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Shape-controlled synthesis of zinc ferrite (ZnFe2O4) nanospheres has been accomplished via a facile one-step solvothermal method. As a structure-directing agent, sodium acetate (NaAc) has been utilized in this method with different concentrations. Compared to bulk ZnFe2O4 with a normal spinel structure, the lattice parameter of the synthesized ZnFe2O4 samples estimated by x-ray diffraction was lower. The reduction in the lattice parameters of synthesized samples indicate the possibility of ZnFe2O4 developing in a mixed spinel structure. Morphological studies indicate that low amounts of NaAc shape the agglomerated spherical structure of ZnFe2O4 during synthesis. However, the inclusion of a large amount of NaAc results in nanospheres of ZnFe2O4 without any agglomeration. The electro-stabilizing property of the NaAc and Ostwald ripening process plays a leading role in shaping the nanostructures during the synthesis. The magnetic properties produce super-paramagnetic behavior in all ZnFe2O4 samples. The highest saturation magnetization of 23.08 emu/g was recorded in the sample synthesized using the lowest concentration of NaAc, and has been attributed to cationic inversion due to the small particle size. Despite having comparable nanograin sizes, the agglomerated spherical ZnFe2O4 nanostructures showed a larger saturation magnetization than the deagglomerated ones in the absence of coupled exchange interactions between the nanograins in the latter. [ABSTRACT FROM AUTHOR]

• Particle size is different after lower sintering temperatures while it becomes same after 1100°c of sintering in both the nanoparticles of CoFe 2 O 4 and CoAlFeO 4. • Saturation magnetization increases consistently as sintering temperature increases 300 to 1100 °C. • Remanent magnetization decreases in CoFe 2 O 4 while increases in CoAlFeO 4. • Superparamagnetic and ferrimagnetic nature coexist simultaneous in CoAlFeO 4 nanoparticles. • Cationic distribution strictly depends on heat treatment of the samples. In the present work a systematic study has been carried out for the CoFe 2 O 4 and CoAlFeO 4 nanoparticles by means of x-ray diffraction, Transmission electron microscopy (TEM), Vibrating sample magnetometer (VSM) and Mössbauer spectroscopic techniques. Sol gel auto combustion method was employed to synthesize the studied compounds. From x-ray diffraction data followed by the simulation via Rietveld refinement, cationic distribution between tetrahedral and octahedral sites has been determined. A significant reduction in the lattice parameter (∼0.1 Å) and crystallite size (∼20 nm) has been observed after the Al doping in the CoFe 2 O 4 nanoparticles and at 1100 °C of sintering the particle size of doped and undoped samples become same ∼45 nm. The obtained results from TEM measurements are complement to the x-ray diffraction results. Magnetic measurements reveal the correlation of magnetic properties with the sintering temperature. In CoFe 2 O 4 nanoparticles 60 % decrement in coercivity and 44 % decrement in remanent magnetization was observed as the sintering temperature increases from 300 to 1100 °C. While in CoAlFeO 4 samples 85 % reduction in coercivity and 74 % increment in remanent magnetization was observed with same sintering temperatures. Mössbauer spectra confirmed the coexistence of superparamagnetic and ferrimagnetic behavior in the CoAlFeO 4 nanoparticles at room temperature, which was absent in the CoFe 2 O 4 nanoparticles. Furthermore, the obtained cationic distribution from the Mössbauer spectra is in consistent with the Rietveld refined data. The decrease in the internal magnetic field is explained in terms of the weakening of the A-B exchange interaction. [ABSTRACT FROM AUTHOR]

