Cobalt ferrite (CFO) is a promising candidate for magnetostrictive applications like actuators or sensors. We have recently shown that uniaxial magnetic anisotropy can be induced in CFO by reactive sintering using spark plasma sintering (SPS), which leads to an improvement of its magnetostrictive properties. However, the origin of the anisotropy and the formation mechanism remain unexplained so far. In this study, different SPS processes have been conducted to determine which parameter is responsible for the induced uniaxial anisotropy. We demonstrate that the magnetic anisotropy arises during the cooling step when done under SPS's uniaxial compression. In addition, we also investigate the fundamental origin of the magnetic anisotropy induced during the SPS process. We show that the polycrystalline anisotropic cobalt ferrite obtained after SPS exhibits no texture. However, the SPS samples turn isotropic after being annealed in air at 400 degrees C/2 h, as shown by magnetic and magnetostrictive measurements. A change in ionic distribution after the annealing is also observed by Mossbauer spectroscopy. Our findings suggest that the induced magnetic anisotropy results from the ionic distribution of the Co2+ in the CFO's spinel lattice, a mechanism previously observed in magnetic annealed CFO. This study advances the in-depth understanding of the relationship between SPS processing and magnetic properties of cobalt ferrite.

Electroless plating of magnetic materials on catalytically active noble metal seeds is a powerful tool to design highly efficient recyclable catalysts. For the electroless plating procedure of metallic nanotubes in porous polymer templates, a sensitisation and activation process of the template is necessary. Therefore, metallic seeds are created on the surface of the polymer, which then enable the selective heterogeneous nucleation of a metal film on the template's surface. By choosing the metals for seeds and structures wisely, different functional materials can be purposefully combined. In this work magnetically recoverable catalysts were designed, which consist of magnetic NiCo nanotubes as carrier for catalytically active Pd seeds. The synthesised catalyst structures were thoroughly characterised by SEM, TEM, EDX, XRD, XPS, ICP-OES, VSM and then tested in the 4-nitrophenol reduction reaction, which was monitored by UV-Vis spectroscopy. After the reaction the structures were recycled and reused without a decrease in activity.

Co3O4 samples have been deposited using RF-magnetron sputtering from an oxide target. In situ x-ray and ultraviolet photoelectron spectroscopy and x-ray diffraction have been carried out to identify the phase and composition of the films. The work function of Co3O4 films showed variation of about 1 eV depending on the oxygen content of the sputter gas while the Fermi level position in the band gap was invariant towards different deposition parameters. Optical transmission spectroscopy in the UV/VIS/NIR regime showed two optical transitions at 0.8 eV and 1.7 eV. However, the optical absorption from these transition does not seem to aid in the conduction of charge carriers as has been revealed by conductivity measurements in a linear 4-point-setup. Diodes were prepared in a glass vertical bar FTO vertical bar TiO2 vertical bar Co3O4 vertical bar NiO vertical bar Au-stacking geometry. They show poor photovoltaic behaviour with a short-circuit current of 0.33 mA cm(-1) and an open-circuit voltage of 0.15 V, resulting in an overall efficiency of eta = 0.01%. The limitation of Co3O4 as an absorber in an All-Oxide solar cell can be related to poor transport properties combined with defect states in the band gap and Fermi level pinning at interfaces.

Layered stacks of the structure Si(100)/Ni/BCxNy were produced by physical (Ni) and chemical (BCN) vapor deposition. The BCN layers were deposited at temperatures of 200, 300, 400, and 500 °C. The resulting samples were characterized by ellipsometry, X‐ray photoelectron spectrometry, secondary ion mass spectrometry, atomic force microscopy, and X‐ray reflectometry. The formed structures of the samples synthesized at 200 and 500 °C, respectively, were determined. For the synthesis temperature of 200 °C, compounds with Ni–C bonds were found at the interface Ni/BCxNy. For the sample produced at 500 °C, compounds with Ni–Si bonds were identified, dispersed as particles or droplets in the corresponding interface. Copyright © 2015 John Wiley & Sons, Ltd.

This paper reports the results of investigations on manufacturing lightweight aggregates from sand sludge with zeolitic rocks added to decrease the foaming temperature. Sand sludge is a waste product from crushing and screening plants for sand and gravel production. Introduction of 20% zeolitic rock into the raw mix composition reduces the temperature required to produce lightweight aggregates by 50°C and improves their physical–mechanical characteristics. Lightweight aggregates using sand sludge with zeolitic rocks added have porous structures, with a total porosity of 60–70%; this material is recommended for use as lightweight aggregates for concrete and as heat-insulating filling.

