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• Reorientation of magnetic moments as a consequence of elemental composition is seen. • Reorientation of magnetic moments as a consequence of elemental ordering is observed. • Difference between layered and alloyed nanowires is discussed. Anomalous deposition of multi-element nanowires continuously interests scientists to study such a system. In this paper, two types of magnetic nanowires were electrodeposited: multilayered and alloy-like. Fe-Co and Fe-Ni nanowires with various relative molar ratio were prepared by DC electrodeposition in aluminum oxide matrix, with a mean pore diameter of 140 ± 20 nm. The nanostructures were investigated in two states: released and within the matrix, using the following techniques: Scanning Electron Microscopy, Energy Dispersive X-ray spectroscopy, X-ray diffraction, Infrared, and Mössbauer spectroscopy. The Scanning Electron Microscopy showed that the length of Fe-(Co, Ni) nanowires is of the order of 3 µm and the diameter determined by the pores of the anodic aluminum oxide templates. The X-ray diffraction and Mössbauer spectroscopy also showed that the fabrication method allows for the obtainment of both multilayered as well as alloyed nanowires with tunable magnetic properties which depend on both the elements' relative ratio and its ordering. The magnetic texture observed by Mössbauer measurements demonstrated the almost random distribution of magnetic moments of iron in the studied samples which are rather unusual in layered systems. [ABSTRACT FROM AUTHOR]

We have investigated the magneto-optic properties of triangular and ellipsoidally-shaped islands. Preparation of the islands is done by soft nanosphere lithography and subsequent annealing. The change of the magneto-optic properties as a result of composition and shape of the islands is discussed. The spectral magneto-optic response of flat triangular island is found to be similar to bulk despite the nanometric size, only differing in magnitude. Ellipsoidally shaped island of the same lateral spacing, however, exhibit a change of sign in combination with an enhancement of the magneto-optic signal. Scattering effects are believed to be the origin for this behavior. • Soft lithography with PS balls for triangular island fabrication has been applied. • Sign changes of magneto-optical response as a consequence of the shape of the island have been observed. • Structures shape role in magneto-optical signal sign has been proved by round nanoparticles incorporation into the system. [ABSTRACT FROM AUTHOR]

In this paper, a new way of the preparation of core-shell magnetic nanowires has been proposed. For the modification Fe nanowires were prepared by electrodeposition in anodic aluminium oxide matrixes, in first step. In second, by wetting chemical deposition, shell layers of Ag, Au or Cu were obtained. Resultant core-shell nanowires structure was characterized by X-ray diffraction, infrared spectroscopy, transmission electron microscopy, and energy dispersive x-ray. Whereas magnetic properties by Mössbauer spectroscopy. [ABSTRACT FROM AUTHOR]

This paper describes preparation and characterization of magnetic core–shell nanoparticles with modulated magnetic core diameter and various thickness of the non-magnetic shell. Ag, Au and Cu are used as spacing layer metals. Nanoparticles were fabricated by the synthetic method based on modified seeds. During the preparation, the thicknesses of the core and shell were changed to control the influence of nanoparticles’ magnetic properties in respect to the composition and thickness of the spacer material. Obtained nanoparticles were examined by X-ray diffraction, transmission electron microscopy, infrared spectroscopy and differential scanning calorimetry. Magnetic properties of the nanoparticles were tested by Mössbauer spectroscopy. [ABSTRACT FROM AUTHOR]

This paper presents the studies of stability of magnetic core–shell nanowires prepared by electrochemical deposition from an acidic solution containing iron in the core and modified surface layer. The obtained nanowires were tested according to their durability in distilled water, 0.01 M citric acid, 0.9% NaCl, and commercial white wine (12% alcohol). The proposed solutions were chosen in such a way as to mimic food related environment due to a possible application of nanowires as additives to, for example, packages. After 1, 2 and 3 weeks wetting in the solutions, nanoparticles were tested by Infrared Spectroscopy, Atomic Absorption Spectroscopy, Transmission Electron Microscopy and X-ray diffraction methods. [ABSTRACT FROM AUTHOR]

