The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform

D Marrerolopez - One of the best experts on this subject based on the ideXlab platform.

  • Chemical stability and Compatibility of double perovskite anode materials for sofcs
    Solid State Ionics, 2013
    Co-Authors: Dos L Santosgomez, Jose M Porrasvazquez, Enrique R Losilla, Laura Leonreina, D Marrerolopez
    Abstract:

    Abstract Double perovskites with composition Sr 2 BMoO 6 − δ (B = Mg, Ni and Co) and Sr 2 Fe 1.5 Mo 0.5 O 6 − δ have been proposed as potential anode material for direct hydrocarbon oxidation in solid oxide fuel cells (SOFCs). However, the phase stability under different atmospheres (H 2 and CO 2 ) and the Chemical Compatibility with different electrolytes of most of these materials have not been previously studied. The Chemical Compatibility studies carried out by X-ray powder diffraction (XRPD) revealed high reactivity between these electrodes and zirconia based electrolytes, Zr 0.84 Y 0.16 O 2 − δ , at temperatures as low as 800 °C with the formation of SrMoO 4 and SrZrO 3 as main reaction products; however, lower Chemical reactivity was found with Ce 0.8 Gd 0.2 O 2 − δ . Sr 2 CoMoO 6 − δ and Sr 2 NiMoO 6 − δ phases resulted to be unstable under reducing atmosphere above 800 °C, decomposing partially into Sr 3 MoO 6 and Co/Ni metals respectively. These two materials also exhibited low resistance to carbonation in the intermediate temperature range 600–800 °C. Nevertheless, Sr 2 Fe 1.5 Mo 0.5 O 6 − δ is stable under H 2 and pure CO 2 atmospheres. Furthermore, area specific resistances of these anode materials in symmetrical cells were determined in order to compare their electroChemical efficiency.

  • single step reactive sintering and Chemical Compatibility between la9sr1si6o26 5 and selected cathode materials
    Ceramics International, 2012
    Co-Authors: Jose M Porrasvazquez, Lucia Dos Santosgomez, Isabel Santacruz, Miguel A G Aranda, D Marrerolopez, Enrique R Losilla
    Abstract:

    Abstract Apatite-type silicates are considered as promising electrolytes for solid oxide fuel cells (SOFC). However more studies on the Chemical Compatibility of these materials with common SOFC electrodes are required. Here, we report the synthesis of single phase La 9 Sr 1 Si 6 O 26.5 composition by reactive sintering at 1650 °C for 10 h. Fully dense pellets showed very high oxide-anion conductivity, 25 mS cm −1 at 700 °C. Furthermore, the Chemical Compatibility of La 9 Sr 1 Si 6 O 26.5 with some selected cathode materials has also been investigated. The lowest reaction temperatures were determined to be 1100 °C, 1000 °C and 900 °C for La 0.8 Sr 0.2 MnO 3− δ , La 2 Ni 0.8 Cu 0.2 O 4 and La 0.6 Sr 0.4 Co 0.8 Fe 0.2 O 3 , respectively. The segregation of minor amounts of SiO 2 seems to be a key limiting factor that must be overcome. Finally, these cathode materials were deposited over dense oxy-apatite pellets and the area specific resistances in symmetrical cells were determined. These values, at 700 °C, were 14.4 and 2.6 Ω cm 2 for La 0.8 Sr 0.2 MnO 3− δ and La 0.6 Sr 0.4 Co 0.8 Fe 0.2 O 3− δ , respectively. Furthermore, the area specific resistances are notably improved 0.6 Ω cm 2 when a 50 wt.% composite of La 0.6 Sr 0.4 Co 0.8 Fe 0.2 O 3− δ and Ce 0.8 Gd 0.2 O 1.9 is used.

