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Titulo: Mechanochemically Synthesized CuFeSe2 Nanoparticles and Their Properties
Autores: Dutkova, E; Skorvanek, I; Sayagues, MJ; Zorkovska, A; Kovac, J; Balaz, P
Revista: Acta Physica Polonica A, 131 (2017) 1156-1158
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The mechanochemical synthesis of nanocrystalline CuFeSe2 particles prepared by high-energy milling in a planetary mill in an argon atmosphere from copper, iron, and selenium for 60 min is reported for the first time. The CuFeSe2 nanoparticles crystallize in tetragonal structure with mean crystallite size of about 32 +/- 1 nm. High resolution transmission electron microscopy measurements confirmed the presence of agglomerates which are formed by small nanocrystalline domains (5-40 nm). The magnetic data revealed that paramagnetic CuFeSe2 nanoparticles coexist with a small amount of ferromagnetic impurities at room temperature. The magnetic transition towards a weak ferromagnetic or ferrimagnetic behavior occurs in CuFeSe2 at approximately 79 K. The band gap of the CuFeSe2 particles is 0.95 eV which is wider than the band gap in bulk materials (0.16 eV), which could be in many aspects of application more beneficial.

Abril, 2017 | DOI: 10.12693/APhysPolA.131.1156

Titulo: Aperiodic Metal-Dielectric Multilayers as Highly Efficient Sunlight Reflectors
Autores: Alberto Jiménez-Solano; Miguel Anaya; Mauricio E. Calvo; Mercedes Alcon-Camas; Carlos Alcañiz; Elena Guillén; Noelia Martínez; Manuel Gallas; Thomas Preussner; Ramón Escobar-Galindo; Hernán Míguez
Revista: Advanced Optical Materials, 5 (2017) 1600833
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The optimum reflection of the solar spectrum at well-defined incident directions as well as its durability in time are, both, fundamental requirements of the optics of thermosolar and photovoltaic energy conversion systems. The stringent high performance needed for these applications implies that, almost exclusively, second face mirrors based on silver are employed for this purpose. Herein, the possibility to develop solar mirrors using other metals, such as copper and aluminum, is theoretically and experimentally analyzed. It is found that reflectors based on these inexpensive metals are capable of reflecting the full solar spectrum with efficiencies comparable to that of silver-based reflectors. The designs herein proposed are based on aperiodic metal-dielectric multilayers whose optimized configuration is chosen employing a code based on a genetic algorithm that allows selecting the best one among 108 tested reflectors. The use of metals with wider spectral absorption bands is compensated by the use of multilayered designs in which metal absorption is almost suppressed, as the analysis of the electric field intensity distribution demonstrates. The feasibility of the proposed mirrors is demonstrated by their actual fabrication by large area deposition techniques amenable for mass production.

Marzo, 2017 | DOI: 10.1002/adom.201600833

Titulo: Strong Quantum Confinement and Fast Photoemission Activation in CH3NH3PbI3 Perovskite Nanocrystals Grown within Periodically Mesostructured Films
Autores: Miguel Anaya; Andrea Rubino; Teresa Cristina Rojas; Juan Francisco Galisteo-López; Mauricio Ernesto Calvo; Hernán Míguez
Revista: Advanced Optical Materials
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In this Communication, a synthetic route is demonstrated to obtain stabilized MAPbI3 nanocrystals embedded in thin metal oxide films that display well-defined and adjustable quantum confinement effects over a wide range of 0.34 eV. Mesostructured TiO2 and SiO2 films displaying an ordered 3D pore network are prepared by evaporation-induced self-assembly of a series of organic supramolecular templates in the presence of metal oxide precursors. The pores in the inorganic films obtained after thermal annealing are then used as nanoreactors to synthesize MAPbI3crystallites with narrow size distribution and average radius comprised between 1 and 4 nm, depending on the template of choice. Both the static and dynamic photoemission properties of the ensemble display features distinctive of the regime of strong quantum confinement. Photoemission maps demonstrate that the spectral and intensity properties of the luminescence extracted from the perovskite quantum dot loaded films are homogeneous over squared centimeters areas. At variance with their bulk counterparts, constant emission intensity is reached in time scales at least four orders of magnitude shorter.