Studies of the ferrite nanoparticles prepared by the chemical decomposition of iron chlorides with a various ratio ξ = Fe 3+ /Fe 2+ are herein presented. The microstructure and the magnetic properties have been studied by transmission electron microscopy (TEM), X-ray diffraction (XRD) and Mössbauer spectroscopy (MS). The TEM studies show that the nanoparticles have almost a spherical shape with the diameter of (12 ± 2) nm for all samples. The measured XRD pattern was mainly composed of lines which were indexed with a cubic spinel structure. The analysis of the Mössbauer data shows that the microstructure of the nanoparticles consists of the core formed by nonstoichiometric magnetite and maghemite shell. A small amount of hematite, probably on the surface of the nanoparticles with ξ = 1.75, 2.0, was detected. At temperatures T ≤ 150 K the spin canting of surface maghemite with ξ = 2.25 was observed while for the samples with ξ = 1.75, 2.0 such effect was suppressed by the presence of hematite on the surface of the nanoparticles. Infield Mössbauer spectra with ξ = 1.75, 2.0 show that magnetic moments of the magnetite/maghemite core are parallel while magnetic moments of the surface hematite are perpendicular to the direction of the external magnetic field. [ABSTRACT FROM AUTHOR]

Highlights: [•] Core–shell nanoparticles with various shell layers were fabricated. [•] The influence on magnetic properties from layer composition was observed. [•] The influence on quality of layer from their composition was tested. [ABSTRACT FROM AUTHOR]

Highlights: [•] Stability of magnetite nanoparticles in environmental solutions was tested. [•] The most aggressive model solutions were determined to be citric acid, acetic acid and white wine. [•] The chosen model solutions dissolve magnetic core (acids) or modifies mostly particle surface (wine). [ABSTRACT FROM AUTHOR]

Highlights: [•] Stability tests of core–shell nanoparticles were performed. [•] Various durability in studied solutions was observed. [•] The influence on magnetic properties from wetting solution was observed. [Copyright &y& Elsevier]

Highlights: [•] Organophosphorous compound modification of magnetic nanoparticles has been obtained. [•] Successful connection with trypsin via organophosphorous compounds has been tested. [•] Influence on modification from particles coating layer have been tested. [ABSTRACT FROM AUTHOR]

Highlights: [•] Organophosphorous compound modification of nanowires has been obtained. [•] Successful connection with trypsin via organophosphorous compounds has been tested. [•] Influence on modification from wires surface layer has been tested. [ABSTRACT FROM AUTHOR]

The magneto-optical properties of 14-nm CoAg core-shell nanoparticles ( x=0.7, 0.8, and 0.35) deposited on different substrates are investigated at room temperature in the photon-energy range from 0.8 to 4.8 eV. Particles with low Ag content show spectra very similar to pure Co nanoparticles while particles with high Ag content have totally different features, where the Ag plasma edge dominates the spectra. The spectral features of the polar Kerr rotation depend on particle composition. The ageing process and development of an oxide layer influence the particles' core-shell structures and magnetization curves. Co-rich particles exhibit lower resistance to the oxidation process as compared to Ag-rich ones. The quality of the nanoparticles was checked by transmission electron microscopy in respect of time scale. [ABSTRACT FROM AUTHOR]

Abstract: The iron nanowires were obtained by DC electrochemical method in nanoporous anodic alumina templates (AAO). For stability tests these materials were placed in different solutions: white wine, citric acid, 0.9% NaCl, distilled water and ethanol for a 1–3week time period. The results of such treatment (solubility or possible changes on the surface) of the Fe nanowires were measured by IR (infrared spectroscopy), ASA (atomic absorption spectroscopy), TEM (transmission electron microscopy), XRD (X-ray diffraction) and DSC (differential scanning calorimetry) methods. [Copyright &y& Elsevier]