  • redox behaviour Chemical Compatibility and electroChemical performance of sr2mgmoo6 δ as sofc anode
    Solid State Ionics, 2010
    Co-Authors: Miguel A G Aranda, D Marrerolopez, J Penamartinez, J C Ruizmorales, P Nunez, M Gabas, J R Ramosbarrado
    Abstract:

    Abstract The double perovskite Sr 2 MgMoO 6 −  δ (SMM) has been proposed as a potential anode material for direct hydrocarbon oxidation in solid oxide fuel cells (SOFCs). The oxygen nonstoichiometry and electrical conductivity dependence of Sr 2 MgMoO 6 −  δ have been determined as a function of the oxygen partial pressure by coulometric titration and impedance spectroscopy techniques. The Chemical Compatibility of Sr 2 MgMoO 6 −  δ with most of the typical electrolytes commonly used in SOFCs i.e. La 0.8 Sr 0.2 Ga 0.8 Mg 0.2 O 3 −  δ (LSGM), Ce 0.8 Gd 0.2 O 2 −  δ (CGO) and Zr 0.84 Y 0.16 O 2 −  δ (YSZ), was investigated. Reactivity between SMM and all these electrolytes has been found above 1000 °C, although the reaction is most severe with ZrO 2 -based electrolytes. Area-specific polarisation resistance of the SMM/LSGM/SMM symmetrical cells indicates that the polarisation resistance increases with the firing temperature of the electrodes due to Chemical interaction between LSGM and SMM layers. A CGO buffer layer between the anode and electrolyte was also used to prevent an excessive interdiffusion of ionic species between these components, resulting in better performance. Power densities of 330 and 270 mW cm − 2 were reached at 800 °C for SMM/CGO/LSGM/LSCF and SMM/LSGM/LSCF electrolyte-supported cells, respectively; with 600-μm-thick LSGM electrolyte, using humidified H 2 as fuel and air as oxidant. XPS and XRPD studies on SMM powders annealed in air and diluted CH 4 atmospheres showed that the surface of SMM powders is mainly formed by SrMoO 4 and metal carbonates.

  • stability Chemical Compatibility and electroChemical performance of gdbaco2o5 x layered perovskite as a cathode for intermediate temperature solid oxide fuel cells
    Solid State Ionics, 2008
    Co-Authors: D Marrerolopez, A Tarancon, J Penamartinez, A Morata, J C Ruizmorales, P Nunez
    Abstract:

    Abstract Stability under atmospheres containing CO 2 and Chemical Compatibility of GdBaCo 2 O 5 + x with different oxide-ion conductors (8 mol% Y 2 O 3 -ZrO 2 , La 0.8 Sr 0.2 Ga 0.8 Mg 0.2 O 3-δ and Ce 0.9 Gd 0.1 O 1.95 ) have been studied in order to evaluate its suitability as a cathode material for Solid Oxide Fuel Cells (SOFCs). Thermal evolution of X-ray diffraction patterns of GdBaCo 2 O 5 + x in atmospheres with different contents of carbon dioxide (500 ppm to 100% CO 2 ) was used to determine the stability of this compound, which is susceptible to carbonate due to the presence of Ba. Remarkable stability under air conditions for long periods of time (100 h) at different temperatures of interest (500, 600 and 700 °C) was observed. Chemical Compatibility with different electrolytes was evaluated analysing the evolution with calcination temperature (800–1200 °C) of the X-ray diffraction patterns of intimate mixtures of GdBaCo 2 O 5 + x with each electrolyte. ElectroChemical characterization by means of impedance spectroscopy as a part of optimized symmetrical cells (GdBaCo 2 O 5 + x /electrolyte/GdBaCo 2 O 5 + x ) were carried out yielding excellent performance for La 0.8 Sr 0.2 Ga 0.8 Mg 0.2 O 3-δ and Ce 0.9 Gd 0.1 O 1.95 electrolyte-based cells.

Paula Lopezarce - One of the best experts on this subject based on the ideXlab platform.