We report experimental evidence of a long-range superconducting proximity effect in polycrystalline Co nanowires in contact with a superconducting W-based floating electrode (inducer). For electrical resistance measurements, voltage leads were connected to the Co nanowire on both sides of the superconducting inducer at a distance of 7.2 μm. We observed a 28% reduction of the nanowire resistance when sweeping the temperature below the inducer's transition temperature Tc = 5.2 K. Our analysis of the resistance data shows that the superconducting proximity length in polycrystalline Co is as large as 1 μm at 2.4 K, attesting to a long-range proximity effect. Moreover, this long-range proximity effect is insusceptible to magnetic fields up to 11 T, which is indicative of spin-triplet pairing. Our results provide evidence that magnetic inhomogeneity of the ferromagnet enlarges the spatial extend of the spin-triplet superconducting proximity effect.

A dependable and mild deposition procedure for the first electroless synthesis of platinum nanotubes in ion track etched polycarbonate was developed. It utilizes ethylenediamine to adjust the reactivity of Pt(IV) towards reduction and allows the controlled deposition of nanoscale platinum films, wires and tubes at room temperature. Single crystal structure determination proves the formation of Pt(II) as a side product next to elemental platinum. Highly polycrystalline nanostructures of 100 to 900 nm diameter and up to 30 mm length were obtained and characterized by TEM, SEM, EDS and XRD. The platinum nanotubes showed high activity in the electrooxidation of methanol in acidic environment. To illustrate the possibilities for synthesizing bimetallic nanotubes in the presented system, ruthenium was introduced by electroless and spontaneous deposition methods. The corresponding surface-normalized current densities are strongly dependent on the preparation method and can surpass commercial fuel cell catalysts, confirming the efficiency and flexibility of electroless metal plating in the preparation of nanomaterials.

Iron disilicide synthesis by mechanical alloying was performed. epsilon-FeSi, alpha-Fe1-xSi2, amorphous FeSi2 were formed with relative intensities depending on the milling period. beta-FeSi2 phase was formed after annealing the gridded powder at the temperature where this phase is stable. Mossbauer spectroscopy and X-ray diffraction methods were applied to determine the different phases formed. The morphology of the resulting particles was observed by high resolution scanning electron microscopy. The effect of the milling on bulk iron-silicide samples was and studied chemical effects of the ball milling on Fe-Si-2 systems have been studied. (C) 2010 Published by Elsevier B.V.

Series of Fe3O4/MgO(001) and Fe3O4/Fe/MgO(001) films (single- and hi-layer films, respectively) with a total layer thickness in the range of 20 divided by 150 nm were investigated by the Rutherford backscattering spectrometry (2 MeV He+ ion beam), by the Rutherford backscattering spectrometry channeling experiments (1.5 MeV He+ ion beam). Depending on the layer thickness of each layer and the film geometry, a single Fe peak and/or a double-anomaly feature was revealed in the Rutherford backscattering spectra. For all films no magnesium presence in the surface layer was observed. For both single- and hi-layer films with a total layer thickness less than 60 nm only one minimum was observed in the channeling curves, while a double minimum was revealed for the bi-layer films with a larger thickness. X-ray reflectometry measurements have revealed that the film density is the same as that of the bulk one.

We recently found that stabilizing agents have a strong effect on the interface structure of sol-gel deposited coatings. In this work we investigated the influence of the stabilizing agents hydroxypropyl cellulose (HPC) and acetylacetone (acac) on the protection performance and structure of protective zirconium oxide coatings which were deposited from zirconium-tetrapropoxicle onto iron samples and heated at 675 K.The crystalline structure of the films was characterized with X-ray diffraction (XRD) and transmission electron microscopy (TEM). The element distribution and chemical composition was studied with energy dispersive X-ray spectroscopy (EDX) and secondary ion mass spectrometry (SIMS). Film porosity and protection performance were measured electrochemically with potentiodynamic scans. XRD measurements revealed a higher amount of crystalline zirconium oxide on the surface for acetylacetone coatings than for HPC. However, the SIMS depth profiles showed a thicker mixed iron-zirconium oxide layer in the case of HPC samples. Although the electrochemical results of acetylacetone films indicated a good protection with low film porosity, the dissolution currents of the HPC coatings were still two orders of magnitude lower than for acac. This means, with the use of HPC the protection ability of zirconium coatings on iron can be improved significantly. (C) 2009 Elsevier B.V. All rights reserved.