Inspired by the multi-functionalities of vegetal extracts, we first focused on developing a new gold nanoparticle (AuNP) synthesis method using tomato extract (Solanum lycopersicum Mill, Carmen variety) under conditions in which proteins could be preserved and unexpected additional synthesis of superparamagnetic magnetite occurred. The AuNPs and magnetite were characterized by UV–visible spectroscopy, dynamic light scattering, superconducting quantum interference device, high-resolution transmission microscopy and energy-dispersive X-ray spectroscopy. Based on the literature, the ferrihydrite core of holoferritin was postulated to be the magnetite precursor. Consistently, the tomato genome encodes a protein homologous to ferritin and an identical result was obtained with purified horse spleen ferritin (HSF). The electron paramagnetic resonance spectrum of the lyophilized tomato pulp extract at 298 K featured HSF signal with (g0 = 2.070). This signal is absent in another tomato variety (Solanum lycopersicum, cherry variety), as well as in the boiled Carmen tomato extract, which produced only AuNPs after stirring with HAuCl4. The synthesis of magnetite in an air atmosphere is feasible only using holoferritin because the synthesis by loading apoferritin with iron salt requires an inert atmosphere and controlled stoichiometry. In addition, AuNPs produced by this method exhibited potential for use in photodynamic therapy. [ABSTRACT FROM AUTHOR]

The magnetic and electrical properties of two different sets of carbon nanospheres synthesised by chemical vapour deposition were investigated, using a state-of-the-art Physical Property Measurement System (PPMS). Scanning electron microscopy imaging of the carbon nanospheres revealed a difference in size with a diameters distribution of approximately 200–400 nm and 400–500 nm. PPMS magnetic measurements of the 400–500 nm diameter carbon nanospheres exhibited diamagnetism at high temperatures and clear superparamagnetic behaviour at very low temperatures (< 10 K). However, ferromagnetism was observed in carbon nanospheres of diameter < 400 nm. The results obtained from both inductively Coupled Plasma Mass Spectrometry and Mössbauer spectroscopy, and as well as the calculated saturation magnetisation indicate that the observed ferromagnetism in the carbon nanospheres of diameter < 400 nm is intrinsic and could not be accounted for by the magnetic impurities such as Fe and Ni introduced during the synthesis process. The electrical properties of a network of carbon nanospheres were investigated and showed a variable range hopping class of conductivity. [Display omitted] • Carbon nanospheres synthesised by chemical vapour deposition for 20 min exhibits ferromagnetic behaviour. • The ferromagnetism is intrinsic and cannot be accounted for by magnetic impurities. • Super-paramagnetic characteristic is depicted at 2 K in carbon nanospheres synthesised for 40 min. • The electrical resistance shows a variable range hopping class of conduction at low temperatures and thermal activation conduction at high temperatures. [ABSTRACT FROM AUTHOR]

Abstract Nano-sized superconducting polycrystalline particles of Mg 1-x Fe x B 2 (0.00 ≤ x ≤ 0.04; space group P6/ mmm) were synthesized through the solid state reaction route. The effect of nano-Fe substitution on ac -susceptibility at varying frequency range from 1 to 3 kHz in addition with ac -amplitude (H ac) and dc -applied field (H dc) were explored. The dynamical behavior of nano-particles shows the strong magnetic interaction between the nano-clusters with the increase of doping content. This is due to the successful inclusion of Fe3+ ions in the matrix of MgB 2. X-ray powder diffraction (XRD) reveals the reduction of average grain size with increasing the doping level. Neel-Arrhenius (N-A) and Vogel-Fulcher (V-F) models were discussed to distinguish the dynamical behaviors of the nano-particles. Remarkably, the V-F model elucidates the experimental results much better than N-A model with the support of some parameters like jump attempt frequency, activation energy, magnetic anisotropy constant and V-F temperature. [ABSTRACT FROM AUTHOR]

Attarad Ali,1 Hira Zafar,1 Muhammad Zia,1 Ihsan ul Haq,2 Abdul Rehman Phull,3 Joham Sarfraz Ali,1 Altaf Hussain4 1Department of Biotechnology, 2Department of Pharmacy, Quaid-i-Azam University, Islamabad, Pakistan; 3Department of Biology, Kongju National University, Kongju, South Korea; 4Department of Materials Science and Engineering, Institute of Space Technology, Islamabad, Pakistan Abstract: Recently, iron oxide nanoparticles (NPs) have attracted much consideration due to their unique properties, such as superparamagnetism, surface-to-volume ratio, greater surface area, and easy separation methodology. Various physical, chemical, and biological methods have been adopted to synthesize magnetic NPs with suitable surface chemistry. This review summarizes the methods for the preparation of iron oxide NPs, size and morphology control, and magnetic properties with recent bioengineering, commercial, and industrial applications. Iron oxides exhibit great potential in the fields of life sciences such as biomedicine, agriculture, and environment. Nontoxic conduct and biocompatible applications of magnetic NPs can be enriched further by special surface coating with organic or inorganic molecules, including surfactants, drugs, proteins, starches, enzymes, antibodies, nucleotides, nonionic detergents, and polyelectrolytes. Magnetic NPs can also be directed to an organ, tissue, or tumor using an external magnetic field for hyperthermic treatment of patients. Keeping in mind the current interest in iron NPs, this review is designed to report recent information from synthesis to characterization, and applications of iron NPs. Keywords: superparamagnetism, iron oxide nanoparticles, surfactants, hyperthermia, biodistribution, bioelimination