  • physico Chemical stone mortar Compatibility of commercial stone repair mortars of historic buildings from paris
    Construction and Building Materials, 2016
    Co-Authors: Paula Lopezarce, M Tagnithammou, Beatriz Menendez, J D Mertz, M Guiavarch, Abdelhak Kaci, Salima Aggoun, A Cousture
    Abstract:

    Abstract The physico-Chemical Compatibility of the most frequently used commercial stone-repair mortars applied to repair surface damage of a common limestone (Euville stone) employed in the basements of historic buildings from Paris was assessed. The characterization of anhydrous raw mortar materials, of stone and mortar samples collected from these buildings and laboratory specimens was carried out. The presence of chlorides and sulfates (gypsum and mixtures of calcium and sodium sulfates) with minor amounts of nitrates in mortar samples collected from the buildings suggest an origin of salts caused by contamination/pollution coming from past restoration products and environmental pollution. The mortar containing quartz, marble aggregates, portlandite and hydraulic components (C3S, C2S and C2AS) with addition of aluminosilicate micro-spherical particles with cementitious properties, and no phyllosilicates, shows a better Chemical Compatibility with the stone. The mechanical properties of this mortar are also closer to those of the limestone. However, some differences in the hydric properties due to their different pore systems and aesthetic features should be improved in further restoration works.

Hemantkumar Naik - One of the best experts on this subject based on the ideXlab platform.

  • Chemical Compatibility testing of geomembranes sorption desorption diffusion permeation and swelling phenomena
    Geotextiles and Geomembranes, 1998
    Co-Authors: Tejraj M Aminabhavi, Hemantkumar Naik
    Abstract:

    Abstract The laboratory test results of 14 organic liquids (widely varying in nature) for high density polyethylene, linear low density polyethylene, very low density polyethylene and polypropylene geomembranes are presented at 25, 50 and 70°C. The partition coefficients have been calculated by monitoring the increase in mass of geomembrane immersed in the fluid of interest from its initial value until the mass of geomembrane becomes constant. From such data, diffusion and permeation coefficients have been calculated using Fick’s equation from the initial linear portions of the sorption curves. Swelling of the geomembranes has also been studied from a measurement of an increase in volume, thickness and diameter. From a temperature dependence of sorption, diffusion and permeation coefficients, the Arrhenius parameters have been calculated.

  • Chemical Compatibility study of geomembranes sorption desorption diffusion and swelling phenomena
    Journal of Hazardous Materials, 1998
    Co-Authors: Tejraj M Aminabhavi, Hemantkumar Naik
    Abstract:

    Sorption/desorption results of n-alkanes into high density polyethylene, linear low density polyethylene, very low density polyethylene and polypropylene geomembranes are presented at 25, 50 and 70°C. Sorption results are obtained by a gravimetric method and diffusion coefficients have been calculated by using Fick's equation from the initial linear portions of the sorption/desorption curves. Swelling of the geomembranes was studied from a measurement of the increase in volume, thickness and diameter. From a temperature dependence of sorption and diffusion coefficients, the Arrhenius parameters have been calculated. Liquid concentration profiles have been computed using Fick's equation for the appropriate initial and boundary conditions. The results of this study may have relevance in selecting the suitable geomembrane for a specific application in hazardous waste Chemical ponds and other similar situations.

Liang Fang - One of the best experts on this subject based on the ideXlab platform.

  • naca4v5o17 a low firing microwave dielectric ceramic with low permittivity and Chemical Compatibility with silver for ltcc applications
    Journal of The European Ceramic Society, 2020
    Co-Authors: Changzhi Yin, Guangjie Yang, Liang Fang, Yonghai Yuan, Longlong Shu, Jibran Khaliq
    Abstract:

