Temperature dependence of hydrogen overvoltage on nickel and iron in acid solution

2000 ◽  
Vol 36 (11) ◽  
pp. 1174-1178 ◽  
Author(s):  
J. Tamm ◽  
L. Tamm ◽  
P. Vares
Author(s):  
E. P. Abrahamson II ◽  
M. W. Dumais

In a transmission microscopy study of iron and dilute iron base alloys, it was determined that it is possible to preserve specimens for extended periods of time. Our specimens were prepunched from 5 to 8 mil sheet to microscope size and annealed for several hours at 700°C. They were then thinned in a glacial acetic-12 percent perchloric acid solution using 10 volts and 20 milliamperes, at a temperature of 8 to 14°C.It was noted that by the use of a cold stage, the same specimen can be observed for periods up to one week without excess contamination. When removal of the specimen from the column becomes necessary, it was observed that a specimen may be kept for later observation in 1,2 dichloroethene or methanol for periods in excess of two weeks.


Author(s):  
Kenneth H. Downing ◽  
Robert M. Glaeser

The structural damage of molecules irradiated by electrons is generally considered to occur in two steps. The direct result of inelastic scattering events is the disruption of covalent bonds. Following changes in bond structure, movement of the constituent atoms produces permanent distortions of the molecules. Since at least the second step should show a strong temperature dependence, it was to be expected that cooling a specimen should extend its lifetime in the electron beam. This result has been found in a large number of experiments, but the degree to which cooling the specimen enhances its resistance to radiation damage has been found to vary widely with specimen types.


Author(s):  
Michio Ashida ◽  
Yasukiyo Ueda

An anodic oxide film is formed on aluminum in an acidic elecrolyte during anodizing. The structure of the oxide film was observed directly by carbon replica method(l) and ultra-thin sectioning method(2). The oxide film consists of barrier layer and porous layer constructed with fine hexagonal cellular structure. The diameter of micro pores and the thickness of barrier layer depend on the applying voltage and electrolyte. Because the dimension of the pore corresponds to that of colloidal particles, many metals deposit in the pores. When the oxide film is treated as anode in emulsion of polyelectrolyte, the emulsion particles migrate onto the film and deposit on it. We investigated the behavior of the emulsion particles during electrodeposition.Aluminum foils (99.3%) were anodized in either 0.25M oxalic acid solution at 30°C or 3M sulfuric acid solution at 20°C. After washing with distilled water, the oxide films used as anode were coated with emulsion particles by applying voltage of 200V and then they were cured at 190°C for 30 minutes.


Author(s):  
Sonoko Tsukahara ◽  
Tadami Taoka ◽  
Hisao Nishizawa

The high voltage Lorentz microscopy was successfully used to observe changes with temperature; of domain structures and metallurgical structures in an iron film set on the hot stage combined with a goniometer. The microscope used was the JEM-1000 EM which was operated with the objective lens current cut off to eliminate the magnetic field in the specimen position. Single crystal films with an (001) plane were prepared by the epitaxial growth of evaporated iron on a cleaved (001) plane of a rocksalt substrate. They had a uniform thickness from 1000 to 7000 Å.The figure shows the temperature dependence of magnetic domain structure with its corresponding deflection pattern and metallurgical structure observed in a 4500 Å iron film. In general, with increase of temperature, the straight domain walls decrease in their width (at 400°C), curve in an iregular shape (600°C) and then vanish (790°C). The ripple structures with cross-tie walls are observed below the Curie temperature.


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