Effect Of Hydrogen Absorption Research Articles

Hydrogen absorption in La 2−xSr xCuO 4 with mono-layer CuO 6 octahedra

Hydrogen absorption effect on the magnetic-superconducting phase diagram of La 2−x Sr x CuO 4 have been studied. Upon hydrogenation, the superconducting transition temperature T c increases for x>0.15, while T c decreases for x N of La 2 CuO 4 rises up to 324K from 240K. These facts suggest that the doped hydrogen in La 2−x Sr x CuO 4 system plays a role of electron donor to the CuO 2 plane like in other high-T c copper oxides.

Activation energy of obliquely deposited FeTi and FeTiH x thin films

The effect of hydrogen absorption on the electrical resistance and activation energy of FeTi thin films was investigated. The samples were prepared by oblique deposition at different angles ( θ = 0°, 30°, 45°, 60° and 75°) simultaneously. The resistance and activation energy of FeTi films increases with the angle of deposition. The activation energy of FeTiH x films is found to be higher than FeTi films for the same deposition angle and also increases with angle of deposition. The activation energy of hydrogenated samples is found to increase with hydrogen charge and discharge cycling.

Hydrogen intercalation in some superconducting copper oxides

Abstract Effect of hydrogen absorption on superconducting and transport properties has been studied on YBa 2 Cu 3 O 6.9 , Bi 2 Sr 2 CaCu 2 O 8+y and Bi 1.6 Pb 0.4 Sr 2 Ca 2 Cu 3 O 10+y . We found that the introduction of hydrogen into the system decreases one hole carrier per one hydrogen. The variation of T c with hydrogen concentration strongly depends on the preferential site occupation of hydrogen. Our results support the model that T c is largely determined by the concentration of mobile holes on the CuO 2 plane.

Hydrogen sensitivity of Pd/SiO 2/Si structure: A correlation with the hydrogen-induced modifications on optical and transport properties of α-phase Pd films

The effects of hydrogen absorption and desorption in Pd films are studied through reflectivity and conductance measurements. The data show that there is an appreciable variation in both signals even when the sample is exposed to a low hydrogen concentration that does not induce the αβ transition. The reflectivity variations are explained in terms of a rise of the Fermi level in the bulk of the Pd film, while the conductance decrease in a hydrogen atmosphere is related to the behaviour of scattering centres of the absorbed hydrogen atoms. Such ‘bulk’ effects are correlated to the flat-band voltage shift measured in Pd-gate MOS capacitors and two contributions to this quantity are isolated by a temporal analysis of the processes. A model based on two different sites for the absorbed hydrogen atoms is proposed to explain the results.

ChemInform Abstract: Effects of Hydrogen Absorption on the 3d and 4f Anisotropies in RE2Fe14B (Re: Y, Nd, Ho, Tm)

Abstractare investigated using the singular point detection technique in the temp. range 77‐293.

Effects of hydrogen absorption on the 3d and 4f anisotropies in RE2Fe14B (RE ≡ Y, Nd, Ho, Tm)

Abstract The effects of hydrogen absorption on the iron and rare earth sublattice anisotropies in RE2Fe14B (RE ≡ Y, Nd, Ho, Tm) have been investigated using the singular point detection technique. Hydrogen is found to substantially depress both the iron and rare earth contributions to the magnetocrystalline anisotropy. However, such a reduction appears to be very large for holmium, and particularly for neodymium, which both give a resultant axial anisotropy. It is less important in the case of thulium which gives a resultant planar anisotropy. The observed hydrogen composition dependence of the holmium anisotropy implies the existence of a particular hydrogen filling sequence.

ChemInform Abstract: Effects of Hydrogen Absorption on the Electrical Resistivity of LaCo5 Films and the Determination of the Hydrogen Content in the Films.

AbstractThe electrical resistivity of amorphous LaCo5 films is found to increase during absorption of hydrogen.