    Abstract Phase formation, crystal structure and dielectric properties of NaCa4V5O17 ceramics fabricated via a solid state reaction route at relatively low temperatures (780–860 °C) were investigated. NaCa4V5O17 crystallizes in a triclinic structure. Dielectric properties were measured based on the Hakki-Coleman post resonator method at microwave frequency. Specially, a specimen sintered at 840 °C demonstrated balanced dielectric properties with a permittivity er = 9.72, a quality factor Q×f = 51,000 GHz, and a temperature coefficient of resonance frequency τf = −84 ppm/°C. NaCa4V5O17 ceramics showed excellent Chemical Compatibility with Ag metal electrodes. Besides, the thermal stability of resonance frequency was effectively adjusted through formation of composite ceramics between NaCa4V5O17 and TiO2 and a near-zero τf ˜ 1.3 ppm/°C accompanied with er = 14.9 and Q×f = 19,600 GHz was achieved when 50% mol TiO2 was added. All the merits render NaCa4V5O17 a potential candidate for multilayer electronic devices.

  • two novel ultralow temperature firing microwave dielectric ceramics limvo6 m mo w and their Chemical Compatibility with metal electrodes
    Journal of The European Ceramic Society, 2017
    Co-Authors: Huaicheng Xiang, Ying Tang, Liang Fang
    Abstract:

    Abstract Low temperature cofired ceramics technology (LTCC) has been widely studied and used in wireless communication because of their outstanding capability for device miniaturization and integration. However, many commercial microwave dielectric materials have high sintering temperatures that pose challenge for cofiring with inner electrodes. Herein, two brannerite vanadate LiMVO 6 (M = Mo, W) ceramics with intrinsically low sintering temperatures were prepared. Dense and stable LiMVO 6 (M = Mo, W) ceramics could obtained at 640 °C for LiMoVO 6 and 700 °C for LiWVO 6 . Favorable microwave dielectric properties were also obtained with e r =  13.3, Q × f  = 12,460 GHz, and τ f  = +101.0 ppm/°C for LiMoVO 6 and e r =  11.5, Q × f  = 13,260 GHz, and τ f  = +163.8 ppm/°C for LiWVO 6 . Moreover, the relationship between crystal structure and microwave dielectric properties was studied by means of packing fraction, bond valence, and octahedral distortion. Their Chemical Compatibility with the metal electrodes were confirmed.

  • two novel low firing na2amg2v3o12 a nd sm ceramics and their Chemical Compatibility with silver
    Ceramics International, 2017
    Co-Authors: Liang Fang, Huaicheng Xiang, Ying Tang, Xuewen Jiang, Xianran Xing
    Abstract:

    Two novel microwave dielectric ceramics Na2AMg2V3O12 (A=Nd, Sm) with cubic garnet structure were obtained by the conventional solid-state reaction method. Both ceramics could be well densified at 850 °C for 4 h. The Na2NdMg2V3O12 (NNMV) ceramic exhibited good microwave dielectric properties with a permittivity er of 12, a quality factor Qu×f value of 26,544 GHz (at 10 GHz) and a negative temperature coefficient of resonant frequency τf value of −63 ppm/°C and the Na2SmMg2V3O12 (NSMV) ceramic had a er of 12.1, a Qu×f value of 36,207 GHz (at 9.8 GHz) and a negative τf value of −69 ppm/°C. The large negative τf values could be compensated by forming solid solution with LiCa2Mg2V3O12 and 0.7Na2AMg2V3O12 (A=Nd, Sm)–0.3LiCa2Mg2V3O12 sintered at 880 °C for 4 h exhibited a near zero τf ~−4.5 ppm/°C and 5.5 ppm/°C, respectively. Both ceramics were found to be Chemically compatible with Ag electrode at 850 °C for 4 h. These merits make them promising candidates for low-temperature co-fired ceramic technology (LTCC).

