77 research outputs found
Conductivity of commercial zirconia electrolytes. II. n-Type conductivity of 15 m/o CSZ and 7.5 m/o MSZ at oxygen pressures of solid nickel-solid nickel oxide mixture
No full textThe n-type cond. of the com. 7.5 m/o MgO-stabilized ZrO2 and 15 m/o CaO-stabilized ZrO2 electrolytes was measured at O pressures of the Ni(s)-NiO(s) mixt. at 1073-1423 K by using the blocking electrode technique. The exptl. values of the activation energies were, resp., 1.58 and 1.38 eV for CaO-stabilized and MgO-stabilized ZrO2. The O ion transport no. was also measured as function of temp. and its value at 1273 K was 91%. The significance of the activation energy and PO2 dependence of the partial cond. in the particular exptl. conditions was emphasized
Conductivity of commercial zirconia electrolytes. I. Ionic and n-type conductivities of 15 m/o CSZ at oxygen pressures of solid chromium-solid chromium oxide mixture
No full textThe total and n-type conductivities of com. 15 m/o CaO-stabilized ZrO2 electrolyte were measured. The ionic and n-cond. activation energies are reported at 1195-1917 K as is the n-type cond. dependence on the equil. O partial pressure of the Cr(s)-Cr2O3(s) mixt. electrodes. Values of conduction were detd. and a chronoamperometric technique to measure it is reported. The physicochem. behavior of the Cr(s)-Cr2O3(s) mixt. deriving from certain anomalies obsd. in the cond. trends at the highest temp. values is considered
Thermodynamics of intermetallics through emf measurements under effusion conditions
No full textA general treatment is performed for a complete description of the thermodynamics of galvanic cells PtMe′′, Me′′zF jCaF2s.c./MehMe′k, Me lMe′m,MexFyPt type working under effusion conditions where the vaporization of Me′′ is considered. The treatment has been applied to three Me2Ni17Ni ss systems with Me ≡ Eu, Tb, Ho and Me hMe′k is the solid solution, Niss, produced by the eutectic reaction L ↔ Me2Ni 17s+Niss. From the emf vs T experimental data, ΔfH298θ and Δ fST̄θ have been calculated. The ΔfH298θ values for Tb 2Ni17(s) and Ho2Ni17(s) are, respectively, -16.76±0.06 and -18.8±0.1 kJ/mol atoms. In the same order, the ΔfST̄θ values are -1.27±0.06 and -1.81±0.09 JK-1/ mol atoms, respectively, at T = 1023 and 1085 K. For Eu2Ni17(s), ΔfHT̄θ and Δ fST̄θ are, respectively, -48±4 kJ /mol atoms and 2.0±0.2 JK-1/mol atoms, both the values at T = 910 K. The latter results should be considered unexpected and the reason for this is extensively discussed. © 2003 Elsevier Ltd. All rights reserved
Non-stoichiometric molybdenum oxides as cathodes for lithium cells: Part I. Primary batteries
No full textSome non-stoichiometric Mo oxides have been tested as cathodes for primary Li cells. Their performance has been evaluated as a function of current density, electrolyte, temperature, cathode porosity and formulation. Specific capacities exceeding 0.4·Ah g−1 could be reached at low rates. As found with MoO3, these oxides give rise to the formation of ternary phases of the type LimyMomO3m−1. Li+ insertion in the lattices allows structure retention for Li/Mo ratios lower than 0.7–0.8, whereas higher Li+ contents result in the appearance of new phases
E-mail on the move: Categorization, filtering, and alerting on mobile devices with the ifMail prototype
No full textWe propose an integrated approach to email categorization, filtering, and alerting on mobile devices. After a general introduction to the problem, we present the ifMail prototype, capable of: categorize incoming email messages into pre-defined categories; filter and rank the categorized messages according to their importance; and alert the user on mobile devices when important messages are waiting to be read. The second part of the paper describes an extended evaluation of the ifMail prototype, whose results show the high effectiveness levels reached by the system. © Springer-Verlag Berlin Heidelberg 2004
TRANSPORT PROCESSES AT HIGH-TEMPERATURES RELATED TO OXYGEN ACTIVITY AT YSZ SURFACE
No full textIn a coupled system of O concn. cells with yttria-stabilized zirconia (YSZ) as electrolyte, the behavior vs. time of their emf. is given when the common atm. is initially made up of Ar with an O partial pressure of 1 × 10-14 Pa at 1118 K. A break-point characterizes all the curves, but it occurs at different times, depending on the exptl. setup, but at the same emf. value. Adsorption of O on a porous Pt electrode is assumed to occur, and the free energy change of desorption was 234 kJ/mol
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