Search results for "Metals"
showing 10 items of 2013 documents
Enhanced bistability by guest inclusion in Fe(ii) spin crossover porous coordination polymers
2012
Inclusion of thiourea guest molecules in the tridimensional spin crossover porous coordination polymers {[Fe(pyrazine)[M(CN)(4)]} (M = Pd, Pt) leads to novel clathrates exhibiting unprecedented large thermal hysteresis loops of ca. 60 K wide centered near room temperature.
[Cu(tn)]3[Cr(CN)6]2·3H2O: A unique two-dimensional Cu-Cr cyano-bridged ferromagnet (tn = 1,3-diaminopropane)
2002
Reaction of the two-coordinate ‘assembling complex-ligand’ [Cu(tn)]2+ with the building block [Cr(CN)6]32 leads to a unique two-dimensional Cu–Cr cyano-bridged ferromagnet with unusual m3- and m4-bridging [Cu(tn)]2+ units. Gomez Garcia, Carlos Jose, Carlos.Gomez@uv.es
Reducing the irreducible: Dispersed metal atoms facilitate reduction of irreducible oxides.
2021
Oxide reducibility is a central concept quantifying the role of the support in catalysis. While reducible oxides are often considered catalytically active, irreducible oxides are seen as inert supports. Enhancing the reducibility of irreducible oxides has, however, emerged as an effective way to increase their catalytic activity while retaining their inherent thermal stability. In this work, we focus on the prospect of using single metal atoms to increase the reducibility of a prototypical irreducible oxide, zirconia. Based on extensive self-consistent DFT+U calculations, we demonstrate that single metal atoms significantly improve and tune the surface reducibility of zirconia. Detailed ana…
Dielectric relaxation and polaronic hopping in Mn-substituted LaSrNiO4 nickelates prepared by mechanical milling method
2016
Abstract The structures, microstructures and dielectric properties of LaSrNi1−xMnxO4 (x = 0, 0.1, 0.2, 0.3 and 0.5) ceramics synthetized by mechanical milling followed by heat treatment were studied. One single tetragonal phase was revealed in all compounds. Structural parameters were obtained by Rietveld refinement. The substitution of Ni ions by Mn produces a variation of the lattice parameters but no phase change is observed. The surface morphology and elemental analysis of these samples were respectively investigated by Scanning Electron Microscopy (SEM) and energy dispersive X-ray technique (EDS). Giant dielectric response was observed in these ceramics, and at least two relaxations we…
Heavy Metals in Mollusc Shells: A Quick Method for their Detection
2015
It is known for a long time that calcified tissues secreted by aquatic or terrestrial invertebrates – such as mollusc shells – have the ability to concentrate large amounts of pollutants, in particular heavy metals. In the present paper, we have found an extremely rapid and easy procedure to qualitatively detect the putative presence of heavy metals in shells, without having to use sophisticated techniques such as Wavelength Dispersive Spectroscopy, atomic adsorption spectroscopy or ICP-MS. Our method rests on the capacity of the silver enhancement chemicals that are traditionally used in immunogold localization experiments to increase the size of heavy metal nanoparticles, whatever the che…
Thermoelectric current and magnetic field interaction influence on the structure of directionally solidified Sn-10 wt.%Pb alloy
2013
International audience; In this experimental work Sn-10 wt.% Pb alloy is directionally solidified in Bridgman setup at various growth velocities (from 0.5 mu m/s to 20 mu m/s) under transverse 0.4 T magnetic field. Temperature gradient of 8 K/mm is maintained perpendicular to the solidification direction during experiments. Liquid phase convection and its influence on the structure and segregation of an alloy, caused by magnetic field and thermoelectric current interaction (thermoelectromagnetic convection or TEMC) is studied experimentally and estimated theoretically in this work. Detailed velocity order of magnitude estimation is carried out. Besides optical microscopy, component distribu…
Synthesis of bulk FeAl nanostructured materials by HVOF spray forming and Spark Plasma Sintering
2006
Abstract This paper examines the efficiency of two consolidation processing techniques: High Velocity Oxy-Fuel (HVOF) spray forming and Spark Plasma Sintering (SPS) to obtain bulk nanostructured materials from an Y 2 O 3 reinforced Fe–40Al (at.%) milled powder. The microstructures of the sintered end-products were characterized by Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) in order to gain new insights in their microstructure formation mechanisms. HVOF spray forming is more effective to retain fine nanograins, in particular within retained unmelted powder particles. The drawbacks of this technique are that it inevitably leads to a high fraction of porosity…
Bonding behavior of Bi-metal-deposits produced by hybrid cold spray additive manufacturing
2022
Abstract Cold spraying (CS) is one of the most recently used additive manufacturing (AM) processes that allow forming large 3D objects efficiently without severe thermal effects. However, due to some limitations of the CSAM process, it is difficult to achieve the desired geometry with high precision. As a potential solution to this issue, CSAM process coupled machining, that is, hybrid addition and subtraction manufacturing, is proposed to achieve desired accuracy and reliable shape. Therefore, it is necessary to assess the mechanical reliability of multilayer deposits deposited by CSAM + machining processes before that. In this work, different bi-deposits were obtained via hybrid CSAM. The…
Vacuum arc deposition of protective layers on glass and polymer substrates
2001
Abstract Vacuum arc deposition allows one to deposit various coatings on insulating and temperature-sensitive substrates (like polymers). An advantage of the vacuum arc deposition technique is the low substrate temperature during the deposition process. A vacuum arc deposition apparatus for the coating of large-area substrates has been developed. Ti, TiN, TiO 2 and diamond-like single and multilayer coatings have been deposited on plastic and glass substrates. The vacuum arc technology permits formation of multilayer colour filters of high uniformity on substrates with dimensions up to 2000×1400 mm 2 . The microstructure, chemical composition and optical properties of the deposited coatings…
Deformation behavior of nanostructured ZnO films on glass
2012
Abstract Nanostructured ZnO films on glass substrate were studied by nanoindentation, scanning electron and atomic force microscopy. The films were obtained by a straightforward mechanoactivated oxidation method. The morphology of the obtained films was grained with a grain size in the range 50–100 nm and the thickness was approximately 2 μm. A detailed deformation behavior of ZnO films, critical parameters and indentation induced plastic deformation mechanisms were determined in correlation to bulk ZnO, Si single crystal and commercial ZnO films. In comparison to a single crystal ZnO, nanostructured films exhibit increased hardness (9 GPa); however, the Young's modulus is decreased (120 GP…