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Chemical state
About: Chemical state is a research topic. Over the lifetime, 2378 publications have been published within this topic receiving 78183 citations.
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TL;DR: In this article, photon energy dependent measurements in combination with argon-ion irradiation were employed to identify and separate surface and bulk contributions to the spectra of bulk metallic glasses.
Abstract: Bulk metallic glasses consisting of Fe, Mo, Cr, C, B, and Er have been investigated by x-ray photoelectron spectroscopy, aimed to elucidate the local atomic structure of the amorphous phase In order to examine the electronic properties of this class of material, photon energy dependent measurements in combination with argon-ion irradiation were employed to identify and separate surface and bulk contributions to the spectra The core levels suggest the presence of a carbon-rich surface layer with oxidized boron and metals, and metal carbides and borides in the bulk Exposure to molecular oxygen and annealing experiments probe the chemical reactivity of the material Formation of boron oxides at comparably low temperatures (300°C) might have consequences for the stability of the amorphous phase We observe variations in binding energy of the Fe 3p core level with respect to the alloy composition, which indicate changes in the chemical state of iron
7 citations
TL;DR: In this article, the structural and electronic characterization of carbon spheres obtained from a chemical vapor deposition synthesis process was analyzed in detail, in particular, electron microscopies and Raman spectroscopy help understanding the morphology and the graphitic-sp2 arrangement of the carbon atoms in the architectures.
Abstract: Carbon spheres of nanometric dimension are known since the first studies on the synthesis of fullerenes. Their shape originates from the curvature of a carbon sheet similar to fullerenes, but with numerous graphitic rings that regulate the inside structure and the formation of open edges at the surface. This paper focuses on the structural and electronic characterization of carbon spheres obtained from a chemical vapor deposition synthesis process. Two different sets of samples are analyzed in detail, in particular, electron microscopies and Raman spectroscopy help understanding the morphology and the graphitic-sp2 arrangement of the carbon atoms in the architectures. In addition, the iron catalyst used during the reaction process confers the carbon spheres a ferromagnetic response at room temperature. Therefore, both the structural properties of the samples and the active contribution of iron mark the difference in the measured photoresponse as well as in the electrochemical behavior. The X-ray photoelectron spectroscopy study addresses these points by giving information on the composition and the iron chemical state in the assembly. The collected results underline the advantages offered by this nanomaterial for sustainable applications.
7 citations
TL;DR: In this article , the effects of X-ray irradiation on change in the chemical state are sometimes ignored, which may impair the understanding of the environmental behavior of these elements, and therefore, methods for reducing potential error due to X ray irradiation are suggested, including using the minimum scan time, measuring uranium-containing samples first or independent of other samples, and using Xray of lower intensity.
7 citations
TL;DR: In this article, a hybrid electrochemical-thermal method was used to synthesize microcrystalline alumina (γ-Al2O3) powder, which was calcined for an hour at temperatures ranging from 60°C to 900°C.
Abstract: Microcrystalline alumina (γ-Al2O3) powder was successfully synthesized by hybrid electrochemical-thermal method. The as-synthesized powder was calcined for an hour at temperatures ranging from 60°C to 900°C. The crystallite size, morphology, and chemical state of the synthesized powders were characterized by powder XRD, TG-DTA, XPS, SEM/EDAX, TEM and FT-IR spectral methods. The effect of calcination temperature on crystallite size and morphology was assessed. Scanning electron photomicrographs show a cauliflower like morphology and EDAX measurement showed its chemical composition. Thermal behavior of as-synthesized product was examined. The TEM result revealed that, the particles are cauliflower in nature with diameter of 0.2–0.5 μm. The crystallite size increased with increase of calcination temperature. The electrochemically generated γ-Al2O3 powder was used to fabricate Zn-γ-Al2O3 composite thin films and its corrosion behavior was analyzed by anodic polarization, tafel extrapolation and electrochemical impedance spectroscopy. The results indicate that the Zn-γ-Al2O3 composite thin films have potential applications to corrosion protection.
7 citations
TL;DR: In this article, the authors have succeeded to fabricate a thin film consisting of nano-crystallites TiO on a substrate at room temperature by using the magnetron sputtering combined with the gas aggregation method which has the capability to deposit grown small particles and/or clusters of the desired compound material on the substrate in soft-landed mode.
Abstract: We have succeeded to fabricate the thin film mainly or entirely consisting of nano-crystallites TiO on a substrate at room temperature by using the magnetron sputtering combined with the gas aggregation method which has the capability to deposit grown small particles and/or clusters of the desired compound material on the substrate in soft-landed mode. The important experimental parameters to control the growth of TiO particles are identified as partial pressure of additional oxygen gas, growth-reaction distance Ltd, and LN2 cooling of growth chamber. The smallest averaged diameter of TiO nano-particles is 5.62 nm and size distribution being from 2 to 8 nm under 50 mm of Ltd. The compositional uniformity is confirmed by EDS and EELS. The chemical state of the film observed by Ti 2P XPS peak confirms the primarily growth of TiO and indicates the formation of minor content of amorphous Ti1-xOx and/or Ti1-xCx particularly at the surface of the film.
7 citations