Marzo, 2017 | DOI: 10.1002/adom.201601087

Titulo: Diverse Applications of Nanomedicine
Autores: Pelaz, Beatriz; Alexiou, Christoph; Alvarez -Puebla, Ramon A.; Alves, Frauke; Andrews, Anne M.; Ashraf, Sumaira; Balogh, Lajos P.; Ballerini, Laura; Bestetti, Alessandra; Brendel, Cornelia; Bosi, Susanna; Carril, Monica; Chan, Warren C. W.; Chen, Chunying
Revista: ACS Nano, 11 (2017) 2312-2381
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The design and use of materials in the nanoscale size range for addressing medical and health-related issues continues to receive increasing interest. Research in nanomedicine spans a multitude of areas, including drug delivery, vaccine development, antibacterial, diagnosis and imaging tools, wearable devices, implants, high-throughput screening platforms, etc. using biological, nonbiological, biomimetic, or hybrid materials. Many of these developments are starting to be translated into viable clinical products. Here, we provide an overview of recent developments in nanomedicine and highlight the current challenges and upcoming opportunities for the field and translation to the clinic.

Marzo, 2017 | DOI: 10.1021/acsnano.6b06040

Titulo: Multicolored Emission and Lasing in DCM-Adamantane Plasma Nanocomposite Optical Films
Autores: Alcaire, M; Cerdan, L; Zamarro, FL; Aparicio, FJ; Gonzalez, JC; Ferrer, FJ; Borras, A; Espinos, JP; Barranco, A
Revista: ACS Applied Materials & Interfaces, 9 (2017) 8948-8959
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We present a low-temperature versatile protocol for the fabrication of plasma nanocomposite thin films to act as tunable emitters and optical gain media. The films are obtained by the remote plasma-assisted deposition of a 4-(dicyano-methylene)-2-methy1-6-(4-dimethylamino-styry1)-4Hpyran (DCM) laser dye alongside adamantane. The experimental parameters that determine the concentration of the dye in the films and their optical properties, including light absorption, the refractive index, and luminescence, are evaluated. Amplified spontaneous emission experiments in the DCM/adamantane nano composite waveguides show the improvement of the copolymerized nano composites' properties compared to films that were deposited with DCM as the sole precursor. Moreover, one-dimensional distributed feed-back laser emission is demonstrated and characterized in some of the nanocomposite films that are studied. These results open new paths for the optimization of the optical and lasing properties of plasma nanocomposite polymers, which can be straightforwardly integrated as active components in optoelectronic devices.

Marzo, 2017 | DOI: 10.1021/acsami.7b01534

Titulo: Monitoring the Reaction Mechanism in Model Biogas Reforming by InSitu Transient and Steady-State DRIFTS Measurements
Autores: Bobadilla, LF; Garcilaso, V; Centeno, MA; Odriozola, JA
Revista: Chemsuschem, 10 (2017) 1193-1201
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In this work, the reforming of model biogas was investigated on a Rh/MgAl2O4 catalyst. In situ transient and steady-state diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) measurements were used to gain insight into the reaction mechanism involved in the activation of CH4 and CO2. It was found that the reaction proceeds through of an initial pathway in which methane and CO2 are both dissociated on Rh metallic sites and additionally a bifunctional mechanism in which methane is activated on Rh sites and CO2 is activated on the basic sites of the support surface via a formate intermediate by H-assisted CO2 decomposition. Moreover, this plausible mechanism is able to explain why the observed apparent activation energy of CO2 is much lower than that of CH4. Our results suggest that CO2 dissociation facilitates CH4activation, because the oxygen-adsorbed species formed in the decomposition of CO2 are capable of reacting with the CHx species derived from methane decomposition.

Marzo, 2017 | DOI: 10.1002/cssc.201601379

Titulo: Large-Scale Storage of Concentrated Solar Power from Industrial Waste
Autores: Perejon, Antonio; Valverde, Jose Manuel; Miranda-Pizarro, Juan; Sanchez-Jimenez, Pedro E.; Perez-Maqueda, Luis A.
Revista: ACS Sustainable Chemistry & Engineering, 5 (2017) 2265-2272
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Deep penetration of renewable energies into the grid relies on the development of large-scale energy storage technologies using cheap, abundant, and nontoxic materials. Concentrated solar power (CSP) is particularly suitable to massively store thermal energy for dispatchable electricity generation. This is currently accomplished in a few demonstration plants by using molten salts albeit in a not competitive way yet. Process simulation studies indicate that thermochemical energy storage of CSP by means of the calcium looping (CaL) technology would reduce the cost of storage and increase the flexibility of energy supply provided that widely available and cheap CaO precursors with high and stable multicycle activity are used. In this work, we investigate the behavior of calcium rich steel slag at CaL conditions that would expectedly maximize the efficiency of CSP energy storage and power production. When treated with acetic acid, this nontoxic widely abundant waste yields a CaO rich solid with stable conversion near 0.8 over successive carbonation/calcination cycles at these CaL conditions