  • a novel ultra low temperature cofired na2bizn2v3o12 ceramic and its Chemical Compatibility with metal electrodes
    Journal of Materials Science: Materials in Electronics, 2017
    Co-Authors: Huaicheng Xiang, Liang Fang, Ying Tang, Harshit Porwal
    Abstract:

    Na2BiZn2V3O12 ceramic was investigated as a promising microwave dielectric material for the ultra-low-temperature co-fired ceramic (ULTCC) technology. Dense Na2BiZn2V3O12 ceramic was prepared using the conventional solid-state method from 560 to 640 °C. X-ray diffraction data show that Na2BiZn2V3O12 ceramic crystallized into a cubic garnet structure with a space group Ia-3d. The sample sintered at 600 °C for 4 h has the highest relative density of 96.3 % and exhibits the optimum microwave properties with a relative permittivity of 22.3, a quality factor of 19,960 GHz (at 8.7 GHz), and a temperature coefficient of resonance frequency of +15.5 ppm/°C. The Na2BiZn2V3O12 ceramic was found to be Chemically compatible with highly conductive aluminum and sliver electrode. These results confirm that Na2BiZn2V3O12 ceramic can be a promising candidate for the ULTCC technology.

  • a novel low firing microwave dielectric ceramic namg4v3o12 and its Chemical Compatibility with silver electrode
    Ceramics International, 2015
    Co-Authors: Xuewen Jiang, Liang Fang, Huaicheng Xiang, Huanhuan Guo
    Abstract:

    Abstract A tetragonal vanadate ceramic NaMg 4 V 3 O 12 was fabricated and its microwave dielectric properties were investigated. NaMg 4 V 3 O 12 ceramics could be well densified at 690 °C and exhibited favorable microwave dielectric properties with a low relative permittivity ( e r ) ~12.5, a high quality factor ( Q u ×f ) value ~35,900 GHz ( f =10.5 GHz) and a negative temperature coefficient of resonant frequency ( τ f )~−58.1 ppm/°C. NaMg 4 V 3 O 12 ceramic was found to be Chemically compatible with Ag when sintered at 690 °C for 4 h. The large negative τ f value of NaMg 4 V 3 O 12 could be tuned by adding CaTiO 3 , and 0.92NaMg 4 V 3 O 12 –0.08CaTiO 3 ceramic sintered at 730 °C for 4 h exhibited a near zero τ f ~−3.8 ppm/°C with e r ~24.3, Q u ×f ~ 29,200 GHz. The results suggest it a promising ceramic for low temperature co-fired ceramic (LTCC) applications as substrate in microwave integrated circuits.

A Tarancon - One of the best experts on this subject based on the ideXlab platform.

  • stability Chemical Compatibility and electroChemical performance of gdbaco2o5 x layered perovskite as a cathode for intermediate temperature solid oxide fuel cells
    Solid State Ionics, 2008
    Co-Authors: D Marrerolopez, A Tarancon, J Penamartinez, A Morata, J C Ruizmorales, P Nunez
    Abstract:

    Abstract Stability under atmospheres containing CO 2 and Chemical Compatibility of GdBaCo 2 O 5 + x with different oxide-ion conductors (8 mol% Y 2 O 3 -ZrO 2 , La 0.8 Sr 0.2 Ga 0.8 Mg 0.2 O 3-δ and Ce 0.9 Gd 0.1 O 1.95 ) have been studied in order to evaluate its suitability as a cathode material for Solid Oxide Fuel Cells (SOFCs). Thermal evolution of X-ray diffraction patterns of GdBaCo 2 O 5 + x in atmospheres with different contents of carbon dioxide (500 ppm to 100% CO 2 ) was used to determine the stability of this compound, which is susceptible to carbonate due to the presence of Ba. Remarkable stability under air conditions for long periods of time (100 h) at different temperatures of interest (500, 600 and 700 °C) was observed. Chemical Compatibility with different electrolytes was evaluated analysing the evolution with calcination temperature (800–1200 °C) of the X-ray diffraction patterns of intimate mixtures of GdBaCo 2 O 5 + x with each electrolyte. ElectroChemical characterization by means of impedance spectroscopy as a part of optimized symmetrical cells (GdBaCo 2 O 5 + x /electrolyte/GdBaCo 2 O 5 + x ) were carried out yielding excellent performance for La 0.8 Sr 0.2 Ga 0.8 Mg 0.2 O 3-δ and Ce 0.9 Gd 0.1 O 1.95 electrolyte-based cells.