic data indicated the existence of π-cation interaction as the underlying mechanism, while pH study revealed that tetracycline was adsorbed in its zwitterion form. Though the non-fractal kinetic models exhibited some level of relevance in explaining the tetracycline adsorption interactions, the best fitting of the fractal-like pseudo second order model to the adsorption kinetic data, indicated that the real-time adsorption kinetics occurred in fractal-like manner. The study also revealed that the degree of time dependency of k o b s had negative correlation with the initial tetracycline concentration. Apart from developing a low-cost strategy for addressing tetracycline water pollution, the result of this study serves a positive step towards gaining manipulative control of adsorption mechanism in potential application of MSM for targeted drug delivery and controlled release of tetracycline antibiotics. [ABSTRACT FROM AUTHOR]

We prepared FeCo/SiO2 thin films through depositng initial materials on various thickness Cu seed layers by sol-gel spin-coating and magnetron-sputtering methods. As-prepared composite films were reduced in hydrogen to induce texture growth. Structure, magnetic property, and surface topography of the films were characterized by X-ray diffraction (XRD), vibrating sample magnetometer (VSM), and atomic force microscopy (AFM). These experimental data indicate that the ratio values of I(200)/I(110) of the thin films are all larger than 1 for all the samples, indicating that FCC-copper is in favor of promoting (200) FeCo texture, but more thickness will reduce this advantage. Cu underlayers can also promote the out-of-plane magnetic anisotropy of the films. [ABSTRACT FROM AUTHOR]

In this paper, free vibration analysis of sandwich composite micro-beam (SCMB) subjected to multi physical fields is investigated using the sinusoidal shear deformation beam theory and modified strain gradient theory (MSGT). SCMB is made of five smart layers including a piezomagnetic core, two piezoelectric layers and nanocomposite facesheets which is rested on Winkler-Pasternak substrate. Due to magnetic and electric properties of SCMB, it is exposed to multi physical fields. The size-dependent governing equations of motion are derived using Hamilton’s principle and solved in a Navier-type sense. Finally, the effects of various parameters such as length to thickness ratio, volume fraction of carbon nanotubes, magneto-electrical loadings and foundation parameters on dimensionless frequency of SCMB are studied. The results of present work can be used to optimum design and control of micro-magneto/electro-mechanical devices. [ABSTRACT FROM AUTHOR]

Highly anisotropic SmCo 5 single crystal particles are promising candidates for high-density data storage and building nanocomposite permanent magnets with large maximum energy product. Previously, nanocrystalline SmCo 5 particles obtained by calciothermic reduction exhibit low magnetic energy product due to magnetic isotropy caused by severely agglomerated equiaxial particles. In this study, we report a new strategy to fabricate highly anisotropic SmCo 5 nanochips by reductive annealing of precursors with a special designed morphology. The precursors containing single crystal Co(OH) 2 nanoflakes and crystalline Sm(OH) 3 nanorods were synthesized by a hydrothermal process, and converted into SmCo 5 nanochips by subsequent thermal reduction, during which the Co(OH) 2 nanoflakes facilitate the formation of SmCo 5 nanochips as a template and Sm(OH) 3 nanorods help to maintain the hexagonal morphology and single crystal nature. The SmCo 5 nanochips exhibit strong magnetic anisotropy and excellent room temperature magnetic properties with a remanence of 7.7 kG, coercivity of 19.3 kOe, and maximum energy product of 14.4 MGOe, which is the highest recorded value for chemical synthesized nanostructured SmCo 5 particles. [ABSTRACT FROM AUTHOR]

In this study a new series of magnetic and heat resistant nanocomposites were prepared based on a highly soluble poly(imide-ether) (PIE) reinforced with two different types of magnetic nanoparticles via a solution intercalation technique. New PIE with good solubility and desired molar mass containing bulky xanthene rings and amide groups in the side chains was synthesized via thermal cyclization of the poly(amic acid) precursor, obtained from the reaction of a new diamine derived from 9H-xanthene and 4,4′-oxydiphthalic dianhydride (ODPA). Improved solubility was attributed to the presence of xanthene group and flexible ether linkage in the polyimide backbones that reduce the chain-chain interaction and enhance solubility by penetrating solvent molecules into the polyimide chains. Fe3O4 nanoparticles (MNPs) which synthesized from chemical co-precipitation route were coated with silica (SiO2), sequentially with (3-aminopropyl)triethoxysilane and poly-melamine-terephthaldehyde (MNPs-PMT), and then separately dispersed in the poly(amic acid) solutions and thermally imidized to form PIE/Fe3O4 and PIE/MNPs-PMT nanocomposites. The nanostructures and properties of the resultant materials were investigated using FTIR spectroscopy, X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), vibrating sample magnetometer (VSM), thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC). The properties of the nanocomposites were strongly related to the dispersion and interaction between the nanoparticles and PIE matrix. The thermogravimetric analysis (TGA) results showed that the addition of MNPs-PMT nanoparticles resulted in a substantial increase in the thermal stability of the corresponding PIEN. The temperature at 10% weight loss (T10) was increased from 416 °C to 428 °C for PIEN containing 3 wt% MNPs-PMT as compared to neat PIE, as well the char yield enhanced. Furthermore, the MNPs-PMT nanoparticles had better dispersion in the polymer matrix due to the strong intermolecular hydrogen bond interactions between the NH and C=N groups of surface-modified nanoparticles and the PIE matrix than the uncoated Fe3O4 nanoparticles, and exhibited a better intercalated morphology and improved thermal properties. Also, the PIEN nanocomposites under applied magnetic field exhibited the hysteretic loops of the superparamagnetic nature. [ABSTRACT FROM AUTHOR]

