Improvements in the processing of Yb:YAG ceramic materials

Laser ceramics can attain a significant role in the frame of the generation of high peak power, high energy laser pulses at high repetition rate, applications where fiber lasers or single crystals undergo fundamental or technological limitations. A ceramic material in order to be used as a laser amplifier, needs to fulfil strict requirements in terms of properties, in particular microstructure, purity level, porosity. The important role played by the production process on the transparency of ceramic materials has been explained elsewhere. The current study focuses on the optimization of the powder processing. An innovative Spray Drying process of solvent-based suspensions has been adopted for the preparation of ready-to-press powders for the reactive sintering of Yb:YAG materials. The influence of the experimental conditions on the morphology of the granulated powders and eventually on the microstructure evolution during sintering and the transparency, is describe

Experimental features affecting the transparency of YAG materials

The important role played by the processing on the transparency of ceramic materials is often underestimated. In the literature a high level of transparency has been reported by many authors that for years focused their research on the development of polycrystalline YAG for laser applications,but the description of the experimental process is seldom thoroughly described. A detailed description of the powder treatment and shaping and of other important information that are necessary to reproduce the described results, is often missing. In order to be transparent a ceramic material must exhibit a very low concentration of defects such as secondary or grain boundary phases and residual pores. In order to fulfill this requirement specific experimental conditions must be combined together. Powders need to be nanometric or at least sub-micrometric and extremely pure. On the other hand, nanometric powders aggregate easily and the poor packing that may derived can lead to residual porosity. In addition, very fine powders are difficult to handle and tend to absorb water on the surface. Finally, the powder manipulation (weighting operations, solvent removal, spray drying, shaping, etc), easily introduces impurities. In case of transparent materials all these features must be controlled because they lead to the formation of defects that works as light scattering sources thus decreasing the transparency. This work describes the results obtained with YAG based ceramics under different experimental conditions of powder treatment and shaping. Commercial powders are used for the reactive sintering in a clean atmosphere and under high vacuum of YAG materials doped with Nd, Yb or Er. These dopants have been selected as the more appropriate for high power lasers. The powder treatment (ball milling duration and speed, suspension concentration, solvent/powder ratio, type and amount of dispersant) the solvent removal technique (spray drying conditions, rotavapor temperature, etc.) are described in detail as well as the conditions adopted during shaping. The influence of the powder process on the powder packing during shaping by pressing is also reported. Finally, the influence of the pre-sintering and sintering cycles is also described

Current status of the research on transparent YAG ceramics as laser hosts from an Italian network

This work describes the results obtained using two different processing systems for the production of YAG based ceramics. One involves the use of commercially available oxide powders (Yb2O3, Y2O3, Al2O3) The other involves the use of Yb-doped Y2O3 (Yb, 9.8%) powders obtained by microwave assisted co-precipitation from salts solution and a commercial alumina (Al2O3). Both systems are processed by wet mechanical mixing of starting oxides and reactive sintering of the obtained mixtur

Electropolymerized Polythiophene Layer Extracted from the Interface Between Two Immiscible Electrolyte Solutions: Current-Time Ananlysis

Polythiophene was formed by electropolymerization at the interface between two immiscible electrolyte solutions, using terthiophene as the starting monomer in 1,2-dichloroethane. The water phase contained a redox couple to allow removal of electrons through the interface. For the first time, a layer of polythiophene was produced which was strong enough to extract. The mechanism of electropolymerization was found to be similar to that in the electrodeposition of polythiophene on metals: progressive nucleation and 2D growth precedes 3D growth, ascribed to precipitation of oligomers from solution. The polymer extracted was found to be partially oxidized (irreversibly doped) to a conductive state, and stable in air.JRC.H.8-Renewable energie

Device for stabilizing wine and other vegetable beverages and the related stabilizing method

The invention refers to a continuous flow device for the removal of proteins, metals and other agents of instability of wine and vegetable beverages. The system is constitued by a tube containing inert support material, functionalized to increase its adsorption selectivity. The proposed system, working in continuous flow, determines a substantial reduction in treatment times, in waste production and ensure removing the causes of protein instability and oxidation in wine. Furthermore, the adsorbent material can be regenerated, guaranteeing more successive uses

Nuovo dispositivo per la stabilizzazione in flusso continuo dei vini bianchi

In questo lavoro vengono presentati i risultati preliminari del progetto “Steady Wine”. Vini bianchi proteicamente instabili sono stati stabilizzati con impiego di materiali ceramici in un sistema a flusso. Il dispositivo filtrante ha dimostrato selettività nella rimozione delle proteine e una efficace prevenzione della instabilità proteica, senza influire sui parametri chimici del vino

Dispositivo per la stabilizzazione del vino ed altre bevande vegetali e relativo procedimento di stabilizzazione

L\u2019invenzione si riferisce ad un dispositivo a flusso continuo per la rimozione di proteine, metalli e altri agenti di instabilit\ue0 del vino e bevande vegetali. Il sistema \ue8 costituito da un tubo contenente materiale inerte di supporto, funzionalizzato per aumentarne la selettivit\ue0 di adsorbimento. Il sistema proposto, lavorando in flusso continuo, determina una riduzione sostanziale dei tempi di trattamento, della produzione degli scarti e la contemporanea possibilit\ue0 di rimuovere le cause di instabilit\ue0 proteica e delle ossidazioni nel vino. Inoltre, il materiale adsorbente utilizzato pu\uf2 essere rigenerato garantendo pi\uf9 utilizzi successivi

Sustainability of Organic Dye-Sensitized Solar Cells: The Role of Chemical Synthesis

The synthesis of a novel and efficient π-extended D-A-π-A organic sensitizer (<b>G3</b>, η = 8.64%) for dye-sensitized solar cells has been accomplished by applying the green chemistry pillars, aiming at overriding traditional routes involving organometallic intermediates with innovative synthetic strategies for reducing the waste burden and dye production costs. It has been demonstrated that the obtainment of a complex target sensitizer can be exclusively pursued via direct arylation reactions. Green metrics comparison with those of a traditional synthetic pathway clearly indicates that the new approach has a lower environmental impact in terms of chemical procedures and generated wastes, stressing the importance of the synergy between the molecular design and the synthetic plan in the framework of environmentally friendly routes to back up sustainable development of third-generation photovoltaics. Additionally, the stability of the <b>G3</b>-based photovoltaic devices was also investigated in aging tests on large area devices, evidencing the excellent potentialities of the proposed structure for all practical applications involving inorganic semiconductor/organic dye interfaces