Ce 1-x In x O 2 (x = 0.0, 0.02, 0.04, 0.06, 0.10 and 0.15) nanoparticles have been successfully synthesized by sol gel method using citric acid as a gelling agent. The gel obtained was characterised using DG-DTA analysis. The XRD confirmed the fluorite phase formation and purity of the compounds. Morphological studies revealed the flaky and porous nature as seen from SEM images. TEM showed that the average particle size obtained is less than 20 nm. The existence of Ce 3+ /Ce +4 oxidation states is confirmed from XPS data which in turn results in the oxygen deficiency in the system. The Electrical studies displayed the typical semiconductor nature of the nano-particles. The dilute magnetic property has been studied using VSM where the existence of very weak room temperature ferromagnetism is seen in pristine sample which is found to be enhanced on indium doping where for Ce 0.85 In 0.15 O 2 composition showed a super-paramagnetic nature with negligible coercivity (H c ) , in magnetisation v/s field studies. The saturation magnetisation ( M s ) and coercivity (H c ) are further found to be enhanced at 50 K. When compared with the bulk sample the magnetism here was found to be lowered or reduced. This suggests that the oxygen vacancies and defects in the nanostructure are responsible for the observed magnetic behaviour in the prepared compounds. [ABSTRACT FROM AUTHOR]

Magnesium-doped Zinc ferrite (Mg x Zn 1-x Fe 2 O 4) nanoparticles with an average size of 10.1-5.89 nm were prepared by low-temperature hydrothermal method using NaBH 4 as the reducing agent. The structural, microstructural, optical, magnetic, and dielectric properties of these nanoparticles were extensively studied. Rietveld refinement profile confirmed the formation of mixed spinel structures with cubic lattices (space group Fd3m). A complete microstructural study revealed the polycrystallinity nature of the powder along with the formation of nano-sized particles. The Raman spectral analysis showed broadening, merging, and shifting of Raman peaks with an increase in dopant concentration. The X-ray photoelectron studies exhibited the presence of Fe2+ and Fe3+ ions corroborating the results obtained from Rietveld analysis. The optical studies elucidate a reasonably high absorbance in the UV region with a bandgap of 2.05-1.92 eV, which showed a minimum value of 1.92 eV for 50% of Mg doping. These nano-sized ferrite particles were observed to be superparamagnetic due to their small size and gradually developed to a ferromagnetic state, but with a low value of magnetization, coercivity, and remanent magnetization. These nano ferrites exhibiting high dielectric constant, high impedance, and significantly low loss may have potential applications in communication devices. • Synthesis of mixed spinel Mg x Zn 1-x Fe 2 O 4 (x = 0–0.5) nanoparticles by hydrothermal method using NaBH 4. • Single-domain superparamagnetic nature of nano ferrites was observed through magnetic study due to their small size. • Exhibiting high dielectric constant, high impedance and low loss may have potential application in communication devices. [ABSTRACT FROM AUTHOR]

In this work, super-paramagnetic nano-architecture was designed to remove the organic pollutants effectively from the waste water. The nano-architectures are composed of super-paramagnetic Fe 3 O 4 hollow spheres, conductive polymer and graphene sheets (RGO) to form binary and ternary nano-architectures. They could be magnetically separated and well-distributed into wastewater again for recycle use. Due to the special function of PPy shell, the binary Fe 3 O 4 @PPy core-shell structure exhibits pH-responsive removal efficiency for organic pollutants. Assembling the Fe 3 O 4 @PPy core-shell material with RGO sheets could largely improve their surface area, pore volume, and enhance their chemical stability in acid and alkaline solution. Therefore, the Fe 3 O 4 @PPy@RGO ternary nano-adsorbents could show favorable and robust removal performance for organic pollutants no matter in neutral, acidic and alkaline environment. [ABSTRACT FROM AUTHOR]

