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Core-shell and multilayered nanoparticles based on magnetite core with different metallic spacing and over-layers are prepared in one pot synthesis and characterized. The spacer layers were made from Au, Cu or Ag precursors. The nanoparticles were fabricated by a modified chemical seed based method. The obtained nanoparticles were examined by X-ray diffraction, Energy-dispersive X-ray spectroscopy, Transmission Electron Microscopy, Differential Scanning Calorimetry and Infrared spectroscopy. Magnetic properties of the nanoparticles were tested by Mössbauer spectroscopy and Magnetometry. Magnetization and Mössbauer measurements show that the presence of the metallic layers influences the magnetic state of the particles. XRD and EDX confirm layered structures of nanoparticles. Proposed synthesis allows for fabrication of layered particles with controlled morphology and register properties changes which are related to the nature of each subsequent layer. [ABSTRACT FROM AUTHOR]

• 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]

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 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]

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]

• 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]

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]