Browsing by Author "Flanagan, Ted B."

Now showing 1 - 4 of 4

Calorimetric Determination of Differential Heats of Absorption of Hydrogen by Palladium
(Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1974, 70 (1-6), 1974) Lynch, J. F.; Flanagan, Ted B.
Differential heats of absorption of hydrogen by palladium have been measured with an adiabatic calorimeter. For the first time calorimetric heats have been determined for bulk palladium in the single phase, α and β, regions. The heat of absorption in the α-phase (25°C) was found to be 23.32 ± 4.45 kJ (mol H2)–1 and in the β-phase the isosteric heats decrease with hydrogen content from 46.5 (H-to-Pd = 0.61) to 27.3(H-to-Pd = 0.69). (The measured differential (adiabatic) heats have been corrected for compression work to give isosteric heats.) Heats of sorption determined in the α-phase of palladium black reflect contributions due to both absorption and chemisorption of hydrogen. Some preliminary heats of sorption are also reported at – 78°C and at –195°C with palladium black.
Isotope effect for the solution of hydrogen in metals: application to Pd/H(D)
(Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1977, 73 (03), 1977) Oates, W. A.; Flanagan, Ted B.
The isotope effect for the solution of hydrogen in metals cannot be described over the whole temperature range by the usually employed model of localized oscillators. Consideration is given to the transition from localized harmonic oscillator behaviour at the lowest temperatures to that of a three-dimensional translator at the highest temperatures. Application of this new model to the Pd/H(D) system reveals that the experimental isotope solubility ratio data do not agree with the theoretical expectations. At low temperatures the isotope data are in disagreement with the Einstein characteristic temperature, θH= 795 K, determined by inelastic neutron scattering, if θD=θH/√2 is assumed. The isotopic solubility ratio data are also contrary to expectations at higher temperatures. The discrepancies are removed if it is assumed that θD=θH/1.53, a choice which is not unrealistic in view of recent interpretations of the inverse isotope effect observed for the super-conductive transition temperatures of Pd/H(D) alloys.
Protonic Conductivity in Copper Formate Tetrahydrate
(Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1977, 73 (09), 1977) Murphy, Kathleen E.; Flanagan, Ted B.
The conductivities of single crystals of copper formate tetrahydrate (CFT) have been determined along the three principal crystallographic axes with proton-injecting electrodes. The ohmic conductivities at 298 K are: 5.5 ± 1.6 × 10–7Ω–1 cm–1(along the b-axis), 8.5 ± 2.1 × 10–8Ω–1 cm–1(along the a-axis) and 7 ± 2 × 10–12Ω–1 cm–1(along the c axis). Since the H-bonded network lies in the ab-plane, the observed anisotropy of conduction suggests protonic conductivity. The Arrhenius plot of σ exhibits a change of slope and a transition to a lower conductivity at the paraelectric → antiferroelectric phase change (235 K). The energies of activation for conduction within the ab-plane are 0.56 eV above 235 K and 0.65 eV below 235 K. The tetradeuterate has an ohmic conductivity approximately an order of magnitude lower than the tetrahydrate (within the ab-plane). Space-charge-limited currents are observed at high fields. The CFT crystals behave as semipermeable membranes to protons and this supports the view that protons are mobile within CFT. If conduction is indeed protonic, CFT is a very ready hydrate protonic conductor exhibiting a conduction greater than ice.
Thermodynamic Properties of Hydrogen and Deuterium Dissolved in Palladium at Low Concentrations over a Wide Temperature Range
(Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1973, 69 (2), 1973) Clewley, J. D.; Curran, T.; Flanagan, Ted B.; Oates, W. A.
The equilibrium pressures of the Pd/H2 and Pd/D2 systems have been measured in the tempera ture range from — 100°C to 35O°C for values of H(D)-to-Pd, atomic ratio, in the approximate range from 0.0005 to 0.005. These data were obtained in an ultra-high vacuum apparatus with large samples of low surface area. Partial thermodynamic data have been obtained from these equilibrium data; a significant temperature dependence is reported for the relative partial molar enthalpies and entropies.