Abstract: Mössbauer measurements were carried out in order to study the influence of the transition metal substitution TM/Fe (where TM = Co, Ni, Mn, and (TM) x Fe3−x O4) ranging from 0.1 to 0.9 on the morphology and magnetic properties of ferrite nanoparticles. Chemically prepared magnetite nanoparticles with 13 nm were used as a reference material. The Mössbauer spectrum of the initial magnetite sample show a well-resolved magnetically split patterns connected with tetrahedral (A) positions and octahedral (B) positions. For low concentrations of TM, the relative intensities of the sextet that comes from the iron B position decrease. This means that the Co, Ni, Mn atoms are located preferentially in the B-site of the magnetite. However, the qualitative analysis of the spectra also suggests that Mn and Ni partially occupy the A-site. The increase of the concentration of the substitution transition metal causes broadening of the magnetic part of the spectra and appearance of a doublet in the central part of spectra for all samples. TEM studies show that the incorporation of the Me atoms into the structure causes a decrease of the average particle size. This is also confirmed by XRD. This also means that the blocking temperature decreases and for about Ni/Fe = 0.8 and TM/Fe = 0.9 (for Mn and Co) reaches room temperature. In the case of the nominal 0.9 substitution by Ni, a pure superparamagnetic state is observed, while for Co and Mn some of the particles are still below the blocking temperature, in agreement with the TEM studies. [Copyright &y& Elsevier]

Abstract: In the present study Fe3O4 magnetic nanoparticles were synthesized by coprecipitation of Fe2+ and Fe3+ from chlorides. In the next step magnetite–gold core–shell nanoparticles were synthesized from HAuCl4 using an ethanol as a reducing agent. Finally, magnetic nanoparticles were functionalized by hexadecanethiol. The immobilization of biological molecules (trypsin and glucose oxidase) to the thiol-modified and unmodified magnetite–gold nanoparticles surface was tested. The resulting nanoparticles were characterized by infrared spectroscopy, differential scanning calorimetry, Mössbauer spectroscopy and transmission electron microscopy. [Copyright &y& Elsevier]

Abstract: Silver and ferrite nanotubes were obtained in nanoporous alumina templates (AAO) of 200nm diameter by wetting chemical deposition followed by thermal crystallization. Iron filling in the nanotubes was fabricated by DC electrodeposition. Step by step fabrication in AAO was followed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) techniques. The core–shell nanowires were removed from the templates and verified by TEM and energy dispersive spectroscopy (EDS) techniques. Metallic (Ag) surfaces of nanowires were functionalized with alkenothiols terminated by methyl groups. Ferrite nanotubes were functionalized to –NH2 groups on the surface. In addition, these groups were bonded to protein–trypsin in two ways: covalently bonded to amine groups by glutaraldehyde and noncovalent absorption to alkenothiols. All the modifications were observed by infra-red spectroscopy (IR). [Copyright &y& Elsevier]

The ferrite magnetic nanoparticles with core-shell structures were obtained in two step preparation process. The Mössbauer spectra obtained for particles of pure maghemite or magnetite and two layered core-shell one the magnetite on maghemite and maghemite on magnetite are very different from each other. The presented results show that interparticle and intraparticle interaction plays important role in overall magnetic properties as well. [ABSTRACT FROM AUTHOR]

Abstract In presented in this paper studies, nanowires of pure metallic Fe, and one modified at the surface with iron oxide, Cu, and Ag layers were examined for its resistance in several environmental solutions (wastewaters, river water, and milk). Tests included investigations of the stability of nanowires in these solutions, and therefore their potential applicability as water filters, or food storage sensors, constituents of packages, etc. On the other hand, it shows its potential circulation in a human environment before final degradation. Nanowires were electrodeposited in the alumina oxide matrix and their diameter was determined by the pore size to be around 140 ± 20 nm. The length of nanostructures is adjustable by deposition time up to few μm. Nanowires physicochemical properties after treatment in mentioned solutions were measured by transmission electron microscopy, infra-red spectroscopy, and X-ray diffraction. Solutions after the experiment were analyzed by flame atomic absorption spectroscopy. Interaction with selected solutions shows that the highest concentration of Fe was found in milk and treated sewage and Ag only transfers to untreated wastewater and Cu was found in significant amounts in milk and untreated sewage. In addition, metallic layers prevent dilution of Fe core with the exception of two cases: untreated sewage with Ag shell, and milk with Cu shell. The durability tests of nanowires in environmental liquids and its resistance to real solutions as well as the dissolution was established. The indication of recycling processes of nanowires was achieved. Highlights • The durability tests of nanowires in environmental liquids was done. • The resistance of nanowires to real solutions was established. • The influence of environmental liquids on the dissolution of nanowires was tested. • The indication of recycling processes of nanowires was achieved. [ABSTRACT FROM AUTHOR]