Marzo, 2017 | DOI: 10.1021/acssuschemeng.6b02576

Titulo: New method for carbon dioxide mineralization based on phosphogypsum and aluminium-rich industrial wastes resulting in valuable carbonated by-products
Autores: Romero-Hermida, I; Santos, A; Perez-Lopez, R; Garcia-Tenorio, R; Esquivias, L; Morales-Florez, V
Revista: Journal of CO2 Utilization, 18 (2017) 15-22
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A new carbon mineralization method was designed based on a sequestration agent synthesised exclusively from industrial wastes. Phosphogypsum waste from the fertiliser industry was dissolved into caustic aqueous waste from the aluminium anodising industry. The resulting precipitate consisted of katoite (Ca3Al2(OH) 12, a Si-free hydrogrossular solid solution end-member of the Al-containing hydrogarnet) and thenardite (Na2SO4); the latter easily removed by rinsing with water. The carbonation performance of this katoite-rich sequestration agent was evaluated using two different methods, by bubbling in aqueous media and by weathering. Both procedures yielded high carbonation efficiencies (80% and 100%, respectively), and resulted in a solid precipitate composed primarily of calcite (CaCO3) and aluminium hydroxide (Al(OH)(3)). Priority attention was given to the transfer of trace elements and radionuclides of the uranium series typically present in the phosphogypsum. Results confirmed that the traces were transferred to resulting final solid carbonate at concentrations similar to those present in the raw phosphogypsum. In conclusion, these carbonated minerals would trap substantial amounts of CO2 and produce final materials with similar civil engineering uses to those proposed for current phosphogypsum wastes. This work offers new methods for jointly managing specific industrial wastes oriented to more sustainable industrial processes and controlling CO2 emissions.

Marzo, 2017 | DOI: 10.1016/j.jcou.2017.01.002

Titulo: Solid lubricant behavior of MoS2 and WSe2-based nanocomposite coatings
Autores: Dominguez-Meister, S; Rojas, TC; Brizuela, M; Sanchez-Lopez, JC
Revista: Science and Tecnology of Advances Materials, 18 (2017) 1
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Tribological coatings made of MoS2 and WSe2 phases and their corresponding combinations with tungsten carbide (WC) were prepared by non-reactive magnetron sputtering of individual targets of similar composition. A comparative tribological analysis of these multiphase coatings was done in both ambient air (30-40% relative humidity, RH) and dry nitrogen (RH<7%) environments using the same tribometer and testing conditions. A nanostructural study using advanced transmission electron microscopy of the initial coatings and examination of the counterfaces after the friction test using different analytical tools helped to elucidate what governs the tribological behavior for each type of environment. This allowed conclusions to be made about the influence of the coating microstructure and composition on the tribological response. The best performance obtained with a WSe x film (specific wear rate of 2 x 10(-8) mm(3) N(-1)m(-1) and a friction coefficient of 0.03-0.05) was compared with that of the well-established MoS2 lubricant material.

Marzo, 2017 | DOI: 10.1080/14686996.2016.1275784

Titulo: Ceramics of Ta-doping stabilized orthorhombic ZrO2 densified by spark plasma sintering and the effect of post-annealing in air
Autores: Sponchia, G; Moshtaghioun, BM; Benedetti, A; Riello, P; Gomez-Garcia, D; Dominguez-Rodriguez, A; Ortiz, AL
Revista: Scripta Materialia, 130 (2017) 128-132
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16 mol% Ta-doped ZrO2 powders were synthesized and densified by spark-plasma sintering (SPS) in vacuum, followed by post-SPS annealing in air, thus obtaining two ultrafine-grained ceramics consisting of Ta-doping stabilized orthorhombic ZrO2. The as-SPSed ceramic is black because it is actually a suboxide essentially with reduced cations and abundant oxygen vacancies, whereas the post-annealed ceramic is white because it is an oxide without vacancies and with only partially reduced cations. Both ceramics are relatively hard and brittle, but the as-SPSed ceramic was slightly more so, attributable to crystallographic and microstructural differences. Implications of interest for the ceramics community are discussed.

Marzo, 2017 | DOI: 10.1016/j.scriptamat.2016.11.021



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