Abstract: A green synthesis of multifunctional superparamagnetic nanocomposites using the whole unripened fruit of Cassia fistula (Golden shower) with potential for removal of both cationic and anionic dyes and antimicrobial property is reported for the first time in the present work. A natural medium in the form of clarified butter was used to enhance the multifunctional character. The surface morphology, textural characteristics and composition of the prepared nanoparticles and composites were studied to understand the multifunctional nature. The dye removal was investigated for four different dyes, namely methyl blue, Congo red, rhodamine-B and auramine. Iron nanoparticles were largely effective in the removal of acidic dyes, while the magnetic nanocomposites were effective for the removal of both acidic and basic dyes which can be attributed to the functionalities imparted from Cassia fistula and clarified butter. The dye removal behavior can be significantly enhanced (~ 50%) using process intensification-adsorption coupled with acoustic cavitation, which also indicated a reduced adsorbent loading as compared to the conventional adsorptive dye removal. The nanomaterials were completely separated from dye solution with absolute ease of separation by applying simple magnetic field. Also, the developed materials were useful in disinfection of E. coli with a high efficiency of 90% confirming significant antimicrobial property at lower concentrations.Graphical Abstract: [ABSTRACT FROM AUTHOR]

Cobalt Molybdate (β-CoMoO 4 ) and Cobalt Oxide (Co 3 O 4 ) nanocomposite was prepared via co-precipitation and solid-state methods. Various techniques like powder XRD, FESEM, HRTEM, FTIR, VSM, UV–Vis and PL spectroscopy were used to investigate the structure and morphology of as prepared samples. Powder X-ray diffraction (XRD) reveals monoclinic and cubic structure for β-CoMoO 4 and Co 3 O 4 respectively. The surface morphology was observed using field emission electron microscopy (FESEM) and high-resolution transmission electron microscopy (HRTEM), which shows the formation of nanocomposites at nanoscale range, the presence of elements were determined by energy dispersive x-ray spectroscopy (EDX). FTIR analysis confirms the formation and bonding nature of the samples. The anti-ferromagnetic behavior of CMCO64 composite was determined by vibrating sample magnetometer (VSM). The bandgap values were calculated by extrapolating the straight line on the energy axis (hν), and the values of β-CoMoO 4, C O3 O 4 and β-CoMoO 4 - C O3 O 4 composites were determined to be 2.20, 2.09 eV and 1.54–2.44 eV respectively. The weak blue emission peak observed at 489 nm is corresponds to crystal defects only observed in CMCO01 and CMCO64 composite, for CMCO10 the peak shifted to green region. Antibacterial studies illustrate good result for the CMCO64 composite against both Gram-negative and Gram-positive bacteria. The sensor studies were measured at different humidity environment (RH 5% to RH 98% ). It was found that the increase in relative humidity leads to increase in the sensitivity factor of the samples. Among the samples CMCO64 composite possess highest sensitivity factor of (S f  = 4851) with response time of 60 s and recovery time of 230 s respectively. [ABSTRACT FROM AUTHOR]

We have studied structural, optical, electronic and magnetic properties of undoped well crystalline hexagonal and non-hexagonal ZnO system. X-ray diffraction (XRD) and high resolution transmission electron micrographs (HRTEM) of air annealed at 550 °C (sample-d) confirmed the presence of hexagonal (wurtzite) single phase ZnO. Raman analysis detected the vibrations of fundamental and second order phonons of Zn and oxygen related species. In Photoluminescence (PL) spectra, we observed that the intensity of UV peak decreases as annealing temperature increases. Broad PL visible band of samples shifted towards lower wavelength due to annealing effects. Fitting of broad PL spectra confirmed the existence of Zinc interstitial (Zn i ), Zinc vacancy (V Zn ) and oxygen vacancy (V o ) defects. To determine the Zn interstitial and vacancy defects Auger peaks were de-convoluted from X-ray photoelectron spectroscopy (XPS) survey scan. Oxygen vacancies are estimated by fitting of asymmetric XPS O-1s spectra. Incomplete oxidation of magnetization versus temperature in the presence of applied field showed the presence of irreversibility in 550 °C annealed-sample. Zn clusters and secondary phases are may be reason of room temperature ferromagnetism in non-hexagonal samples (a-c). While, complex defect (zinc and oxygen vacancies) as observed in electronic and PL data may be responsible for inducing, promoting and stabilizing room temperature ferromagnetism in well crystalline hexagonal ZnO nanoparticles (sample-d). [ABSTRACT FROM AUTHOR]

