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Experimental observation of the hybridization of oxygen p states with metal states at the interface in Fe/MgO core/shell self-assembled nanostructures, obtained by vapour-phase deposition, is reported. Synchrotron-based X-ray absorption spectroscopy techniques were used to directly probe the Fe orbital character at the interfacial region. O K edge features suggest the formation of metal-induced states within the band gap of MgO. Thermogravimetric analysis was also used to track interfacial phase changes after different annealing processes. These data demonstrate the relevant role of annealing protocols in controlling the barrier interface, which determine the actual characteristics of spin polarized tunnelling conduction processes. [ABSTRACT FROM AUTHOR]

BACKGROUND Over recent decades, there has been increasing global concern over public health impacts related to water pollution with arsenic. With the development of nanotechnology, nanomaterials are being proposed as alternative agents for water treatment. This study focuses on the use of core-shell nanoparticles as secondary receptors able to operate under intense conditions and perform efficient yet environmentally friendly regeneration of conventional adsorbents. RESULTS Hybrid MgO-coated Fe nanoparticles are proposed, optimized to achieve maximum arsenic uptake under a strong alkaline environment, such as the NaOH stream used to regenerate a typical oxy-hydroxide adsorption column. The magnetic response of these nanocomposites enables their recovery and recirculation by means of an external magnetic field. A scalable laboratory continuous flow system was designed as a proof-of-concept to provide maximum efficiency of the recirculating nanoparticles, as well as complete reuse of the alkaline washing solution. A risk assessment scheme was conducted to evaluate the potential environmental impact of nanoparticle residues by testing the toxicity of arsenic-loaded materials in RTgill-W1 cells and their inertization into concrete building blocks. CONCLUSION The presented methodology illustrates a way to incorporate nanoparticles in water technology taking advantage of their surface activity and magnetic separation potential. © 2016 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

We report on a growth study of MgO films deposited on Al2O3(0001) substrates by magnetron sputtering. The films exhibited a preferred rocksalt MgO(111) orientation. Surprisingly, depending on the O2 gas flow ratio, a structure of graphiticlike wurtzite MgO(0001) has been revealed. The observed Mg-O perpendicular bond length reduction is accompanied by an atomically flat surface morphology for the development of MgO(111) films; the transition to the bulk rocksalt structure occurs in the 3-6 nm coverage range. Previously, relaxation of the electrostatic instability of MgO(111) films accompanied by an in-plane lattice increase has been suggested theoretically [Phys. Rev. Lett. 98, 205701 (2007)]. Here, relying on ab initio calculations, we infer that Mg vacancies facilitate the lattice match with the substrate. This mechanism suggests methods to engineer oxide heterostructures. [ABSTRACT FROM AUTHOR]

The prediction and experimental demonstration of a very hirge magnetoresistance in Fe/MgO/Fe tunnel junctions have led to intense study of related systems in the last decade. In the present paper, we concentrate on the role of interface coordination, Fe thickness, and magnetization in the MgO/Fe/MgO mirror. By first-principles analysis, it is shown that the iron magnetic moment can rise up to 4 &MGR;B, accounting for observed deviation of the Fe atoms in the vicinity of MgO interfaces. The origin is attributed to site preference predicted by our calculations, namely, that, unlike the case of Fe atoms in the monolayer range sitting just above the oxygen atoms of the MgO(001 ) substrate, the charge transfer induced by the O p-d Fe interaction leads to a structural distortion that stabilizes the Mg at the very first deposition stages of the capping layer, facing Fe sites [ABSTRACT FROM AUTHOR]