X-ray reflectivity studies of the metal/solution interphase

We have designed an electrochemical cell that permits x-ray scattering studies in a transmission geometry under in-situ electrochemical control and have performed x-ray specular reflectivity studies of several metal/solution interphases as a function of electrochemical potential. For the copper/solution interphase, we found that the reflectivity changes upon oxidation and reduction, indicating a phase transition between copper and copper oxide at the interphase. We also found that the thickness of the pure copper and the roughness of the interfaces exhibited electrochemical irreversibility that is consistent with the potentials for the oxidation waves in the anodic sweep and the reduction waves in the cathodic sweep of the voltammogram. A standard Fresnel expression for the x-ray specular reflectivity was applied in the data analysis, and a smoothly varying Lorentzian interface profile was used for the individual rough interfaces. Furthermore, an incoherent average was used to include the effect of correlated roughness between a pair of interfaces. Preliminary results are also presented for the silver/solution and platinum/solution interphases. 14 refs., 9 figs., 2 tabs

Electrochemical cell and electrode designs for high-temperature/high-pressure kinetic measurements

Many corrosion processes of interest to the nuclear power industry occur in high-temperature/high-pressure aqueous systems. The investigation of the kinetics of the appropriate electrode reactions is a serious experimental challenge, partially because of the high temperatures and pressures and partially because many of these reactions are very rapid, requiring fast relaxation measurements. An electrochemical measuring system is described which is suitable for measurements of the kinetics of fast electrode reactions at temperatures extending to at least 300C and pressures to at least 10 MPa (100 atmospheres). The system includes solution preparation and handling equipment, the electrochemical cell, and several electrode designs. One of the new designs is a coaxial working electrode-counter electrode assembly; this electrode can be used with very fast-rising pulses, and it provides a well defined, repeatedly-polishable working surface. Low-impedance reference electrodes are also described, based on electrode concepts responding to the pH or the redox potential of the test solution. Additionally, a novel, long-life primary reference electrode design is reported, based on a modification of the external, pressure-balanced Ag/AgCl reference electrode

3,5-Di-tert-butyl-1,2-benzoquinone Cleaves a CC-bond in Vicinal Aminobenzyl Alcohols

Two vicinal aminobenzyl alcohols, L-threo-1-(4-methylthiophenyl)-2-amino-1,3-propanediol (IIa) and 1-phenyl-2-amino-1,3-propanediol (IIb), underwent, under mild conditions, CC-bond cleavage with 3,5-di-tert-butyl-1,2-benzoquinone (I) producing in high yields 4-methylthiobenzaldehyde (Va) and benzaldehyde (Vb), respectively, and 2-hydroxymethyl-4,6-di-tert-butylbenzoxazole (VII). Ethanolamine (VIII) under identical conditions produced benzoxazole VII. The reported reaction is a second case in which quinone I mimics reactions of pyridoxal.</jats:p

The current status of fusion reactor blanket thermodynamics

This report addresses the current status of fusion reactor blanket thermodynamics

Argonne National Laboratory Reports

The available thermodynamic information is reviewed for three categories of materials that meet essential criteria for use as breeding blankets in deuterium-tritium (D-T) fueled fusion reactors: liquid lithium, solid lithium alloys, and lithium-containing ceramics. The leading candidate, liquid lithium, which also has potential for use as a coolant, has been studied more extensively than have the solid alloys or ceramics