A novel magnetic nanocomposite (Lys-PGMA@Fe 3 O 4 ) containing amphoteric polymer brushes was synthesized by combining surface-initiated atom-transfer radical polymerization and lysine modification. The chemical structure of Lys-PGMA@Fe 3 O 4 was confirmed by multiple methods, such as FT-IR, TGA, elemental analysis. The core–brush morphology was clearly observed by transmission electron microscopy. Lys-PGMA@Fe 3 O 4 was then used to selectively and efficiently adsorb hazardous dyes. Adsorption results showed that Lys-PGMA@Fe 3 O 4 had considerable adsorption capacity (0.54 and 0.85 mmol·g −1 for LY and MEB, respectively) and rapid adsorption rate (within 10 min), which can be attributed to the nanosize and abundant adsorptive polymer brushes. The selective adsorption of a mixture of lemon yellow (pH = 4.0) and methylene blue (pH = 10.0) was achieved through the amphoteric polymer brushes. Similar to traditional adsorbent materials, Lys-PGMA@Fe 3 O 4 also showed easy magnet-assisted separation property. Lys-PGMA@Fe 3 O 4 adsorbent can also be regenerated to reduce application cost. Overall, results demonstrated that Lys-PGMA@Fe 3 O 4 nanocomposite was an excellent adsorbent material for removing dye pollutants from wastewater. [ABSTRACT FROM AUTHOR]

In this work, custom-made triple-tail sodium 1,4-bis(neopentyloxy)-3-(neopentyloxycarbonyl)-1,4-dioxobutane-2-silphonate (TC14) surfactant was used to assist exfoliation through electrochemical method for synthesis of graphene oxide (GO). A commercially available single-tail sodium dodecyl sulphate (SDS) surfactant was also utilised for comparison. Both synthesised GOs were reduced to produce reduced GO (rGO), which was fabricated into thin films through spray coating. The rGO thin film assisted by TC14 surfactant (TC14-rGO) with Pt nanoparticles was hybridised to improve electrical conductivity. The five different fabricated thin films were TC14-GO, TC14-rGO, SDS-rGO, Pt and TC14-rGO/Pt hybrid, which were used in dye-sensitised solar cells (DSSCs) as counter electrode (CE). Zinc oxide nanorods/titanium dioxide (ZnO NRs/TiO 2 bilayer) was used as photoanode and fabricated through a simple sol–gel immersion and squeegee method. Based on solar simulator measurement, TC14-rGO/Pt hybrid CE thin film exhibited the highest energy conversion efficiency of approximately 0.044% with the V oc , J sc and FF values of approximately 0.618 V, 0.163 mA/cm 2 and 0.387, respectively, compared with other fabricated CE materials. The combination of TC14-rGO/Pt hybrid CE and ZnO NRs/TiO 2 bilayer photoanode enhanced the DSSCs photovoltaic performance because of the high conductivity, low oxygen content, high quality and less agglomeration of thin rGO films as a result of improved exfoliation by triple-tail TC14 surfactant. [ABSTRACT FROM AUTHOR]

Magnetic graphene-based hybrids are being increasing recognized as an effective nanotheranostic agent in biomedicine. Conventional technologies for their synthesis have drawbacks not only from a synthetic standpoint, mainly requiring high temperatures and multi-step processes, but also from a biological perspective, chemical precursors or surfactants involved in the chemical process are toxic to cells. Herein, we report a novel approach for one-step fabricating magnetic graphene hybrid nanocomposites based on laser irradiation of an Fe target in GO-PEG aqueous solution at room temperature without using any other chemical reagent. TEM, XPS, FT-IR, XRD, Mossbauer spectrum and VSM observation reveal that γ-Fe 2 O 3 nanoparticles were directly grown on the surface of GO-PEG with uniform morphology and superior dispersibility. These GO-PEG-γ-Fe 2 O 3 nanocomposites (labeled as GPF) showed low cytotoxicity in vitro compared to chemically synthesized nanoparticles since the pulsed-laser-ablation-in-liquid (PLAL) process is free of toxic agents. After tail vein injection of the nanotheranostics, the tumor was clearly mapped by T 2 -weighted magnetic resonance of γ-Fe 2 O 3 , photothermal imaging of graphene and fluorescence imaging of loaded antitumor DOX. Meanwhile the tumor cells both in vitro and in vivo achieved highly superior inhibition by the synergistic chemo/photothermal therapeutic effect which provided an intense heating effect and enhanced DOX release upon 808 nm NIR light exposure. The results revealed that the magnetic graphene-based hybrids prepared by PLAL is competent for future multi-modal imaging assisted tumor targeted chemo/photothermal synergistic therapy of cancer. [ABSTRACT FROM AUTHOR]

While suitable texture has been developed in Nd2Fe14B/α-Fe nanocomposites via thermomechanical processing methods such as die upsetting by incorporating low melting point eutectic Nd-Cu additives, significant grain coarsening occurs during this process due to the high temperature and long timescales involved, resulting in a loss of exchange coupling. Equal channel angular pressing (ECAP) is a severe plastic deformation technique which has been successfully used to produce a suitable texture in single-phase Nd2Fe14B at temperatures on the order of 500°C while preserving grain sizes on the order of 20-30nm. We investigate the development of texture in a commercial Nd2Fe14B/α-Fe nanocomposite alloy with added Nd90Cu10 produced via ECAP and then characterise it using texture x-ray diffraction and magnetic measurements. It is found that initial texture can be developed in this nanocomposite system at T = 520°C via ECAP. The average grain size of Nd2Fe14B as measured via X-ray diffraction after ECAP remains below 50nm with a developed texture. The effect of varying the amount of Nd90Cu10 additive is also investigated. It is found that with decreasing Nd90Cu10, the degree of texture is reduced while the volume fraction of α-Fe increases. This work demonstrates the development of texture in nanocomposite Nd2Fe14B/α-Fe with Nd-Cu additives whilst maintaining a grain size of approximately 50nm. [ABSTRACT FROM AUTHOR]