• Mn 1-x CoFe x Ge alloys are double phase with TiNiSi-type orthorhombic structure and Ni 2 In-type hexagonal structure. • Fe atoms are located in both Mn and Co crystallographic positions in orthorhombic and hexagonal phase with almost equal probabilities. • Fe atoms located in hexagonal structure show, that induced hyperfine magnetic field in Mn position is much higher while on Co position smaller then applied external magnetic field. • An increase in the concentration of Fe atoms impurity in the alloy causes stabilization of the hexagonal structure at the expense of the orthorhombic structure. The phase analysis, site occupancy, and hyperfine fields of Mn 1-x CoFe x Ge alloys (x = 0.01, 0.02, 0.05, 0.10) after annealing procedure are presented. Mössbauer spectroscopy was performed with and without an external magnetic field of B = 1.3 T parallel to the beam direction at room temperature. RT X-ray diffraction shows that Mn 1-x CoFe x Ge compound is two phases of Ni 2 In type hexagonal structure and TiNiSi type orthorhombic structure. Samples with × = 0.01, 0.02 and 0.05 exhibit (pre)dominant contribution of the orthorhombic structure while for × = 0.10 the amount of hexagonal phase increases significantly. In the series of alloys, the lattice parameters and the unit cell volume remain weakly sensitive to Fe concentration at both phases. The measured Mössbauer spectra are superpositions of two doublets which come from the Fe atoms located in hexagonal structure and two broad sextets of Fe orthorhombic structure origin. The values of isomer shift and quadrupole splitting do not change with increasing iron content. Using information about the composition of local environment and measured values of isomer shift, we identify the origin of individual subspectra, and site occupation of Fe atoms in the alloy. The Mössbauer measurements carried out in external magnetic field shows that induced hyperfine magnetic field in the hexagonal structure is much higher for Fe at Mn sites than the observed for Fe at Co sites. Analysis of sextets shows that magnetic moments of Fe tend to arrange along the external field direction with almost the same values of about 0.87 µ B. [ABSTRACT FROM AUTHOR]

• Mn 1−x CoFe x Ge alloys are double phase with Ni 2 In-type hexagonal structure and TiNiSi-type orthorhombic structure. • Fe atoms are located in both Mn and Co crystallographic positions in hexagonal phase with almost equal probabilities. • Fe atoms located in hexagonal structure show, that induced hyperfine magnetic field in Mn position is much higher while on Co position smaller then applied external magnetic field. The crystal properties, site occupation and hyperfine fields of Mn 1−x CoFe x Ge (x = 0.01, 0.02, 0.05, 0.10) alloys after melting are presented. The X-ray diffraction and Mössbauer spectroscopy, without and with external magnetic field of B = 1.3 T parallel to beam direction, were carried out. X-ray diffraction shows that Mn 1−x CoFe x Ge (x = 0.01 and 0.02) alloys are double phase with Ni 2 In-type (space group P 6 3 /mmc) hexagonal structure and TiNiSi-type (space group Pmna) orthorhombic structure. For higher Fe concentration (x = 0.05 and 0.10) the single hexagonal phase is observed. The Mössbauer spectra are superposition of two doublets which come from the Fe atoms located in hexagonal structure and additional broad sextet originated from Fe in orthorhombic structure for samples x = 0.01 and 0.02. The analysis of Mössbauer spectra shows that doped Fe atoms are located in both Mn and Co crystallographic positions in hexagonal phase with almost equal probabilities. The results show that values of isomer shift and quadrupole splitting do not change with increasing iron concentration. For hexagonal structure the isomer shift is equal to (0.30 ± 0.05) mm/s for Fe in Co and (0.49 ± 0.05) mm/s for Fe in Mn position. The quadrupole splitting for hexagonal structure are equal to (0.79 ± 0.05) mm/s and (0.87 ± 0.05) mm/s for Fe in Co and Mn site, respectively. The Mössbauer measurements carried out in external magnetic field for iron atoms located in hexagonal structure show, that observed induced hyperfine magnetic field on Fe in Mn position is much higher while on Fe in Co position smaller then applied external magnetic field. [ABSTRACT FROM AUTHOR]

