Biography:

In the past C.B. Alcock has collaborated on articles with P.E. Potter and K.T. Jacob. One of their most recent publications is Thermodynamic study of the manganese/ manganous-oxide system by the use of solid oxide electrolytes☆. Which was published in journal Electrochimica Acta.

More information about C.B. Alcock research including statistics on their citations can be found on their Copernicus Academic profile page.

C.B. Alcock's Articles: (9)

Thermodynamic study of the manganese/ manganous-oxide system by the use of solid oxide electrolytes☆

AbstractThe free energy of formation of manganous oxide has been determined by measurement of the emfs of the cellsNi|NiO | ThO2-YO1.5 electrolyte | Mn|MnO andFe|Fe0.95O | Tho2-YO1.5 electrolyte | Mn|MnO in the temperature interval 923–1273°K. The results agree quite closely with calorimetric data for the reactionMn + 12O2 → MnO. The study thus demonstrates that the thoria-based oxide electrolytes can be used at temperatures around 1000°C for the study of the thermodynamics of oxide systems having oxygen dissociation pressures of about 10−24 atm.

Some chemical eouilibria for accident analysis in pressurised water reactor systems

AbstractSome chemical equilibria for the safety analysis of water reactor systems are discussed. Particular attention has been paid to the behaviour of the fission-product elements Cs, I and Te. An assessment of the thermodynamic properties of tellurium compounds has been made, and these values have been used in the calculations of the speciation of this element in appropriate conditions of temperature, concentration and mixtures of hydrogen and steam. In addition some assessments of the chemical forms of Ba, Sr and Ru have been made. Much use has been made of the program SOLGASMIX for the calculation of the complex equilibria involved.

Activities and their relation to cation distribution in NiAl2O4MgAl2O4 spinel solid solutions

AbstractThe activity of NiAl2O4 in NiAl2O4MgAl2O4 solid solutions has been measured by using a solid oxide galvanic cell of the type, Pt, Ni + NiAl2O4 + Al2O3(α)/CaOZrO2/Ni + NixMg1−xAl2O4 + Al2O3(α). Pt, in the temperature range 750–1150°C. The activities in the spinel solid solutions show negative deviations from Raoult's law. The cation distribution in the solid solutions has been calculated using site preference energies independent of composition for Ni2+, Mg2+, and Al3+ ions obtained from crystal field theory and measured cation disorder in pure NiAl2O4 and MgAl2O4, and assumi g ideal mixing of cations on the tetrahedral and octahedral positions. The calculated values correctly predict the decrease in the fraction, α, of Ni2+ ions on tetrahedral sites for 1>x>0.25, observed by Porta et al. [J. Solid State Chem. 11, 135 (1974)] but do not support their tentative evidence for an increase in α for x < 0.25. The measured excess free energy of mixing can be completely accounted for by using either the calculated or the measured cation distributions. This suggests that the Madelung energy is approximately a linear function of composition in the solid solutions. The composition of NiOMgO solid solutions in equilibrium with NiAl2O4MgAl2O4 solid solutions has been calculated from the results and information available in literature.

Some observations on activation of FeTi for hydrogen absorption☆

AbstractWe used reflection and transmission electron microscopy and measurements of magnetization to examine structural changes at and near the surface of FeTi which had been activated for hydrogen gas absorption. These measurements were coupled with determinations of the absorption kinetics and absorption isotherms for such activated samples. We present a description of the observed changes resulting from hydrogen activation and, in particular, evidence that formation of metallic iron in the cycling process used to give these samples their ability to absorb hydrogen is, at most, a minor feature of these changes.

New electrochemical sensors for oxygen determination

AbstractOxygen sensors which can operate in wider oxygen pressure and temperature ranges than currently used stabilized zirconia-based oxygen sensors are described. Strontium fluoride-lanthanum fluoride solid solution electrolytes have higher conductivities than zirconia and, when dispersed with an oxide phase, can operate at lower temperatures and oxygen partial pressures than zirconia-based oxygen sensors. Other potential electrolyte materials for low oxygen partial pressure applications are some very stable perovskite oxides, which are pure oxide-ion conductors at lower oxygen partial pressures than stabilized zirconia. In high-temperature aggressive environments, the lifetime of zirconia-based oxygen sensors can be extended through the use of a non-isothermal sensor, in which the temperature of the reference electrode is reduced.

Oxygen pumping characteristics of oxide ion electrolytes at low temperatures

AbstractElectrochemical oxygen pumping was employed to study oxygen transport characteristics of electrolytes and electrodes. Oxygen transference numbers were measured by measuring volume changes using a liquid column in a capillary. The two electrolytes used were 10 mol% Ca doped CeO2 and 20 mol% Sr doped Bi2O3. The electrodes used were Pt, Pd/Au, La0.7Sr0.3MnO3−δ, La0.5Sr0.5MnO3−δ, and La0.7Sr0.3FeO3−δ. The manganite perovskite electrode performance was comparable to Pt at 700°C on both electrolytes. The bismuth electrolyte was found to be reduced to metal on the cathode side at high current densities.

A thermogravimetric analysis of Sr14−xCaxCu24Oy

AbstractA thermogravimetric analysis was conducted on the incommensurate structure of Sr14−xCaxCu24O41 (0≤x≤5). This compound is only stable at an oxygen partial pressure greater than 6 kPa at 1193 K. The substitution of Sr by Ca did not show any significant influence on the oxygen content and the decomposition oxygen partial pressure.

Chapter 6 - Rate processes in metals and alloys

Publisher SummaryIn the whole series of oxides, the basic unit structure of the systems consists of a metal ion coordinated octahedrally by six oxygen ions. When each octahedron touches its neighbors only at the corners, then each oxygen ion is shared by two metal ions, and the compound formula is MO3. If oxygen ions are removed by a chemical reduction process, then isolated point defects are formed where the ions are removed. The situation in which these point defects are randomly distributed throughout the structure corresponds to the nonstoichiometric oxide case. It has been found, however, that such a random distribution only occurs for a very small value of δ and that with increasing departure from stoichiometry, a new phenomenon arises that can give rise to a large number of stable intermediate oxides between MO3 and MO2. An important feature of oxide systems is that nonstoichiometry can also be achieved by the substitution of aliovalent ions that change the charge balance between cations and anions.

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