Magnetic properties of nanocomposite materials containing particles of rare earth titanates of R 2 Ti 2 O 7 type, where R is a rare earth ion, including “spin ice” materials are investigated. The descending branches of hysteresis loop have been studied in detail in temperature range from 2 to 50 K. It has been shown that nanocomposites with Yb 2 Ti 2 O 7 , Dy 2 Ti 2 O 7 and Er 2 Ti 2 O 7 particles have one intersection point of the descending branches in some temperature range unlike many other nanocomposites. It is shown that magnetization has only weak temperature dependence near this point. It has been obtained that nanocomposites with Pr 2 Ti 2 O 7 and Nd 2 Ti 2 O 7 particles have no hysteresis loop. All above findings point out to unusual magnetic structures of the studied samples. [ABSTRACT FROM AUTHOR]

In this research new magnetic and semi crystalline poly(imide-ether)/zeolite nanocomposites were successfully fabricated via solution intercalation technique. For this purpose, novel functional diamine monomer, 4-(bis (4-(4-aminophenoxy)-2,5-dimethylphenyl) methyl)-N,N-dimethylbenzenamine (5), containing flexible ether, methyl and dimethylamino groups was successfully synthesized via three step reactions. The synthesized diamine (5), was used to prepare related soluble aromatic poly(imide-ether) (PIE) as a source of polymeric matrix by reaction with benzophenone-3,3′,4,4′-tetracarboxylic dianhydride. The synthesized PIE was assessed by Fourier transform infrared and nuclear magnetic resonance (1H-NMR) techniques. The synthesized PIE revealed good solubility in dipolar aprotic solvents at room temperature. The molecular geometry and electronic properties of PIE units in the ground state by DFT and B3LYP method with 6-31G (d) as basis set were studied. Due to incorporation of N,N-dimethyl amino group as an electron donor on the benzene ring in the structure of PIE, the highest occupied molecular orbitals (HOMO) are localized mainly on N,N-dimethyl aniline. The calculated energy values of HOMO and LUMO were − 5.48 and − 3.02 eV, respectively. Also, the HOMO-LUMO gap value of the studied PIE is − 2.06 eV which show PIE units having a small energy gap and are known as soft molecule. Nanozeolites ZSM-5 which synthesized from hydrothermal treatment was magnetized via chemical co-precipitation and used for preparation of new poly(imide-ether)/zeolite nanocomposites (PIEN 3% and PIEN 5%). The nanostructure and different properties of the nanocomposites were examined using transmission electron microscope, X-ray diffraction (XRD), ultraviolet-visible, gravimetric analysis (TGA), derivative of thermogravimetric, differential scanning calorimetry and vibrating sample magnetometer. The results of XRD studies illustrated that novel synthesized PIE and their nanocomposites exhibited a semi crystallinly pattern in X-ray diffraction analysis. The crystalline morphology of samples might be because of chain packaging of PIE and good intermolecular interaction of polymer chains due to presence of N,N-dimethylamine. In examining the optical properties, it has been observed that by increasing the concentration of the nanoparticle, PIEN 3% and PIEN 5% nanocomposites show decrease in wavelength and have a blue shift of 14 and 24 nm, respectively compared to pure PIE. Also, the PIEN nanocomposites under applied magnetic field exhibited the hysteretic loops of the superparamagnetic nature. Results of TGA measurement have shown that addition of MNZ-Fe3O4@ZSM-5 in PIE matrix increased the thermal stability, compared to the neat PIE. With increasing the content of MNZ-Fe3O4@ZSM-5 to 5 wt% due to agglomeration of nanoparticles T10% decreased slightly. The glass transition temperatures (Tg) of the PIE and their nanocomposites were about 240-255 °C. Briefly, the PIE and their nanocomposites showed high thermal stability while their solubility was improved. These properties will be useful for processing and new applications of poly(imide-ether). [ABSTRACT FROM AUTHOR]

Magnetic and ferroelectric properties in nanoscale are interesting topic to deal with. The primary interest is to understand the effect of simple, fast and cost effective sol gel method on the magnetic and electrical properties of Ba0.995Fe0.005Ti0.995Mn0.005O3 compounds. The study unravels the strategy for realizing multiferrocity of this composition by changing the processing temperature. Structural study confirms the infusion of Fe, Mn into the BaTiO3 lattice and its subsequent effects on the pseudo cubic and tetragonal phases. Morphological results manifest the formation of nanoparticles and evolution of grain growth upon increasing the processing temperature. Incorporation of Fe, Mn and its substantial effects on the various polymorphs of BaTiO3 is clearly portrayed by dielectric results. Room temperature ferroelectric measurements reveal the electric polarization in them. Magnetic measurements show an unusual high coercivity of 4000 Oe and its transformation to a completely paramagnetic behaviour with the subsequent changes in their phase. Thus, the pseudo cubic phase aids to retain the ferroelectric polarization with simultaneous presence of magnetic signature hints their possibility towards fruitful multi-functionality. [ABSTRACT FROM AUTHOR]