The influence of the surface modification on the magnetism of 4–14 nm sized core and core/shell gallium ferrites obtained by different preparation methods (Massart's and thermal decomposition from acetylacetonates) was studied. The physical properties of GaxFe3-xO4 were investigated in a wide range of Ga admixtures 0 ≤ x ≤ 1.5. Ga ions location at 8a or/and 16d positions of a spinel structure depends on the synthesis method and has a pronounced effect on the superparamagnetic properties of nanoparticles. Magnetization and Mössbauer experiments show the dominant superparamagnetic contribution for the nanoparticles with x > 0.8 with the blocking temperature TB significantly below 200 K. Surface-modified nanoferrites disclosed spontaneous magnetization that does not exceed 60 emu/g. [ABSTRACT FROM AUTHOR]

Abstract: In this work magnetic nanowires Fe and Co were obtained by the electrodeposition method (DC and AC respectively) in anodic alumina template (AAO) with 200 nm pore diameter. The surfaces of both types of the magnetic nanowires were successfully chemically modified using 1-hexadecanethiol. Optional deposition method in the presence of external magnetic field obtained by permanent magnets in two orientations was conducted resulting in wires with different morphology. The quality of alumina pores was examined using SEM (Scanning Electron Microscopy). Free and clean nanostructures were studied by TEM (Transmission Electron Microscopy) techniques. In addition, the EDS (Energy Dispersive Spectroscopy) analysis was done to prove the composition of the obtained material. The results of functionalization were observed by IR (infra-red) spectroscopy. [Copyright &y& Elsevier]

We have succeeded in synthesizing orthorhombic Ga(1_X)Fe(1+X)03 (-0.05 ≤ x ≤ 0.5), hexagonal GayFe(2-y)O3 (0 ≤ y ≤1.8) and cubic Ga(1+Z)Fe(2-Z)04 (--0.1 ≤ z ≤ 0.8) nanograins of gallium ferrites using conventional precursors and an organic environment of Pechini scenario under atmosphericpressure conditions (SG method). Phase composition and homogeneity were analyzed using X-ray diffraction. Small angle neutron scattering disclosed ellipsoidal particle shapes of gallium iron oxides (GFO) crystallizing in orthorhombic (o-GFO) and hexagonal (h-GFO) symmetry and parallelepiped shapes of Ga(1+y)Fe(2-y)O4 (c-GFO) grains. Despite local agglomeration among the magnetic grains, the scanning electron microscopy and transmission electron microscopy images point to faced-elliptical shapes. The Mössbauer spectroscopy with magnetization measurements was carried out in the temperature range of 5-295 K. The analysis of gallium ferrites magnetism demonstrates that iron atoms locate with various probabilities in crystallography positions and the spontaneous magnetization preserves up to room temperature (RT). [ABSTRACT FROM AUTHOR]

In presented paper magnetite nanoparticles (MNP), with various types of surface stabilizers has been fabricated. Nanostructures were obtained by thermal decomposition of Fe(acac) 3 precursor in organic solutions. Five types of long-chain carboxylic acids and four types of amines were used for stabilization of nanoparticles. It was also tested, how surfactant concentration influences on the nanoparticles morphology and its properties. Obtained nanoparticles were examined by X-ray diffraction, Transmission Electron Microscopy and Infrared spectroscopy. Magnetic properties of the nanoparticles were tested by Mössbauer spectroscopy and Vibrating Sample Magnetometry. Magnetization and Mössbauer measurements show how stabilizer layer influence the magnetic state of particles. It has been analyzed the importance of the C C chain length, its spatial configuration or compound properties on magnetic state of the particles for few examples. From tested agents as a best, giving most even in shape and well distributed nanoparticles, hexylamine was selected. [ABSTRACT FROM AUTHOR]

The effects of the external magnetic field presence on the electrocrystallization of Fe/Ni alloy have been investigated. It is reported that the magnetic field superposed perpendicular to the electrode surface has an influence on the Fe/Ni alloy growth. It is found that the Fe content increases over the entire Fe/Ni solution deposition and the layer morphology strongly depends on the bath composition. Samples were characterized by X-ray diffraction, scanning electron microscopy, energy dispersive X-ray, X-ray fluorescence. [ABSTRACT FROM AUTHOR]