LiPON (lithium-phosphorous-oxynitride), a solid state electrolyte for all-solid state Li ion batteries, was characterised in detail by XPS core level analysis. Different compositional structures were found for depositions at different sample temperatures. As known, the replacement of bridging oxygen by nitrogen plays an important role and the nitrogen XPS signal can be divided into two emission lines at different binding energies. These details have already been analysed in dependence on the deposition power and nitrogen pressure during deposition.In this contribution we have investigated the LiPON deposition at different temperatures by XPS and impedance measurements. Different conductivity values could be linked to structural differences that were investigated by XPS core level analysis. Additionally, the activation energies were compared for the electrolytes obtained for depositions at different substrate temperatures. (C) 2010 Elsevier B.V. All rights reserved.

Sol–gel coatings were deposited from a Phenyl-triethoxysilane precursor for corrosion protection on magnesium samples. Film porosity was measured with potentiodynamic scans and the coating's structure was characterized with secondary ion mass spectrometry and X-ray diffraction analysis. At the interface between substrate and coating a magnesium silicate layer was found which was formed by interdiffusion during the deposition process. The coated samples showed a good corrosion resistance and low porosity after heating at comparatively low temperature.

The interface reactions in an epitaxial 10 nm-thick Fe3O4/MgO(0 0 1) film were investigated by using Rutherford Backscattering spectrometry (RBS), channeling (RBS-C) and X-ray reflectometry (XRR). The as-grown film had a good crystallinity indicated by the minimum yield and the half-angle value for Fe, respectively, χmin(Fe) = 22% and ψ1/2(Fe) = 0.62°. Annealing the films under partial argon pressure up to 600 °C led to a large enhancement of Mg out-diffusion into the film forming a wustite-type phase, but the total layer thickness did not change much. Ion irradiation of the film by 1 MeV Ar ion beam caused a strong Fe ion mixing resulting in a large interfacial zone with a thickness of 23 nm.

Epitaxially-grown Fe3O4(001) thin films by reactive deposition on MgO(100) substrates were studied using low-energy electron diffraction (LEED), conversion electron Mössbauer spectroscopy (CEMS), Rutherford backscattering spectrometry (RBS), channeling (RBS-C) experiments and X-ray reflectometry (XRR). No visible influence from the ion irradiation of the samples on the CEMS spectra was found, while surface oxidation of the samples was observed after exposure to the atmospheric pressure. RBS analysis indicated the presence of magnesium with an average amount of 3% in the films. RBS-C experiments yielded a value of 22% for the minimum yield of Fe and a value of 0.62° for the half-angle for Fe in the film indicating a good crystal quality of the films. The value for film-thickness obtained from XRR is in a good agreement with that from RBS and the nominal value.

The authors have measured the field emission properties of freestanding bare and Au-coated Ni nanowires randomly distributed on thin metallic substrates. The nanowires of uniform length and diameter were grown in the etched ion-tracked pores of polycarbonate membranes by electrochemical deposition. While bare Ni samples yielded only 1.6×104emitters∕cm2 at 10V∕μm, Au coating of the Ni nanowires improved the emission site density to 1.4×105∕cm2 at 5V∕μm and about 1.6×106emitters∕cm2 at 18V∕μm. Average field enhancement factors β of 331 for bare Ni and 302 for Au-coated Ni nanowires correspond well to their cylindrical shape in the scanning electron microscope images. Stable Fowler-Nordheim-like emission was obtained on average up to currents of about 0.4 and 8μA for bare and Au-coated Ni nanowires, respectively. Locally measured I-V curves, maximum current Imax, and derived β values hint for the clustering of nanowires.

We have studied the contact formation on CdTe surfaces following the technologically applied procedure. The electronic properties of wet chemically etched CdTe surfaces has been investigated with photoelectron spectroscopy. For the characterization of the morphology, structure, and elemental distribution in the etched layer atomic force microscopy, scanning electron microscopy, grazing incidence x-ray diffraction, and secondary ion mass spectroscopy have been used. Etching of the samples has been performed in air and in an electrochemistry chamber directly attached to the UHV system. In both cases the formation of an elemental polycrystalline Te layer with a thickness of about 80 Å is detected. For comparison, a thin Te layer has been deposited by physical vapor deposition onto a CdTe substrate. We determine a valence-band offset of ΔEVB=0.5±0.1 eV, independent of the preparation of the interface.