In this work, hybrid nanocomposites of reduced graphene oxide/multi-walled carbon nanotubes/zinc ferrite (RGO/MWCNTs/ZnFe 2 O 4 ) were fabricated by a facile one-pot hydrothermal strategy. Effect of the mass ratio of GO to MWCNTs on the structure, morphology, magnetic properties and microwave absorption properties of the as-prepared hybrid nanocomposites was investigated in detail. Results demonstrated that the surface of MWCNTs were loaded with ZnFe 2 O 4 nanoparticles and interlinked with RGO, which constructed the three-dimensional (3D) conductive networks in the ternary nanocomposites. Moreover, the ternary nanocomposites exhibited enhanced microwave absorption with the minimum reflection loss of −23.8 dB and effective absorption bandwidth (less than −10 dB) of 2.6 GHz. Significantly, the dual-waveband absorption characteristics covering the C and Ku bands were observed. Therefore, the obtained hybrid nanocomposites were potential candidates for application in the field of microwave absorption. [ABSTRACT FROM AUTHOR]

In this study, spinel magnesium cobalt ferrite (Co x Mg 1−x Fe 2 O 4 : x  = 0.0, 0.2, 0.4, 0.6, 0.8 and 1.0) nanocomposites were synthesized successfully by modified sol-gel combustion method. Magnesium nitrate, cobalt nitrate and iron nitrate were used as the source of divalent (Mg 2+ and Co 2+ ) and trivalent (Fe 3+ ) cations, respectively and urea were used as the reducing (fuel) agent. The effects of cobalt ions on morphology, structural, optical, magnetic and photo-catalytic properties of spinel Co x Mg 1−x Fe 2 O 4 nanocomposites were investigated. Various characterization methods, including X-ray powder diffraction (XRD), high resolution scanning electron microscope (HR-SEM), transmission electron microscopy (HR-TEM), energy-dispersive X-ray spectroscopy (EDX), Fourier transforms infrared (FT-IR) spectroscopy, vibrating sample magnetometer (VSM) and photo-catalytic degradation (PCD) activity were used to study the phase purity, microstructure, particle size, elemental composition, functional group determination, band gap calculation, magnetic properties and degradation efficiency of nanoparticles, respectively. The observed results showed that the final products consists cubic spinel phase with sphere-like nanoparticles morphologies. Furthermore, spinel Co 0.6 Mg 0.4 Fe 2 O 4 nanocomposite showed highest PCD efficiency (98.55%) than other composition of ferrite nanoparticles. [ABSTRACT FROM AUTHOR]

CeO 2 , NiO and their nanocomposite were synthesized using facile sonochemical technique. XRD assure single phase CeO 2 and NiO while the nanocomposite consists of the two phases only. CeO 2 nanoparticles possess cubic shape, NiO was formed in nanorods, and CeO 2 decorated the NiO nanorods in the nanocomposite. The magnetic behavior of the nanocomposite lies between those of the two parents with a ferromagnetic tendency. Metal oxide nanoparticles acted as catalyst in the formation of carbon nanofibers (CNFs), while the nanocomposite leads to the production of carbon nanotubes. The photocatalyst (CeO 2 -NiO) achieved complete dye degradation (100%) in light for the tested dye at 50 min. The decay products were analyzed using GC mass confirming mineralization of Bb red dye. [ABSTRACT FROM AUTHOR]

A novel super acidic magnetic nanoparticle as catalyst was successfully synthesized. The preparation of this dendrimer sulfonic acid functionalized γ‐Fe2O3 magnetic core‐shell silica nanoparticles as a new recoverable and heterogeneous nanocatalyst was described. The new catalyst was characterized using various techniques such as scanning electron microscopy (SEM), energy dispersive spectrum (EDS), and thermo gravimetric synthesis (TGA). Moreover, we have examined the catalytic activity of the catalyst for one‐pot, efficient and facile synthesis of 2‐hydroxy‐1,4‐naphthoquinone derivatives via a three‐component condensation reaction of 2‐hydroxynaphthalene‐1,4‐dione, aromatic aldehydes and aniline derivatives. High yields of products, short reaction times, waste‐free, mild, ambient and solvent‐free reaction conditions are advantages of this protocol. Also, the catalyst can be easily recovered by an external magnetic and reused several times without significant loss of its catalytic activity. [ABSTRACT FROM AUTHOR]

