Potentialities of the sol-gel route to develop cathode and electrolyte thick layers Application to SOFC systems

In this work, we report the potential of sol–gel process to prepare cathode and electrolyte thin and thick layers on anodic NiO-YSZ supports which were also made from powders prepared by sol–gel route. YSZ and La2 − xNiO4 + δ, La4Ni3O10 were synthesized as electrolyte and cathode materials for SOFC applications. For electrolyte shaping, yttria stabilized zirconia (YSZ, 8% Y2O3) thick films were cast onto porous NiO-YSZ composite substrates by a dip-coating process using a new suspension formulation. Part of the YSZ precursor colloidal sol was added in the suspension to ensure both homogeneity and adhesion of the electrolyte on the anodic substrate after thermal treatment at 1400 °C for 2 h. By precisely controlling the synthesis parameters, dense and gas-tight layers with thicknesses in the range of 10–20 μm have been obtained. Gas-tightness was confirmed by He permeation measurements. Concerning cathode processing, a duplex microstructured cathode consisting of both La2 − xNiO4 + δ ultra-thin films (few nanometers) and La2 − xNiO4 + δ and/or La4Ni3O10 thick layers (few micrometers) was prepared on YSZ substrates by the dip-coating process, with the thickness being dependent on the nature of the dip-coated solution (polymeric sol or adequate suspension). The derived cathode microstructure, related to the number/thickness of layers and type of architecture, was correlated to the good cell electrochemical performances. Concerning cathode processing, a duplex microstructured cathode consisting of both La2 ? xNiO4 + ? ultra-thin films (few nanometers) and La2 ? xNiO4 + ? and/or La4Ni3O10 thick layers (few micrometers) was prepared on YSZ substrates by the dip-coating process, with the thickness being dependent on the nature of the dip-coated solution (polymeric sol or adequate suspension). The derived cathode microstructure, related to the number/thickness of layers and type of architecture, was correlated to the good cell electrochemical performances

Development of lanthanum nickelate as a cathode for use in intermediate temperature solid oxide fuel cells

The performance of lanthanum nickelate, La2NiO4+δ (LNO), as a cathode in IT-SOFCs with the electrolyte cerium gadolinium oxide, Ce0.9Gd0.1O2−δ (CGO), has been investigated by AC impedance spectroscopy of symmetrical cells. A significant reduction in the area specific resistance (ASR) has been achieved with a layered cathode structure consisting of a thin compact LNO layer between the dense electrolyte and porous electrode. This decrease in ASR is believed to be a result of contact at the electrolyte/cathode boundary enhancing the oxygen ion transfer to the electrolyte. An ASR of 1.0 Ω cm2 at 700 °C was measured in a symmetrical cell with this layered structure, compared to an ASR of 7.4 Ω cm2 in a cell without the compact layer. In addition, further improvements were observed by enhancing the cell current collection and it is anticipated that a symmetrical cell consisting of a layered structure with adequate current collection would lower these ASR values further

Parcours spécifiques : allier réussite et contraintes individuelles

Comprend des références bibliographiquesDepuis plus de douze ans, une structure spéciale et efficace a été mise en place au sein de l’Institut Universitaire de Technologie 1 de Grenoble afin d’accueillir et d’accompagner les nombreux étudiants ayant des contraintes fortes dans le déroulement de leurs études. Celle-ci propose des adaptations pour tous types de contraintes individuelles et repose sur une équipe de correspondants et de tuteurs dans chaque département d’enseignement. Les taux de réussite obtenus sont les mêmes que ceux des étudiants n’ayant pas de contraintes particulières ce qui prouve que la compensation des contraintes est bien effectuée. Cependant, les restrictions budgétaires actuelles risquent de remettre en cause ces adaptations bien qu’elles soient peu onéreuses

Elaboration of metallic compacts with high porosity for mechanical supports of SOFC

The development of third generation Solid Oxide Fuel Cells (SOFC) with metallic mechanical supports presents several advantages over that of ceramic stacks by offering a lower cost and longer lifetime of the stacks. As a consequence, it is necessary to prepare metallic porous compacts that remain stable at the operating temperature of the SOFC (700–800 C) under reductive atmosphere. This paper presents an innovative process to elaborate iron, nickel and cobalt porous compacts. The process is based on the thermal decomposition of metal oxalate precursors with controlled morphology into metallic powders with coralline shape. Uniaxial compaction of such powders (without binder addition to the powders) under low uniaxial pressures (rising from 20 to 100 MPa) gave rise to green compacts with high porosity and good mechanical properties. After annealing at 800 C under H2 atmosphere, the compacts still present interconnected porosity high enough to allow sufficient gas flow to feed a SOFC single cell in hydrogen: the porosity rises from 25 to 50% for iron compacts, from 20 to 50% for cobalt compacts, and is higher than 40% for nickel compacts. Results from physicochemical characterization (XRD, SEM, gas permeation, Hg porosimetry) corroborated the process for SOFC application

An Analysis of the Mortality Risks Associated with Heat and Heat Waves in Ireland, to Assist in Planning for Climate Change