Effects of hydrogen absorption on the electrical resistivity of LaCo 5 films and the determination of the hydrogen content in the films

Electrical resistivities of amorphous LaCo 5 films were measured under an atmosphere of hydrogen. The resistivity increased during the absorption of hydrogen. Hydrogen in the film seems to exist as hydrogen anions. The effect of film thickness on the electrical properties during the hydrogen absorption-desorption process was also studied. The hydrogen content in LaCo 5 films of various thickness was determined using a quartz crystal mass monitoring (QCMM) method. The hydrogen concentration increased with increasing film thickness. In pressurecomposition isotherms, the H LaCo 5 ratio was found to increase monotonously with an increase in pressure, while a pressure plateau was absent.

Effect of hydrogen absorption on the magnetic properties of Nd 15Fe 77B 8

Hydrogen-induced changes in the magnetic properties of the permanent magnetic material Nd 15Fe 77B 8 are reported. Increases in the magnetization and in the 57Fe hyperfine field were observed. In contrast, hydrogen absorption substantially reduced the anisotropy contribution of the neodymium sublattice. As a consequence the spin reorientation temperature, although still present in the hydride was shifted to lower values. Unless the hydrogen was removed by a heat treatment only limited values for the energy product ( BH) max were obtained. From analysis of the Mössbauer spectra we presume that the occupation numbers at certain iron sites differ from those in the parent compound. This, together with the selective oxidation of neodymium, may cause the formation of free metallic iron.

Effect of hydrogen absorption on the electronic and structural properties of V-Fe alloys

Effect of hydrogen absorption on the electronic and structural properties of V-Fe alloys

Effect of hydrogen absorption on the hyperfine interactions in Zr(Fe1−xMnx)2

Mossbauer studies have been carried out on Zr(Fe,Mn)2 and the corresponding hydrides. Hydrogen absorption is shown to lead to a substantial increase in magnetic ordering. Positive changes in isomer shift up to 0.53 mm/s have been observed which is explained in terms of a 4s carge transfer resulting in the formation of metal-hydrogen bands.

Role of hydrogen embrittlement in the corrosion cracking of aluminum alloys

The authors examine significant experimental and theoretical material related to the hydrogen embrittlement of aluminum alloys and systemize them for the purpose of obtaining a qualitative picture of the role of hydrogen embrittlement in corrosion cracking and determination of the influence of metallurgical factors on both phenomena. Conditions of hydrogen absorption, the reaction of hydrogen with crystalline structure defects, the microstructural effects of hydrogen absorption, and transport through an oxide film are discussed. The authors examine the influence of hydrogen absorption on corrosion cracking, the structure of fractures in hydrogen embrittlement, and the hypotheses of the mechanism of hydrogen embrittlement in corrosion cracking. The transport of hydrogen with the metal is discussed and the embrittlement of metal is examined.

Hydrogen absorption in CuTi metallic glasses. I. X-ray diffraction measurements

The effect of hydrogen absorption on the atomic structures of some CuTi glasses has been investigated by X-ray diffraction. The dependence on composition has been studied using three alloy compositions, Cu0.50Ti0.50, Cu0.58Ti0.42 and Cu0.66Ti0.34, and the influence of loading increasing amounts of hydrogen investigated for the latter two compositions. It is confirmed that these glasses can accept significant quantities of hydrogen to form amorphous hydrides and that the process is limited by a dissociation reaction involving the formation of titanium hydride TiH2 and free copper. Quite characteristic changes in the structure factor are produced by hydrogen loading and these are reflected in definite changes in the radial distribution function, similar to those observed elsewhere for other metallic glass-hydrogen systems. The results obtained in this study are in broad agreement with the conclusions of independent bulk measurements on CuTi-H glasses.

Influence of hydrogen on the magnetic properties of YCo compounds

The effect of hydrogen absorption on the magnetic properties of the Y 2Co 7H x and the YCo 3H x systems was examined in situ. The two systems show similar β and γ phase formation and magnetic behaviour. The β phase exhibits the anomaly that a slight hydrogen enrichment induces a substantial increase in the cobalt moment which varies from a minimum on the low concentration side (0.13 μ B in Y 2Co 7H 2 and 0.15 μ B in YCo 3H) to a maximum on the high concentration side (1.2 μ B in Y 2Co 7H 3 and 0.7 μ B in YCo 3H 2). These maximum values are almost equal to those in the respective uncharged compounds. The cobalt moment in the γ phase decreases with increasing hydrogen concentration in the same way as in ordinary cobalt-based ferromagnets. Both systems tend to lose ferromagnetism in the most hydrogenated compounds Y 2Co 7H 8 and YCo 3H 4. The anomalous dependence of the cobalt moment on composition is discussed.