Our studies on the crystal characterization and magnetic property of CoFe 2 O 4 nanoparticles (NPs) point out their instability in a specific temperature range. While as-prepared NPs exhibit single phase in a cubic spinel structure, annealing at temperatures T =673–1273 K leads to the development of an impurity phase of Fe 2 O 3 . Interestingly, annealing at higher temperatures re-creates the single phase of NPs. This strongly influences their magnetic property. The magnetic inhomogeneity and/or multiple phase exist in as-prepared NPs and in those annealed below 1273 K, better magnetic property is found in the samples with annealing temperature ( T an ) higher than 1273 K. Ferromagnetic-paramagnetic phase transition temperatures of these samples are located around 815–850 K, and are less dependent on T an . At room temperature, their saturation magnetization is located in the range of 41–55 emu/g, while the coercivity can be changed from 600 to ~3200 Oe. These results are related to microstructures, structural phases, and exchange interactions between Fe and Co ions situated in the A and B sites of the spinel structure, which are modified by heat treatment. [ABSTRACT FROM AUTHOR]

The effect of variation in composition on the structural, magnetic, optical and photo catalytic activity of magnesium ferrite (MgFe 2 O 4 ) -graphene oxide (GO) nanocomposites was studied. Magnetic nanocomposites of GO and MgFe 2 O 4 nanoparticles (NPs) with varying w/w ratio were synthesized by facile sonication method. X-Ray diffraction patterns confirmed the presence of spinel ferrite phase in the nanocomposites with the crystalline size 8–32 nm. Fourier transformation infrared (FT-IR) spectra of the nanocomposites displayed absorption bands corresponding to GO and MgFe 2 O 4 NPs along with red shift of bands corresponding to C=O, C=C and O-H stretching. Thermo gravimetric analysis confirmed higher stability of nanocomposites over pristine GO. Saturation magnetization increased from 3.63 to 11.10 emu/g with the increase in content of MgFe 2 O 4 NPs in the nanocomposites. Scanning electron microscopy analysis along with energy dispersive spectroscopy (SEM-EDX) confirmed the presence of MgFe 2 O 4 NPs along with GO sheets. Immobilization of clusters of MgFe 2 O 4 NPs onto GO sheets was evident from transmission electron micrographs (TEM) of all the nanocomposites. BET surface area of the nanocomposites ranged from 63.04 to 165.29 m 2 /g and was maximum when GO:MgFe 2 O 4 w/w ratio was 1:0.5. It was markedly higher than pristine GO and MgFe 2 O 4 NPs. Optical studies revealed lowering of the band gap in the nanocomposites upto 2.21 eV as compared to pristine MgFe 2 O 4 NPs. Photoluminescence (PL) spectra of nanocomposites displayed quenching of PL intensity with increase of GO content. Band gap also displayed similar trend. The synthesized nanocomposites were used as photocatalysts for methylene blue dye degradation under visible light irradiation. The nanocomposite with GO to MgFe 2 O 4 ratio 1:0.5 displayed best activity with complete degradation of dye in 30 min. The results confirmed that the composition of GO based magnetic nanocomposites can be tailored for efficient removal of contaminants. [ABSTRACT FROM AUTHOR]

The properties of (CoFeB)x(LiNbOy)100-x nanocomposite films with a ferromagnetic alloy content x = 6-48 at % are comprehensively studied. The films are shown to consist of ensembles of CoFe granules 2-4 nm in size, which are strongly elongated (up to 10-15 nm) in the nanocomposite growth direction and are located in an LiNbOy matrix with a high content of Fe2+ and Co2+ magnetic ions (up to 3 × 1022 cm-3). At T ≤ 25 K, a paramagnetic component of the magnetization of nanocomposites is detected along with a ferromagnetic component, and the contribution of the former component is threefold that of the latter. A hysteresis of the magnetization is observed below the percolation threshold up to x ≈ 33 at %, which indicates the appearance of a superferromagnetic order in the nanocomposites. The temperature dependence of the electrical conductivity of the nanocomposites in the range T ≈ 10-200 K on the metallic side of the metal-insulator transition (44 at % < x < 48 at %) is described by a logarithmic law σ(T) ∝ lnT. This law changes into the law of “1/2” at x ≤ 40 at %. The tunneling anomalous Hall effect is strongly suppressed and the longitudinal conductivity turns out to be lower than in a (CoFeB)x(AlOy)100-x composite material by an order of magnitude. The capacitor structures based on (CoFeB)x(LiNbOy)100-x films exhibit resistive switching effects. They are related to (i) the formation of isolated chains of elongated granules and an anomalously strong decrease in the resistance in fields E > 104 V/cm because of the suppression of Coulomb blockage effects and the generation of oxygen vacancies VO and (ii) the injection (or extraction) of VO vacancies (depending on the sign of voltage) into a strongly oxidized layer in the nanocomposites, which is located near an electrode of the structure and controls its resistance. The number of stable resistive switchings exceeds 105 at a resistance ratio Roff/Ron ~ 50. [ABSTRACT FROM AUTHOR]

Graphene-based adsorbents have attracted wide interests as effective adsorbents for heavy metals removal from the environment. Due to their excellent electrical, mechanical, optical and transport properties, graphene and its derivatives such as graphene oxide (GO) have found various applications. However, in many applications, surface modification is necessary as pristine graphene/GO may be ineffective in some specific applications such as adsorption of heavy metal ions. Consequently, the modification of graphene/GO using various metals and non-metals is an ongoing research effort in the carbon-material realm. The use of organic materials represents an economical and environmentally friendly approach in modifying GO for environmental applications such as heavy metal adsorption. This review discusses the applications of organo-functionalized GO composites for the adsorption of heavy metals. The aspects reviewed include the commonly used organic materials for modifying GO, the performance of the modified composites in heavy metals adsorption, effects of operational parameters, adsorption mechanisms and kinetic, as well as the stability of the adsorbents. Despite the significant research efforts on GO modification, many aspects such as the interaction between the functional groups and the heavy metal ions, and the quantitative effect of the functional groups are yet to be fully understood. The review, therefore, offers some perspectives on the future research needs. [ABSTRACT FROM AUTHOR]