Although extreme temperatures have not been identified as a major cause of mortality in Ireland, climate change calls for an evaluation of the past, present and future health risks associated with heat and heat waves. The health impacts of heat were investigated using mortality and temperature data for the period 1981-2003. Data were aggregated in urban areas (Dublin, Cork, Drogheda, Arklow, Dundalk, Galway, Limerick, Waterford and Wexford) and rural areas. Seven heat waves were identified between 1981 and 2003, corresponding to 254 excess deaths (197 in rural areas, and 57 in urban areas). A major episode was observed in rural areas in 1983: +115 [confidence interval CI 95% 96:137] extra deaths between the 5th and the 23rd July 1983. During summer, a 1°C increase above 15°C in the mean temperature was associated with a 1.5% [CI 95% 0.9:2.1] increase in total mortality in rural areas, and a 1.6% [0.6:2.5] increase in total mortality in urban areas. Risks were modified by the mortality observed in the preceding winter. There are indications that the heat-related risks have been decreasing between the 80s and the 90s. A better geographical resolution of the mortality data is an asset to refine this analysis and to study any relationship between a health topic and an environmental exposure. Despite limits on the data, an increase in temperature was associated with an increase in mortality during summer in Ireland, and past heat waves were associated with a small but observable excess mortality. With the perspective of climate change, and with the ageing of the population, it may be that more severe heat episodes results in a larger mortality burden, as was observed during the July 1983 heat wave. Steps to reduce vulnerability to heat during extreme episodes should be considered

Single quantum dash mode-locked laser as a comb-generator in four-channel 112 Gbit/s WDM transmission

International audienceWe demonstrate 100 km transmission at 28 Gbit/s/channel of 4 DWDM channels using a single quantum-dash mode-locked laser. The amplitude noise of each filtered laser line is improved using limiting amplification in an SOA

Pemberdayaan Masyarakat Pesisir Pulau Untungjawa Dalam Upaya Meningkatkan Kesadaran Hukum Dan Kemandirian Nelayan

Kelurahan Pulau Untung Jawa merupakan salah satu dari enam kelurahan di wilayah kepulauan Seribu atau satu di antara tiga kelurahan di wilayah kecamatan Kepulauan Seribu Selatan. Penduduk Pulau Untung Jawa sebagian besar adalah masyarakat pribumi yang silsilahnya berasal dari Pulau Untung Jawa dan perpindahan masyarakat Pulau Ubi Besar tanggal 13 Februari 1954. Kelurahan Pulau Untung Jawa merupakan kawasan andalan Wisata Pemukiman yang mempunyai peranan penting dalam mewujudkan visi kabupaten yaitu: Sebagai Taman dan Ladang Kehidupan Bahari yang Berkelanjutan Penelitian ini menemukan model pemberdayaan yang tepat bagi masyarakat pesisir pulau UntungJawa dan menganalisis upaya peningkatan kesadaran hukum dan kemandirian nelayan Pulau UntungJawa. Penelitian ini termasuk dalam penelitian deskriptif kualitatif dengan pendekatan sosiologis, atau dalam penelitian hukum biasa disebut normatif terapan/normatif empiris. Model pemberdayaan yang bertujuan membangun kemandirian nelayan pulau UntungJawa dapat dilaksanakan dengan kerjasama dan partisipasi masyarakat. Perlu sinergitas antara peran pemerintah baik aparat kelurahan dan instansi terkait lainnya, LSM yang peduli atau pun Perusahaan, kampus maupun masyarakat nelayan itu sendiri. Terdapat faktor pendukung dan faktor penghambat yang harus diperhatikan dan dicarikan solusinya. Faktor pendukung antara lain sudah terbangun konsep kesadaran dalam melakukan segala macam kegiatan yang sesuai dengan hukum yang ada, potensi wisata dan produksi perikanan, aparat Kelurahan yang cukup aktif dan kesiapan SDM untuk memotivasi diri dan menerima pendampingan serta berbagai pelatihan. Adapun faktor penghambatnya antara lain: terbatasnya modal, faktor alam, sarana prasarana, kurangnya gairah wisata, daya minat beli dan daya minat permainan air, tidak adanya penghasillan rutin, honor pekerja yang kurang dari UMP, SDM, dan kurangnya kesadaran hukum, bantuan hukum dan perlindungan hukum

Up to 425 GHz All Optical Frequency Down‐Conversion Clock Recovery Based on Quantum Dash Fabry‐Perot Mode‐Locked Laser

Postdeadline Session C " OFDM and OTDM "International audienceWe demonstrate that quantum‐dash mode‐locked laser can perform all optical frequency down‐conversion clock recovery up to 425 GHz. We measured 0.3 dB penalty on the optical recovered clock for 170 Gbit/s signal

Modelling of the radiative properties of an opaque porous ceramic layer

Solid Oxide Fuel Cells (SOFCs) operate at temperatures above 1,100 K where radiation effects can be significant. Therefore, an accurate thermal model of an SOFC requires the inclusion of the contribution of thermal radiation. This implies that the thermal radiative properties of the oxide ceramics used in the design of SOFCs must be known. However, little information can be found in the literature concerning their operating temperatures. On the other hand, several types of ceramics with different chemical compositions and microstructures for designing efficient cells are now being tested. This is a situation where the use of a numerical tool making possible the prediction of the thermal radiative properties of SOFC materials, whatever their chemical composition and microstructure are, may be a decisive help. Using this method, first attempts to predict the radiative properties of a lanthanum nickelate porous layer deposited onto an yttria stabilized zirconium substrate can be reported