Preparation of LaNi5 Films and Effects of Hydrogen Absorption on Electrical Resistivities of the Films

Abstract Thin films of LaNi5 have been prepared by means of a flash evaporation-deposition technique. Electric resistivity measurements on these films were carried out in an atmosphere of hydrogen. The films formed on quartz substrates were amorphous. Resistivities initially increased and then decreased during the absorption of hydrogen. During the desorption process, the reverse phenomenon was observed. The effect of the thickness of the films on the electric properties, during the hydrogen absorption-desorption process, was also studied. Sample pulverization could be avoidable by using films of less than 10 μm in thickness. The hydrogen contents of the films were determined by the quartz-crystal mass-monitoring (QCMM) method.

The effect of hydrogen absorption on the electrical resistivities of SmCo5 and LaNi5 films

The effect of hydrogen absorption on the electrical resistivities of SmCo5 and LaNi5 films

プロペラ軸用Ti-6Al-4V合金の性質

The corrosion behavior of such materials composing a ship as Ti-6Al-4V for propeller shaft, an Al-Mg alloy for body and Al-bronze for propeller are investigated. A kind of Al-Zn-Ga alloy is found out to be a good sacrificial anode. The good properties are proved by a corrosion test in real sea water for a year, too.A crevice corrosion test is carried out to check the corrosion behavior of propeller shaft coupled with a kind of stainless steel, and proved to be no problem.The effects of hydrogen absorption on the mechanical properties of Ti-6Al-4V is examined, and it shows no change up to about 1000ppm in the case of specimen absorbing it uniformly.The size effect of fatigue strength of Ti-6Al-4V is proved to be no more than that of steels.The propagation rate of fatigue crack in synthetic sea water is proved to be equal to that in air, if Ti-6Al-4V is applied under cathodic protection.

Supported PdPt alloy catalysts: Synthesis, structure characterization and effects of hydrogen absorption

Pd Pt alloy catalysts were prepared by anchoring Pd(II) and Pt(II) organometallic species to the support surface, followed by H 2 reduction under mild conditions. This preparation method was exploited for the synthesis of Pd Pt catalysts having different Pd Pt ratios and with total metal loading ~2%; pure Pd and pure Pt catalysts were also obtained. Small Angle X-ray Scattering (SAXS) analysis was used to determine metal dispersion: average metal particle diameter was in the range 20–40 Å both for alloy and single Pd and Pt catalysts. The occurrence of Pd Pt alloy formation was demonstrated by Wide Angle X-ray Scattering (WAXS) and Radial Distribution Function (RDF) analyses. Results both from WAXS and RDF are consistent with each other in ascertaining alloy occurrence, also providing a detailed picture of the behavior of Pt, Pd, and Pd Pt systems in the presence of H 2.

Magnetism and hydrogen absorption in rare-earth glasses

Measurements are reported on the magnetic properties and phase transitions in rare-earth-rich metallic glasses, and upon the effect of hydrogen absorption on these properties. The glasses have the nominal form R xGd 72−xG 28 where R represents either nonmagnetic La or anisotropic Tb and G represents glass formers Ga, B, Fe or mixtures thereof. Ferromagnetic, spin-glass, and double transitions are observed and H absorption, at the level H/M ⋍ 2, has a major effect on these transitions.

Effect of Hydrogen Absorption on the Hyperfine Field of Iron in Amorphous Fe<SUB>91</SUB>Zr<SUB>9</SUB> Alloy

Effect of Hydrogen Absorption on the Hyperfine Field of Iron in Amorphous Fe<SUB>91</SUB>Zr<SUB>9</SUB> Alloy