In the present work, we have investigated structural, dielectric, ac conductivity, magnetic and electromagnetic interference (EMI) shielding effectiveness (SE) performance of Co0.5Ni0.5Fe2O4 nanoparticles and Polyaniline (PANI)/Co0.5Ni0.5Fe2O4 nanocomposites for EMI shielding applications. The Co0.5Ni0.5Fe2O4 nanoparticles were synthesized by solution combustion method. PANI/Co0.5Ni0.5Fe2O4 nanocomposites were prepared by in-situ polymerization method. As-prepared samples were examined by using X-ray diffraction (XRD) and Fourier transform infrared (FT-IR) spectroscopy. The microstructural and composition studies have been performed using Field emission scanning electron microscopy (FE-SEM) and Energy Dispersive X-ray (EDX) analysis. Thermal stability of the composite was analyzed using thermo gravimetric analysis (TGA). Frequency dependence of dielectric and ac conductivity (σac) studies have been undertaken on the Co0.5Ni0.5Fe2O4 nanoparticles and PANI/Co0.5Ni0.5Fe2O4 nanocomposites in the frequency range 50 Hz–5 MHz. The electrical conduction mechanism in the synthesized samples found to be in accordance with the electron hopping model. Present Co0.5Ni0.5Fe2O4 nanoparticles and PANI/Co0.5Ni0.5Fe2O4 nanocomposites exhibited hysteretic behavior under the applied magnetic field at room temperature. The maximum values 39.9 and 58.22 dB of SE at 50 Hz were obtained at room temperature for Co0.5Ni0.5Fe2O4 nanoparticles and PANI/Co0.5Ni0.5Fe2O4 nanocomposites respectively. Present Co0.5Ni0.5Fe2O4 nanoparticles decorated with PANI can be recognized as a promising functional material for the absorbing of electromagnetic (EM) waves due to large amount of dipole polarizations in the polymer backbone and at the interfaces of the Co–Ni ferrite nanoparticles and PANI matrix. [ABSTRACT FROM AUTHOR]

Poly(o-phenylenediamine) ferrite nanocomposites (PoPD/NiFe2O4) with different ratios of NiFe2O4 nanoparticles (10%, 20% and 30%) were synthesized by in-situ chemical oxidative polymerization method. NiFe2O4 nanoparticles were prepared by auto-combustion method using urea as fuel. The PoPD/NiFe2O4 nanocomposites were characterized by FTIR and XRD, SEM, TEM and thermogravimetric analysis. The FTIR and XRD pattern ascertain the interaction of PoPD with NiFe2O4 nanoparticles. The spherical morphology of PoPD is affected by the incorporation of NiFe2O4 nanoparticles. Magnetic properties of PoPD/NiFe2O4 nanocomposites were analyzed by using vibrating sample magnetometer. The hysteresis loops of NiFe2O4 and PoPD/NiFe2O4 nanocomposites exhibited ferromagnetic nature at room temperature. Dielectric properties of PoPD/NiFe2O4 nanocomposites at different temperatures have been carried in the frequency range from 50 Hz to 5 MHz. The ethanol gas sensing property of PoPD/NiFe2O4 nanocomposites was studied at room temperature using PMMA fiber optic method. [ABSTRACT FROM AUTHOR]

The magnetic/metallic nanocomposites are special intelligent materials and find many applications in photonics, magneto-optical devices, and biosensors. This paper introduces the synthesis and performance of FeO/Ag ferrofluids using a facile one-step modified co-precipitation method. The nanocomposites were characterized using X-ray diffraction, scanning electron microscopy, XPS, and Fourier transform infrared spectra for structure, morphology, and component investigation, respectively. The viscosity, stability, magnetic, and magneto-optical properties of the ferrofluids were measured through the vibrating sample magnetometer, Faraday rotation optical bench, and viscosity tester. FeO/Ag-based ferrofluids demonstrated good stability (did not agglomerate for 120 h), big magnetic field-dependent-viscosity, surface plasmon resonance effect, superpagamagnetic nature, and improved Faraday effect; these characters are good for MO sensing application. The Verdet constant of ferrofluids at 633 nm increased from 5.66 to 8.53 × 10 deg/G cm after Ag coating on FeO. [ABSTRACT FROM AUTHOR]

Al 2 O 3 , Al 2 O 3 -1 wt% Carbon Nanotube (CNT) and Al 2 O 3 -1 wt% CNT-0.5 wt% Graphene Nanoplatelets (GNP) were consolidated by spark plasma sintering at a temperature of 1500 °C. Spray drying technique was used for uniformly distributing the CNTs and GNPs. Fracture toughness of Al 2 O 3 pellet drastically increased to 168% on addition of CNTs, while substantial improvement of 250% was seen on the addition of both CNTs and GNPs. Interfacial shear stress for Al 2 O 3 -CNT-GNP was found to be 350–1100 MPa. Novel toughening mechanisms such as CNT yarning and CNT embedded graphene was found responsible for the drastic improvement in toughness. [ABSTRACT FROM AUTHOR]