High density, soot free, novel and a facile approach toward synthesis of carbon nanoropes (CNRs) were successfully carried out in a chemical vapor deposition (CVD) process. Manganese ferrite (MnFe 2 O 4 ) coated on stainless steel foil (SS 316 grade) was used as a catalyst to initiate the growth of CNR. The coated catalyst was introduced into the CVD and the chamber temperature was set at 700 °C later followed with the release of acetylene (50 sccm) and nitrogen (500 sccm) gas, respectively. Total reaction continued until 30 min. No purification or oxidation process of the soot was involved. Analysis reveals the presence of intermingled CNRs with semi crystalline nature of the sample. The elemental analysis confirms the presence of manganese and iron whereas Raman spectrum shows the characteristic narrow G and D bands. The sample displays a super-paramagnetic behavior and is thermally stable up to 500–550 °C presenting a strong exothermic reaction. [ABSTRACT FROM AUTHOR]

High intensity ultrasound was used for the synthesis and simultaneous deposition of TiO 2 :Fe 3 O 4 :Ag nanocomposites on polyester surface providing a feasible route for imparting magnetic and enhanced antibacterial and self-cleaning activities with controllable hydrophilicity/hydrophobicity at low temperature. Synergistic impact of sonochemistry and physical effects of ultrasound originating from implosive collapse of bubbles were responsible for the formation and adsorption of nanomaterials on the fabric surface during ultrasound irradiation. The increase in photocatalytic activity of TiO 2 was obtained attributing to the co-operation of iron oxide and silver nanoparticles nucleated on TiO 2 surface boosting the electron–hole pair separation and prolonging their recombination rate. The process was further optimized in terms of reagents concentrations including Fe 2+ /TiO 2 and Ag/TiO 2 molar ratios using central composite design in order to achieve the best self-cleaning property of the treated fabric. The magnetic measurements indicated the super-paramagnetic behavior of the treated fabric with saturation magnetization of 4.5 (emu/g). Findings suggest the potential of the proposed facial method in producing an intelligent fabric with durable multi-functional activities that can be suitable for various applications including medical, military, bio-separation, bio-sensors, magneto graphic printing, magnetic screens and magnetic filters. [ABSTRACT FROM AUTHOR]

An innovative TiO2/iron oxide/Ag nanoparticle, with crystal size of about 25 nm, was synthesized on polyester fabric to achieve different multi-features, including super-paramagnetism, antibacterial and enhanced self-cleaning properties. Treatment temperature was varied at boiling and 130°C, creating TiO2/magnetite/silver and TiO2/hematite/silver nanoparticles, respectively. The alkaline hydrolysis of the polyester surface was accompanied by nanoparticle synthesis, which forms a more active surface for nanoparticle adsorption. The co-operation of iron oxide and silver nanoparticles on the TiO2 surface synergistically improved the self-cleaning efficiency of titanium dioxide nanoparticles by separation of electron-hole pairs, three and four times, for fabrics treated with TiO2/Fe3O4/silver and TiO2/α-Fe2O3/silver nanoparticles, respectively, compared with their corresponding control samples. Moreover, both TiO2/iron oxide/Ag nanoparticle treated samples indicated an antibacterial efficiency of ≥ 99:99% against Staphylococcus aureus bacteria. Findings suggested that the developed magneto, bio and photo activities could be idealized, depending on the end use of the treated fabrics, through incorporation of different iron oxides in the prepared nanoparticles; magnetite providing the highest saturation magnetization and hematite the best self-cleaning toward degradation of methylene blue under sunlight irradiation. [ABSTRACT FROM AUTHOR]

