Evaluation of a sol–gel process for the synthesis of La1−xSrxMnO3+δ cathodic multilayers for solid oxide fuel cells

Solid oxide fuel cells (SOFCs) are electrical energy conversion devices with high efficiency and low pollution. In order to increase performances of SOFCs at intermediate temperature (700–800 °C) and to decrease materials cost, an alternative sol–gel synthesis method has been investigated to deposit La1−xSrxMnO3+δ (LSMx) as cathode thin films. Polycrystalline LSMx thin films were prepared by dip-coating using a polymeric solution. Lanthanum, strontium and manganese nitrates were used as raw materials. The viscosity of the solution was adjusted and the solution was deposited on polycrystalline ZrO2–8% Y2O3 ceramics. Prior to experiments, the substrate surface was eroded until a roughness of 20 nm and then cleaned with ethanol and dried. Film thicknesses were adjusted with the number of layers. Porosity and grain size of monolayers or multilayers were evaluated. Typical thickness of monolayer is 250 nm. A key parameter in the multilayer process was the intermediate calcination temperature (400, 700 or 1000 °C) of each further layer deposition. A correlation between this intermediate temperature and morphology, thickness and porosity was found; porosity is ranging from 3 to 40% and thickness can reach 1 micron for multilayers. Concerning electrochemical performances, the best results were obtained for LSM0.4 multilayers with an intermediate calcination temperature (called Ti) of 400 °C

The search campaign to identify and Image the Philae Lander on the surface of comet 67P/Churyumov-Gerasimenko

On the 12th of November 2014, the Rosetta Philae Lander descended to make the first soft touchdown on the surface of a comet – comet 67P/Churyumov- Gerasimenko. That soft touchdown did occur but due to the failure in the firing of its two harpoons, Philae bounced and travelled across the comet making contact with the surface twice more before finally landing in a shaded rocky location somewhere on the southern hemisphere of the comet. The search campaign, led by ESA, involved multiple teams across Europe with a wide range of techniques used in support of it. This search campaign would continue through 2015 where a prime candidate on the surface was identified and on into 2016 to end on the 2nd of September 2016 when a definitive and conclusive image was taken of the lander on the surface of the comet, confirming the prime candidate to indeed be Philae

De l'origine de la Rotation Directe de la Terre et des Planetes

SIGLEINIST T 73623 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

Chemoresistor type gas sensor having a multi-storey architecture

International audienceA multi-storey gas sensor is constructed by stacking chemoresistor type gas sensing elements (CH1,CH2) and providing holes through each sensing element, at least in the region where the sensing layer (52) is formed, so that gas can pass from one sensing element to the next, through the sensing layers (52). A rich set of measurements can be obtained, enabling the characterisation/analysis of a gas under test with increased accuracy and/or the tailoring of the measurements to the particular gas-sensing application: notably by selecting appropriate combinations of materials for the sensing layers of the different gas-sensing elements and by varying the operating conditions applicable to the different gas-sensing elements notably by: taking measurements at respective times when different combinations of sensing layers in the stack are activated, at times when given sensing layers are heated to different temperatures or according to different heating profiles, and/or when selected sensing layers are exposed to UV light. Sensor sensitivity and selectivity can be increased by applying UV pulses of controlled duration. For miniaturization, and increased measurement-speed, each sensing element (CH1,CH2) may have a micro-hotplate architecture

Chemoresistor type gas sensor using pulsed ultraviolet light

Également publié en tant que: CN103718031 (A) CN103718031 (B) CN105784787 (A) CN105784787 (B) CN109298028 (A) EP2533037 (A1) EP2533037 (B1) EP2718705 (A1) JP2014519042 (A) JP2018077232 (A) JP6258196 (B2) KR101966682 (B1) KR102028399 (B1) KR20140074269 (A) KR20190035943 (A) US2014105790 (A1) US9194834 (B2) WO2012168444 (A1)International audienceA multi-storey gas sensor is constructed by stacking chemoresistor type gas sensing elements (CH1,CH2) and providing holes through each sensing element, at least in the region where the sensing layer (52) is formed, so that gas can pass from one sensing element to the next, through the sensing layers (52). A rich set of measurements can be obtained, enabling the characterisation/analysis of a gas under test with increased accuracy and/or the tailoring of the measurements to the particular gas-sensing application: notably by selecting appropriate combinations of materials for the sensing layers of the different gas-sensing elements and by varying the operating conditions applicable to the different gas-sensing elements notably by: taking measurements at respective times when different combinations of sensing layers in the stack are activated, at times when given sensing layers are heated to different temperatures or according to different heating profiles, and/or when selected sensing layers are exposed to UV light. Sensor sensitivity and selectivity can be increased by applying UV pulses of controlled duration. For miniaturization, and increased measurement-speed, each sensing element (CH1,CH2) may have a micro-hotplate architecture

Progress on lanthanide sesquioxide phase transition

The present work aims to bring an original approach to the understanding of the polymorphic transition of RE2O3 from the low-temperature polymorph to the higher-temperature polymorph: from the cubic C to the hexagonal A form or from the monoclinic C to the monoclinic B form, for which the transition temperatures depend intimately on the rare earth element. The view proposed here, focusing on the lanthanide sesquioxide series, from Nd2O3 to Dy2O3, includes crystallographic and energetic considerations, using both bulk and surface energy calculations. After a complete description of the polymorphic filiations based on A, B and C unit cells described on simplified RE cation stacking schemes, it will be shown that the growth of the crystallite size as a function of temperature explains the existence of such transitions for these sesquioxides

Investigation of the first-order phase transition in the Co(1-x)Mg(x)MoO(4) solid solution and discussion of the associated thermochromic behavior

A series of compounds of Co(1-x)Mg(x)MoO(4) compositions has been prepared by a conventional ceramic route. The members of the whole solid solution exhibit a reversible first-order phase transition which was probed by using thermal expansion and low-temperature reflectivity techniques. Whereas the α → β transition temperature evolves linearly on warming from 435 to 200 °C with x going from 0 to 0.9, the β → α transition temperature variation falls down on cooling from -40 °C to -140 °C going from CoMoO(4) to Co(0.1)Mg(0.9)MoO(4) with an asymptotic evolution. The phase transition temperatures have been explained on the basis of a crystal polarization effect under substitution of Mg for Co. Thus, from an applicative point of view, new thermochromic pigments with tunable transition temperatures are here proposed

Optical contrast and cycling of bistable luminescence properties in Rb2KIn(1-x)CexF6 compounds

Irradiation cycling was performed to evaluate the ageing of the redox process observed on cerium-doped Rb2KInF6 compounds. An on-off switch of monovalent indium luminescence is observed for the lowest cerium doped material, whereas a nice colourimetric contrast between a bluish-green and orange emission is generated for the material with the highest cerium content. Photoluminescent properties combined with X-ray diffraction, chemical analysis and magnetism measurements allowed an accurate characterization of the system. A complete explanation of the optical behaviour is therefore proposed. Finally, printing tests were performed to illustrate the good functionality of the prepared materials for UV sensitivity.Matériaux avancés pour capteurs optiques.Initiative d'excellence de l'Université de Bordeau

Étude géologique : nature et provenance des blocs de pierre de la cargaison

Bromblet Philippe, Berthonneau Jérémie, Leroux Lise, Gaudon Pierre, Mercurio Vincent. Étude géologique : nature et provenance des blocs de pierre de la cargaison. In: Archaeonautica, 18, 2014. Arles-Rhône 3.Un chaland gallo-romain du Ier siècle après Jésus-Christ, sous la direction de Sabrina Marlier. pp. 248-253