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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
CERAMIC ELECTROLYTE CELLS IN HIGH-TEMPERATURE OXIDATION OF METALS
No full textResults on the high temp. oxidn. of Ni, as obtained when the metal is the anode of an electrochem. cell with Y2O3-stabilized ZrO2 (YSZ) as the electrolyte, are presented. Three-electrode cyclic voltammetry was used to study oxide growth at the YSZ|Pt paste (Ptp)|(NiO)Ni interface by a cell system where sintered Fe-wustite electrodes act both as ref. and counter electrodes. The anal. of the voltammetric curve was carried out by considering that an O-producing charge transfer occurs at the YSZ/Ptp interface and that the oxide grows under an external elec. field which inhibits the oxidn. kinetics. A method for calcg. the current/voltage curve of the growing oxide is also reported
ROLE OF OXYGEN-SUPPLY IN HIGH-TEMPERATURE GROWTH OF COMPACT OXIDE SCALE
No full textHigh-temp. oxidn. of metals at low-O impinging fluxes and low values of O partial pressure were considered on the basis of the fundamental aspects of oxidn. kinetics. The oxidn. kinetics of Cu to the monovalent oxide was studied under appropriate exptl. conditions using app. consisting of 2 solid-state electrochem. cells, both with Y2O3-stabilized ZrO2 as the solid electrolyte, coupled together. The cells operated as O sensors and O pump, resp., in such a way that O was generated and monitored close to the surface of the oxidizing sample. The results obtained on a Cu foil at 1113 K over the O pressure range 1 × 10-14 (highly purified Ar) to 1500 Pa show a linear growth of the oxide for exposures ≤2000 s. This was tentatively explained by assuming the O supply to the sample surface to be the rate-limiting step, instead of the solid-state diffusion into the growing oxide
NEUTRON AND TRITIUM EVIDENCE IN THE ELECTROLYTIC REDUCTION OF DEUTERIUM ON PALLADIUM ELECTRODES
No full textA Fleischmann and Pons type experiment was carried out for approximately 3 months in a ten-cell electrochemical system. All the cells were connected in series, and electrolysis was performed in galvanostatic mode at a maximum current of 2.5 A, corresponding on the average to 500 mA/cm2. In this experiment, all cathodes were made of palladium, and the anodes were made of platinum. In nine cells out of ten, the cathodes were shaped into parallelepipeds (25 x 5 x 5 mm3) by high-vacuum sintering according to a previously reported procedure. The starting material for all these electrodes was palladium sponge powder. The tenth cathode was made of 32 short 0.5-mm-diam palladium wires, gold welded together at one end. A similar concentration of screw dislocations was produced in each wire. Three different groups of sintered cathodes were used in the experiment, corresponding to three different sintering procedures. Nine cells contained 0.2 M LiOD in D2O as electrolyte. The tenth cell, containing a sintered cathode, was in 0.2 M LiOH in H2O.
Measurements of neutrons, tritium in the solution and in the recombined gases, gamma rays, and electrode temperature were carried out. When the current density reached the highest values, a marked increase of the neutron detector count rate with respect to the background level (2 count/h) was observed. The emissions occurred in bursts. This behavior was observed for approximately 10 days but only when the current density was set at > 320 mA/cm2. In the first part of that period, an excess of tritium with respect to the expected value calculated for the electrolytic enrichment was found in three cells out of nine (one of the cells was in light water). This excess was about twice the amount expected with respect to the enrichment and about four times the initial tritium content in the heavy water (267 decay/min.ml). The other cells, including the one in light water, did not show any excess tritium, the value of which was in good agreement with the calculated value. Some aspects concerning the thermal behavior of the electrodes are also discussed
X-ray, heat excess and He-4 in the D/Pd system (vol 435, pg 113, 1997)
No full textThe energy balance between heat excess and He-4 in the gas phase has been found to be reasonably satisfied even if the low levels of He-4 do not give the necessary confidence to state definitely that we are dealing with the fusion of deuterons to give He-4. In the melted cathode, the data of which are reported, no He-4 was found at the achieved sensitivity. X-ray film, positioned at 50 mm from the cell, roughly gave the image of the cathode through spots. Extended considerations have been made to explain this evidence on the basis of the bundle nature of the cathode. From these considerations, the energy of the radiation and the total energy associated to it have been extimated as 89 keV and 12 kJ, respectively. This value is approximate to 0.5% of the: energy measured by calorimetry in the same interval of time. The highest values of energy and excess power are 8.3 MJ and 10 W, respectively. (C) 1998 Elsevier Science S.A. All rights reserved
EVIDENCES FOR ASSOCIATED HEAT-GENERATION AND NUCLEAR PRODUCTS RELEASE IN PALLADIUM HEAVY-WATER ELECTROLYSIS
No full textIn a galvanostatic expt. of charging D in a Pd cathode, nuclear and thermal effects were found. A sintered Pd electrode shaped as a parallelepiped was used. After 6 days of electrolysis at 200 mA/cm2, a simultaneous emission of n, T excess in the electrolytic soln., and temp. rapid increase were obsd. During the event which lasted 4 min., an emission of 7.2 × 105 n was estd. while the electrode temp. reached 150°. Excess of T was evaluated to be (2.14 ± 0.04) × 1011 atoms. If the energy released as heat, 176 J, is compared with the energy assocd. to the d + d reactions, 0.1 J, 3 orders of magnitude are still defective. Electrode characterization after the events is reported
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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