Oxidation Reactions of Unsaturated Hydrocarbons for Fuel Cells

The anodic oxidation of unsaturated hydrocarbons has been the subject of numerous studies, primarily on Pt and Au electrodes at low temperatures, \u3c 100°C. The complete oxidation to CO2 is usually the predominant reaction with both H2O and OH- having been proposed as the oxygen source. Usually a single study consists of a comprehensive investigation of a single compound on a single electrode or a somewhat limited study of several compounds on a single electrode. A diversity of proposed mechanisms has resulted and is illustrated by the following summary

Neutron Diffraction Studies of NdₙFeₘ₋ₓ₋\u3csub\u3ey\u3c/sub\u3eVₓAl\u3csub\u3ey\u3c/sub\u3e [(n,m)=(1,12), (2,17), (3,29)]

Several NdnFem-x-yVxAly [(n,m)=(1,12), (2,17), (3,29)] samples were prepared and analyzed using neutron powder diffraction. Rietveld analysis of the neutron diffraction data indicates that the V and Al substituents take those sites with similar environments in all three phases, as observed in our previous study of Ti-substituted compounds. It was confirmed that the diffraction data of the 3:29 compound can be better refined using the A2/m space group than using the P21/c space group. The SQUID measurements show that all samples have Curie temperatures well above room temperature. The neutron diffraction results show that the easy direction is along the a axis for the 3:29 compounds, along the c axis for the 1:12 compounds and in the a-b plane for 2:17 compounds, respectively. The average site magnetic moments, the metal-metal bond lengths and the unit cell parameters of these compounds are compared with those of the Ti-substituted compounds

The Mechanism Of The Electrooxidation Of Acetylene On Gold

Acetylene has been oxidized anodically in aqueous solutions at 80 °C on gold electrodes. It was found that the partial oxidation to CO2 was accompanied by a polymer formation. Effects of potential, acetylene partial pressure, pH, and temperature on the rate (current) were measured. A discontinuity in the Tafel curves was noted that indicated a change in the reaction mechanism with potential. The discontinuity was also pH dependent. A mechanism involving the discharge of H2O and/or OH− has been proposed that is consistent with the experimental results. © 1967, The Electrochemical Society, Inc. All rights reserved

Neutron Diffraction Studies of ErNi₅₋ₓCoₓ (X=0.68, 1.68, 2.26) Alloys

ErNi5-xCox alloys were prepared by RF induction melting and analyzed using neutron powder diffraction. Rietveld analysis neutron diffraction data indicates the unit cell volume increases with Co content while the a and c lattice parameters show different dependencies on the composition. the Co atoms show higher affinity for the 3g sites than for the 2c sites. the Co sublattice tends to couple antiferromagnetically to the Er sublattice. the easy magnetization direction is along the c axis

Neutron Diffraction and Magnetic Studies of RFe₁₂₋ₓTₓC\u3csub\u3ey\u3c/sub\u3e (R=Y,Er; T=V,Ti,Mo) Alloys

RFe12-xTxCy, (R=Y,Er; T=V,Ti,Mo) alloys were prepared by rf induction melting and analyzed using neutron powder diffraction and superconducting quantum interference device (SQUID) measurements. Rietveld analysis of the neutron diffraction data indicates that V, Ti, and Mo atoms all prefer the 8i sites. The refined amount of carbon atoms found in the interstitial sites from neutron diffraction data is significantly less than the nominal carbon content. All samples have the easy direction along the c axis. The Er sublattice couples to the Fe sublattice antiferromagnetically. The average Fe site moments range from 1.3 to 2.8 μB. The anisotropies of the crystal structures are found to relate to both the rare earth atoms and the stabilizing transition metal atoms. The SQUID measurements show that all samples have a Curie temperature near 600 K

Perfection of the Lattice of Dislocation-Free Silicon, Studied by the Lattice-Constant and Density Method

The lattice-constant and density method revealed that a high-purity silicon crystal free of dislocations has a perfect lattice without an excess of vacant sites or interstitials (n′=8.0000 4) within the limits of error, in agreement with the results obtained with the decoration method. The lattice constant of vacuum heated silicon powder of semiconductor purity was 5.43070±0.00004 A; that of the nonheat-treated powder was 5.43081 A at 25°C. The constants determined from crystal chips by the rotating crystal method were lower: between 5.43028-5.43048 A at 25°C. As the constants of each series of measurements could be reproduced very well (s=±0.00004 A), the lower values suggested the presence of some unknown systematic errors, the magnitude of which is outside the scope of errors due to absorption. The thermal expansion coefficients of all samples between 10°-60°C were (2.6±0.4)×10 -6/°C. The average density of etched crystal chips was 2.3289±0.0001 g/cm 3. The lower density of the nonetched chips indicated the presence of microcracks, removable by etching, within the distorted surface layers. There was no significant difference in density of bars sawed, or of chips broken from the crystal and etched