One of the most popular nuclear probes, 57 Fe is used for the investigation of orientations of hyperfine fields and also for the determination of other important properties. In particular, the orientation of iron magnetic moments can be unambiguously determined, including its signs. Experiments with polarized radiation are presented with regard to selected systems. Orientation of electric field gradient is used for acquiring information about the shape of the texture-free spectra. Applications on the analysis of iron-based superconductors are presented. [ABSTRACT FROM AUTHOR]

[Display omitted] • The influence of synthetic procedure on nanoparticles growth was tested. • The influence of dopant concentration on nanoparticles growth was established. • The correlation between particles growth condition and magnetic properties was achieved. The studies presented in this paper show the results of synthesis and physicochemical characterization of modified ferrite nanoparticles, which can be described by the general formula M x Fe 3-x O 4 (where x = 0.15 or 0.45) doped with Al3+, Cr3+, Cu2+ and Zn2+ ions. The nanoparticles were obtained through procedures using either water or organic environment. The aim of this study was to determine the influence of synthetic routine and doping on the quality of the obtained structure, morphology and magnetic properties of nanoparticles. Additionally, doping concentration of selected elements is a crucial influence on the crystallinity and magnetic properties of the obtained nanoparticles. Doped nanoparticles were synthesized by two chemical methods: co-precipitation of iron chlorides in a basic solution and thermal decomposition of iron(III) acetylacetonate in an organic high-boiling solvent. Obtained nanoparticles were characterized by transmission electron microscopy, energy dispersive X-ray, X-ray diffraction, porosimetry, infrared spectroscopy and Mössbauer spectroscopy. [ABSTRACT FROM AUTHOR]

• The influence of fruit and vegetable extracts on nanoparticles growth was observed. • The influence of particle synthetic procedure and pH on core composition was established. • The correlation between used extract and antibacterial activity was observed. A proper understanding of silver (Ag) nanoparticles properties is fundamental for developing new antimicrobial agents. In this study, Ag nanoparticles were obtained by green synthesis methods using natural reducing agents present in extracts of apples, oranges, potatoes, red pepper, white onion, garlic and radish. The antimicrobial properties of respective nanoparticles, expressed as the minimum inhibitory concentration, were assessed against Staphylococcus aureus, Bacillus cereus, Escherichia coli, and Candida krusei. Characterization of Ag nanoparticles was done with the application of transmission electron microscopy, X-ray diffraction and UV–vis spectroscopy. The obtained results led to the conclusions that in each extract (pH from 2.1 to 6.2) were obtained specific particles (size from 9 to 30 ± 2 nm) with different antimicrobial activity. Our study indicates that plant extracts gives the Ag nanoparticles specific properties, yet the best antimicrobial properties show nanoparticles obtained in the presence of potato extract. [ABSTRACT FROM AUTHOR]

The magnetic nanoparticles with core diameter 10 nm were modified by poly-L-lysine to bind antibody for cancer cell detection. Prepared biocompatible magnetic fluid (MFPLL) was characterized by dynamic light scattering method to obtain the particle size distribution. The microstructure of the MNPs and MFPLL samples were studied by transmission electron microscopy, X-ray diffraction and Mössbauer spectroscopy. Magnetic properties of the samples were measured by SQUID magnetometer and superparamagnetic behaviour of the samples was confirmed. [ABSTRACT FROM AUTHOR]

Abstract: Fretting experiments with an austenitic pin on a martensitic disc were performed. X-ray diffraction revealed that a part of the austenite pin was transformed into a martensite layer. The martensite is covered by a layer of Fe–Cr–Ni oxides, detected by the Mössbauer spectroscopy. Martensite and Fe-oxide, originating from the spinel structure, were identified in the debris powder. Obtained results indicate that the crystal structures of the Fe-oxides produced during fretting are highly defected. This is the cause of the observed superparamagnetic properties, broad diffraction maxima, and differences between predicted and observed Bragg spot intensities. [Copyright &y& Elsevier]