Abstract: Nanoparticles of La0.8Sr0.2MnO3 (LSMO) with different particle sizes are synthesized by a very fast, inexpensive, reproducible, and environmentally friendly method: the microwave irradiation of the corresponding mixture of nitrates. The structural and magnetic properties of the samples are investigated by the X-Ray diffraction (XRD), Fourier transform infra-red (FT-IR) spectroscopy, field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), and magnetic (DC magnetization and AC susceptibility) measurements. The XRD study coupled with the Rietveld refinement show that all samples crystallize in a rhombohedral structure with the space group of R−3C. The FT-IR spectroscopy and FE-SEM images indicate formation of the perovskite structure of LSMO. The DC magnetization measurements confirm the decrease in the particle size effects on the magnetic properties, e.g. reduction in the ferromagnetic (FM) moment and increase in the surface spin disorder. Magnetic dynamics of the samples studied by AC magnetic susceptibility shows that the magnetic behavior of the nanometer-sized samples is well-described by the Vogel-Fulcher and critical slowing down laws. Strong interaction between magnetic nanoparticles of LSMO was detected by fitting the experimental data with the mentioned models. [Copyright &y& Elsevier]

Highlights: [•] FeSbO4 having minimum crystallite size 2nm was synthesized by sol–gel process. [•] Rietveld method and vibrational spectroscopy confirmed size and other properties. [•] SEM, XRD, UV, DSC, FT-IR and Raman spectra characterized the material. [•] First combined experimental and theoretical study on vibrational properties. [•] Significant advancement towards the fabrication of robust gas-sensor. [Copyright &y& Elsevier]

Zeolite NaA samples with varying concentration of Fe3+ ions have been prepared by wet chemical method. Based on powder X-ray diffraction, 29Si and 27Al MAS NMR and Fe3+ EPR investigations, the formation of nano-sized ferric oxide particles inside the larger α-cages of zeolite NaA has been established. Both Mössbauer effect and magnetization measurements carried out down to 4.5 K established the superparamagnetic behaviour of these Fe2O3 particles with a blocking temperature of ≈20 K, where the magnetization values showed deviation for the zero field cooled and field cooled samples and the appearance of a very narrow magnetic hysteresis loop below this temperature. For all Fe3+ containing samples the room temperature Mössbauer spectrum is a broad quadrupole doublet with chemical shift, δ ≈ 0.33 mm/s and quadrupole splitting, ΔE q ≈ 0.68 mm/s. Variable temperature 57Fe Mössbauer effect measurements exhibited magnetic features below the blocking temperature and at 4.5 K, the observed spectrum is a broad magnetic sextet characterized by an internal hyperfine field value of ≈504 kOe along with a very weak central superparamagnetic quadrupole doublet. [ABSTRACT FROM AUTHOR]

Abstract: Trinuclear cobalt(II) and copper(II) complexes of the deprotonated N-[2-hydroxy-1(R)-methyl-2(R)-phenylethyl]-N-methylglycine (R,R(−)(H2cpse)) or N-[2-hydroxy-1(S)-methyl-2(S)-phenylethyl]-N-methylglycine (S,S(+)(H2cpse)) were prepared from the corresponding mononuclear compounds [M(Hcpse)2]·nH2O with the acetyl amino alcohol derivative. The crystal structure of the trinuclear copper(II) [Cu3(R,R(−)cpse)3(H2O)3]·8H2O (5) consists of three Cu2+ atoms with distorted square pyramidal geometry, linked by bridging oxygens from the deprotonated alcohol group to form an equilateral triangular array. This compound displays an antiferromagnetic coupling attributed to intermolecular hydrogen bonding, allowing for super-exchange pathway. The iso-structural trinuclear cobalt(II) compound [Co3(S,S(+)cpse)3(H2O)3]·7H2O (6) presents a super-paramagnetic behavior. On the other hand, a polymeric copper(II) compound {K2[Cu2(S,S(+)cpse)2(SCN)2]·H2O} n (7) was obtained from previously reported trinuclear [Cu3(S,S(+)cpse)3(H2O)3]·8H2O. This polymeric structure involves potassium ions together with the thiocyanate molecules forming a helicoidal arrangement on the c axis, presenting a ferromagnetic behavior. [Copyright &y& Elsevier]

