[en] The magnetic hyperfine fields in the Heusler alloys Rh₂ Mn _.98 Ge Sn ₀₂, Rh₂ Mn Ge_.98 Sn_.02, Rh₂ Mn Pb _.98 Sn _.02 and Rh₂ Mn Sn has been studied by ¹¹⁹ Sn Moessbauer spectroscopy at 293 K, 77 K, 4.2 K and 293 K with applied external magnetic field. The results show that when one compare the magnetic hyperfine fields systematic with the Heusler alloys X₂ Mn Z (X = Co, Ni, Cu, Pd, and Z = s p metal), this systematic is similar to the Co alloys, although can not explained by the currents models for the Heusler alloys. (author)

[en] Short note

[en] High-resolution ion backscattering, combined with channeling and blocking, can provide sufficient depth resolution to extract information about thin-film morphology from the shape of the surface peaks in a backscattered ion spectrum. Such analyses have been applied to several metal-silicide systems in the past. We present a similar analysis for a reactive intermetallic system consisting of thin Pd films on Al(111). The Al surface peaks are fit using three-component peak shapes corresponding to 1. bare Al Surface, 2. buried Al surface, and 3. three-dimensional islands of AlPd compound. Assumptions, limitations, and conclusions from the analysis are discussed. (orig.)

[en] Requirements of thermionic electrode materials have emphasized the need for substantial improvements in microstructural stability, strength and creep resistance at service temperatures in excess of 2,500K. This study utilized both chemical alloying and mechanical alloying procedures for the addition of iridium to submicron W powder followed by cold compaction and sintering. The shrinkage characteristics and microstructural development were studied in iridium-added tungsten compacts with a range of additive levels. An electron-emission study was subsequently carried out in order to evaluate the work-function behavior of the consolidated alloys. The work function was obtained from current-emission measurements from the electrode surface under UHV conditions in the temperature range of 1,800 to 2,500K using a Vacuum Emission Vehicle (VEV). The data show that the magnitude of the work function in these alloys varied with temperature and was sensitive to sub-surface iridium content

[en] Using the levitation method, the dependence of magnetic susceptibility on pressure up to 2 kbar in vanadium, palladium and Pd_0,95Rh_0,05 alloy is studied at the temperatures 20.4 and 78 K. The results obtained and supplemented with data derived by other methods show a strong temperature dependence of the megnetovolume effect in palladium and the alloy and its invariance in vanadium. The low temperature data for pure metals are compared with theoretical calculation, which shows an appreciable discrepancy whose origin is not clear

[en] Palladium-silver cathodic membranes are used in industrial tritiated water processing to produce very high purity tritium gas and its isotopes. During electrolysis, these adsorb on the cathodic surface, diffuse through the alloy, and finally are desorbed on the side opposite of the cathodic entry surface. This desorption occurs in a gastight compartment separated from the electrolyzer allowing the recuperation of pure isotopes. The diffusion is dependent on cathodic surface, PdAg thickness, temperature, deposits on the surface to favor the adsorption, and applied cathodic potential. Here, the embrittlement of palladium and PdAg alloy cathode membranes and the diffusion and solubility parameters were studied in tritiated water. Voltammetry curves were plotted to ascertain the conditions of cathodic charging with tritium as well as the effect of radiolytic hydrogen peroxide on palladium or PdAg. From the voltammetric curves, the diffusion coefficient, the surface solubility of tritium, and the thickness of the palladium and PdAg alloy involved were determined. Scanning electron microscope examinations show that the cracking is transgranular in the case of palladium, while it appears to be intergranular for the PdAg allow. With palladium, this cracking involves all the surface subjected to charging, whereas for the alloy, only the surface at the electrolyzer gas atmosphere/electrolyte bordering zone would appear to be embrittled. This could be the result of the presence of two tritiated phases in palladium or in palladium-silver. The PdAg alloy is the less sensitive to embrittlement. 18 refs., 15 figs

[en] Surface roughness caused by the grain growth of the RuCr non-magnetic intermediate layer (NMIL) was evaluated using the X-ray total reflection method. In the case of Ru NMIL, the value of root mean square roughness of NMIL (σ) increases from 0.59 to 1.45 nm with increase in Ar gas pressure and/or thickness of the Ru layer. Judging from the loop slope and normalized coercivity, the degree of magnetic isolation increases as σ increases, independent of the Cr content of a RuCr NMIL. Furthermore, it was found that σ of NMIL is strongly correlated with wettability to the seed layer material and is enhanced by the lattice extension of NMIL

[en] Effective hydrogen pressure at hydrogen evolving cathode is discussed in connection with the mechanism of the hydrogen electrode reaction. A Nernst type expression involving hydrogen overpotential is not generally applicable. Experimental results on Pd and Pd-Ag alloy cathodes with and without addition of catalytic poison are presented. The highest pressure observed was ca. 10⁶ atm at 0.25 A cm^-2, 30degC. (author)

[en] The Fe_xPt_100−x nanoparticles (NPs) with different nominal atomic rations (30≤x≤80) were synthesized at 700 °C by the sol–gel method. The structure, morphology and magnetic properties of the samples were investigated. When the Fe content in the Fe–Pt alloy NPs was 30 at%, FePt₃ NPs were successfully synthesized. With the increase in Fe content up to 50 at%, it was found that the superlattice reflections (0 0 1) and (1 1 0) appeared, which indicated the formation of the L1₀-FePt phase. Meanwhile, the FePt₃ fraction was reduced. When the Fe content increased to 60 at%, single-phase L1₀-FePt NPs were synthesized. The coercivity (Hc), saturation magnetization (Ms) and chemical order parameter S for Fe₆₀Pt₄₀ NPs were as high as 10,200 Oe, 17.567 emu/g and 0.928, respectively. With the further increase of the Fe content to 80 at%, only Fe₃Pt phase existed and the Hc of the Fe₃Pt NPs decreased drastically to 360 Oe. - Graphical abstract: Fe₃Pt, FePt and FePt₃ nanoparticles was obtained by sol–gel method. The effect of iron and platinum content on structural and magnetic properties of the FePt nanoparticles was investigated. Display Omitted - Highlights: • L1₂-FePt₃, L1₀-FePt and L1₂-Fe₃Pt NPs were synthesized by sol–gel method. • The chemical order parameter S affects the magnetic properties of the Fe–Pt alloy. • Structural and magnetic properties of the Fe–Pt alloy NPs were studied. • The synthetic route in this study will open up the possibilities of practical use

No abstract available