In this work, tin ferrite nanoparticles were first synthesized by simple chemical procedures such as co precipitation, sol-gel auto combustion and hydrothermal methods. In general, all three methods were compared in the synthesis of nanoparticles. Then tin ferrite-tin oxide (50%:50%) nanocomposites were prepared using co precipitation method. Crystal structures of nanoparticles and nanocomposite were studied using X-ray diffraction pattern. The particle size was determined by Scanning Electron Microscopy. Vibrating sample magnetometer was used to study the magnetic property of the products. And also, by applying Fourier transform infrared spectrometer, the purity of the material was determined. Photocatalytic activity of nanoparticles and nanocomposites was investigated under ultra-violet and visible spectroscopy (UV-Vis). The results show that prepared nanocomposites are applicable for magnetic and photocatalytic performance and they were able to degrade azo dyes (organic dyes) under UV-Vis radiation. [ABSTRACT FROM AUTHOR]

We herein report in-situ solvothermal method to prepare Fe 3 O 4 nanoparticles-coated porous BN microrods (p-BNMR@Fe 3 O 4 ) nanocomposites. A combination of the XRD, SEM and TEM characterization indicates that the good-crystallinity Fe 3 O 4 nanoparticles with an average size of 7 nm are uniformly coated on the surface of p-BNMRs. The as-prepared p-BNMR@Fe 3 O 4 nanocomposites perform significant adsorption activity for Pb(II), and the maximum adsorption capacity is as high as 249.5 mg/g when the initial concentration of Pb(II) is 180 mg/L at room temperature with pH of 5.5. In addition, the superparamagnetic property of the p-BNMR@Fe 3 O 4 nanocomposites also enabled the rapid separation by a low magnetic field. Consequently, the p-BNMR@Fe 3 O 4 nanocomposites have great potential in treating Pb(II)-contaminated water. [ABSTRACT FROM AUTHOR]

Novel magnetically recyclable MoS@FeO nanocomposite with remarkable photocatalytic capability was prepared by virtue of a rational hydrothermal route. The as-synthesized nanocomposites were well characterized by various spectroscopic and microscopic techniques, including X-ray powder diffraction, field-emission scanning electron microscope, transmission electron microscopy, energy-dispersive spectrometer, X-ray photoelectron spectroscopy, N adsorption-desorption isotherm (BET), ultraviolet-visible diffuse reflectance spectroscopy, fluorescence spectrophotometer and vibrating sample magnetometer, showing good structural, compositional, optical and magnetic properties. Photocatalytic activity was evaluated by degrading rhodamine B (RhB) and methylene blue (MB) aqueous solution under visible-light irradiation. In comparison with pure MoS, the MoS@FeO with 17 wt% dosage of FeO (MF-17) possessed superior photocatalytic performance. The photocatalytic degradation showed an evident dependence on the initial pH value with respect to the RhB and MB solutions, where the optimal degradation efficiency was obtained at pH 3.0 and 11.0, respectively. More importantly, magnetic MoS@FeO hybrid can be well separated and easily recycled by an external magnetic field, still maintaining advanced activity after eight photoreaction cycles. [ABSTRACT FROM AUTHOR]

Magnetic nanocomposites of CoFe 2 -CoFe 2 O 4 were synthesized using the borohydride reduction process in a chitosan solution of FeCl 2 ·4H 2 O and CoCl 2 ·6H 2 O. The chemical crosslinking favored the formation of cobalt ferrite in the nanoparticle synthesis process. The phase structure, particle size, morphology and magnetization of the nanoparticles were investigated by X-ray diffraction (XRD), Mössbauer spectroscopy (MS), scanning electron microscopy, and vibrating sample magnetoscopy, respectively. The XRD results showed that the samples are mostly made up of amorphous phases and MS shows that the phases are Fe-B. The average size of the nanoparticles obtained varied within a range of 4–13 nm. Different magnetic behavior such as ferromagnetism, spin glass and exchange-spring were observed in the nanocomposites depending on the quantify of CoFe 2 O 4 . [ABSTRACT FROM AUTHOR]

Polyvinyl alcohol (PVA) composite magnetite nanoparticles were synthesized by co-precipitation method. The crystalline, structural, thermal and magnetic properties of PVA composite magnetite nanoparticles were characterized using XRD, TEM, FTIR, TGA and VSM analytical techniques. The average particle size of prepared pure magnetite and PVA-magnetite nanocomposite were determined through XRD technique and found to be below 20 and 17 nm respectively which was further confirmed in TEM imaging. The functional compositions and formation of PVA-magnetite composite were confirmed by FTIR analysis. Thermal properties and extent of PVA in the composite nanoparticles were evaluated using thermo-gravimetric analysis (TGA). VSM studies have shown that magnetite and PVA-magnetite composite nanoparticles exhibit super paramagnetic behavior at room temperature with saturation magnetization value of 60.21 emu/g, 47.22 emu/g respectively. [ABSTRACT FROM AUTHOR]