Abstract: Nanocrystalline Li0.5Fe2.5O4 ferrite particles were synthesized with an average crystallite size of 12.3nm and 5.7nm by chemical coprecipitation and reverse microemulsion technique respectively. Zero-field cooled (ZFC) and field cooled (FC) magnetization measurements at different magnetic fields and magnetic hysteresis loops at different temperatures have been measured. The non-saturation of M–H loops with a very low coercivity and remenance at room temperature confirms the presence of superparamagnetic (SPM) nature and single-domain ferrite particles. The blocking temperature (T B) has been found to shift towards the lower temperature region with the increase in applied magnetic field. It has been attributed to the reduction of magnetocrystalline anisotropy constant and blocking temperature dereases from 145K to 110K with increase in field from 50Oe to 1000Oe in the samples synthesized by microemulsion method. At high temperature, microemulsion synthesized nanoparticles show a maximum in magnetization versus temperature plot just below the Curie temperature (T C) which has been attributed to the cumulative effect of the change in anisotropy with temperature and particle size growth during the measurement. [Copyright &y& Elsevier]

Abstract: Stable magnetic magnetite nanoparticles (Fe3O4 NPs) were synthesized using the chemical co-precipitation method of ferrous (Fe2+)/ferric (Fe3+) mixed aqueous salt solutions in presence of well-defined biocompatible low generation (poly)amidoamine (PAMAM)-based dendrimers with end-grafted n ethylene glycol ether (n =1, 2, 9) moieties, accessible by means of straightforward consecutive divergent synthesis methodologies including addition and amidation cycles. Addition of NH4OH to the respective dendritic nanoreagent containing iron salt solution produced dendritic stabilized uniform shaped magnetite nanoparticles. The structural and magnetic properties of Fe3O4 NPs were analyzed by FT-IR spectroscopy, thermogravimetry (TG), X-ray powder diffraction (XRPD), transmission electron microscopy (TEM), and superconducting quantum interference device (SQUID) vibrating sample magnetometry (VSM). The coherence of affecting the average magnetite particle diameter in range of 5.6 (±1.4)–10.1 (±1.9)nm by the dendritic scaffold, the number and length of the attached ethylene glycol ether termini, as well as the adjusted stabilizer-to-Fe3O4 ratio is discussed along with their magnetic peculiarities. [Copyright &y& Elsevier]

Abstract: Ferrofluids are colloidal systems composed of a single domain of magnetic nanoparticles with a mean diameter around 30nm, dispersed in a liquid carrier. Magnetic Co(1−x)Zn x Fe2O4 (x=0.25, 0.50, 0.75) ferrite nanoparticles were prepared via co-precipitation method from aqueous salt solutions in an alkaline medium. The composition and structure of the samples were characterized through Energy Dispersive X-ray Spectroscopy and X-ray diffraction, respectively. Transmission Electron Microscopy (TEM) studies permitted determining nanoparticle size; grain size of nanoparticle conglomerates was established via Atomic Force Microscopy. The magnetic behavior of ferrofluids was characterized by Vibrating Sample Magnetometer (VSM); and finally, a magnetic force microscope was used to visualize the magnetic domains of Co(1−x)Zn x Fe2O4 nanoparticles. X-ray diffraction patterns of Co(1−x)Zn x Fe2O4 show the presence of the most intense peak corresponding to the (311) crystallographic orientation of the spinel phase of CoFe2O4. Fourier Transform Infrared Spectroscopy confirmed the presence of the bonds associated to the spinel structures; particularly for ferrites. The mean size of the crystallite of nanoparticles determined from the full-width at half maximum of the strongest reflection of the (311) peak by using the Scherrer approximation diminished from (9.5±0.3)nm to (5.4±0.2)nm when the Zn concentration increases from 0.21 to 0.75. The size of the Co–Zn ferrite nanoparticles obtained by TEM is in good agreement with the crystallite size calculated from X-ray diffraction patterns, using Scherer''s formula. The magnetic properties investigated with the aid of a VSM at room temperature presented super-paramagnetic behavior, determined by the shape of the hysteresis loop. In this study, we established that the coercive field of Co(1−x)Zn x Fe2O4 magnetic nanoparticles, the crystal and nanoparticle sizes determined by X-ray Diffraction and TEM, respectively, decrease with the increase of the Zn at%. Finally, our magnetic nanoparticles are not very hard magnetic materials given that the hysteresis loop is small and for this reason Co(1−x)Zn x Fe2O4 nanoparticles are considered as soft magnetic material. [Copyright &y& Elsevier]

Abstract: A synthesis route to /ZrO2/Fe3O4/WO3 solid acid catalysts with magnetism is reported through chemical co-precipitation method. The obtained solid acid catalysts are characterized in detail by X-ray diffraction, Different Scanning Calorimetry (DSC), Transmission Electron Microscopy (TEM), Vibrating Sample Magnetometer (VSM), N2 adsorption–desorption, Temperature-Programmed Pesorption (TPD) of ammonia. The results show that the introduction of WO3 and Fe3O4 strongly inhibit the phase transformation of zirconia and improve the thermal stability of zirconia. Furthermore, the obtained materials present super-paramagnetism and magnetism. The super acid exhibits high catalytic activity in forming fructone by condensation. [Copyright &y& Elsevier]

Spinel nanoferrites of composition Ni0.4Ca0.6Fe2O4 have been synthesized by sol-gel method and subsequently coated with intrinsically conducting polymers such as polyaniline and polypyrrole separately, using chemical oxidative polymerization technique. The characterization of the composites has been performed by X-ray diffraction and atomic force microscopy images. The room temperature DC electrical conductivity measurements are performed in order to understand the coating effectiveness and the nature of electrical conductivity of the composites. The Mössbauer spectroscopic studies reveal that the ferrimagnetic as well as super-paramagnetic states co-exist at room temperature (300 K) for all the samples which is found in good agreement with the DC magnetization measurement results, wherein the coercivity is observed in the M-H curves for all the samples at room temperature. [ABSTRACT FROM AUTHOR]

The magnetic behavior of nano-crystalline Ni0.5Cu0.5Fe2O4, synthesized by the co-precipitation method and their functionally coated nano-composites with polypyrrole has been studied. The nano-composite samples have been prepared by chemical oxidative polymerization of the monomer, pyrrole in presence of Ni0.5Cu0.5Fe2O4 nano-particles using ammonium peroxodisulphate as oxidant as well as initiator. The X-ray diffraction patterns confirm the formation of cubic spinel structure. The Mössbauer measurements reveal the quadrupole splitting as well as the magnetic hyperfine behavior of both the samples respectively at 300 K and 20 K. The DC magnetization measurements show that the samples are super-paramagnetic above the blocking temperature and the blocking temperature increases on polymerization. The increase in saturation magnetization and the blocking temperature in the case of polypyrrole coated nano-composites compared to the pristine nano-particle has been attributed to the surface spin ordering of nano-particles due to the crystal growth, ionic site exchange and the molecular level interactions at the surface. [ABSTRACT FROM AUTHOR]

Abstract: With crystallization at 850°C for 4h, LiMn2O4, β-wollastonite (β-CaSiO3), lithium silicate (Li2SiO3), Ca(Ca, Mn)Si2O6 and Li2Ca4Si4O13 phases were found in 25Li2O–8MnO2–20CaO–2P2O5–45SiO2 (LMCPS) glass ceramics. The (Li, Mn)ferrite phase was obtained in the iron oxide contained LMFCPS glass ceramic and Li2FeMn3O8 phase was found in that containing 8at.% Fe2O3. TEM investigations showed that (Li, Mn)ferrite particles dispersed in the β-wollastonite matrix (Li, Mn)ferrite particles, with an average size of 40nm, were found in the glass ceramics containing 4at.% Fe2O3. The (Li, Mn)ferrite particle sizes in the glass ceramics containing 8at.% Fe2O3 varied from a few μm to 5nm. The SQUID result showed that only the glass ceramic containing 4at.% Fe2O3 exhibited super-paramagnetic behavior at temperature 300K and ferromagnetic behavior at 4K. The LMCPS glass ceramic containing 8at.% Fe2O3 exhibited ferromagnetic behavior at both temperatures. [Copyright &y& Elsevier]

Abstract: The size distributions of precipitated Ni clusters on the surface of a LaNi5-based alloy immersed in alkaline solution (alkaline treatment) at 383K for 0–110min were precisely determined by combining superparamagnetic analysis and transmission electron microscopy (TEM) observations. The superparamagnetic analysis indicated that the diameters of the Ni clusters were smaller than ∼25nm in all samples, while their average values increased approximately from 5 to 9nm with increasing alkaline treatment time. The spatial distribution of the Ni clusters was successively observed by TEM, which agreed fairly well with the estimated size distribution by superparamagnetic analysis. Therefore, estimation of the actual size distribution of Ni clusters by superparamagnetic analysis was proved to be feasible. Based on the above results, a precipitation process for Ni clusters by alkaline treatment is proposed. [Copyright &y& Elsevier]

• NiO, CuO and NiO-CuO nanoparticles were synthesized via precipitation method. • The composite exhibited photoconductive property better than NiO but less than CuO. • Enhanced magnetic and antifungal properties were realized for the composite. Semiconductor nanocomposites containing two metal oxides with different functionalities have gained significant attention as they exhibit improved optical, electrical, magnetic and catalytic properties better than their single entities. The present work aims to synthesize NiO-CuO nanocomposite and to study its suitability for photoconductive sensor, soft magnetic materials applications and as antimicrobial agent. NiO, CuO and NiO-CuO nanoparticles were synthesized by precipitation method. X-ray diffraction (XRD) studies reveal the existence of cubic and monoclinic structured peaks of NiO and CuO in the nanocomposite. Ni-O and Cu-O related bands were observed from the Fourier Transform Infrared (FTIR) spectrum of the nanocomposite. The nanocomposite exhibits band gap between NiO and CuO. Photosensitivity of NiO improves when coupled with CuO. The nanocomposite possess enhanced ferromagnetic behaviour due to increased point defects, uncompensated spins and exchange coupling between Cu2+ and Ni2+ ions. CuO improved the antifungal ability of NiO against Aspergillus terreus (A. Terreus) fungi. [ABSTRACT FROM AUTHOR]

In this work, structural and magnetic properties of Ni 0.5 Mg x Zn 0.5-x Fe 2 O 4 (x = 0.0, 0.1, 0.2, 0.3, 0.4, 0.5) nanocrystalline ferrites synthesized via the co-precipitation method are reported. The ferrites are found to be at the nano-scale with sizes below 30 nm and seem porous in their general appearance. The structural properties were investigated using X-ray and Infrared (IR) spectra. X-ray Diffraction (XRD) patterns have been refined using the Rietveld method to find the lattice parameters. It was found that all these ferrites are a single-phase cubic spinel related structure belonging to the Fd-3m space group. Further, the positions, occupancy and Wyckoff's cationic position of the ions, in addition the lattice constant (a), the crystallite size (D) and the micro-strain of the composites have been analyzed and found to be affected by the variation of the Mg2+ ions concentration. The Vibrating Sample Magnetometer (VSM) technique showed that these nanoparticles are superparamagnetic with approximately impermanent magnetization of relatively high values. It was also found that the magnetization values of the Ni 0.5 Mg x Zn 0.5-x Fe 2 O 4 (0.0 ≤ x ≤ 0.5) system increase with the existence of the Mg2+ and the Zn2+ contents together (at x = 0.1, 0.2, 0.3, 0.4) due to the increase in the super exchange interaction happening between the Fe3+ and the Ni2+ ions resulting from the occupation of the Mg2+ and the Zn2+ ions (nonmagnetic) to exclusively the A-sites as indicated by the Rietveld's structural analysis. These composites are expected to be promising for biomedical applications due to their superparamagnetic property below 30 nm. Schematic diagram of the preparation process of the Ni 0.5 Mg x Zn 0.5-x Fe 2 O 4, (x = 0, 0.1, 0.2, 0.3, 0.4, 0.5) nanocrystalline ferrites. Image 1 • Structural and magnetic properties of the Ni–Mg–Zn–Fe 2 O 4 system have been discussed. • Rietveld method was used to obtain the lattice parameters using MAUD program. • NPs below 30 nm appeared fine homogeneous and porous in their general appearance. • Superparamagnetic NPs with relatively high magnetization for biomedical applications. [ABSTRACT FROM AUTHOR]