Atomic displacements in palladium/ platinum solid solutions

X-ray measurements reveal that Pd/Pt solid-solution alloys have higher Debye temperatures and lower root-mean-square dynamic displacements than the average for the pure metals. The root-mean-square static displacements are quantitatively interpreted in terms of a shortening of the Pd/Pt interatomic distance and the asymmetry of unlike neighbours about an average atom.     

Finding new phases for precipitate-hardening in platinum and palladium alloys

Precipitate hardening (via ordered phases rather than phase separation) of platinum and palladium can be effective even with a small volume-fraction of the ordered phase [M. Carelse, C.I. Lang, Scripta Materialia 54 (7) (2006) 1311]. The approach is particularly well suited to jewelry alloys which must be 95 wt.% pure and where ordered phases of 7:1 or 8:1 stoichiometries can be formed. We examined eight systems where this approach may lead to new applications: Pt-Al, Pd-Al, Pd-Cu, Pd-Mg, Pd-Nb, Pt-Mo, Pt-V, and Pd-V. In each system, using first-principles-based cluster expansion modeling, we have identified high stoichiometric-ratio phases that are stable. Furthermore, using Monte Carlo simulations, we have estimated the order-disorder transition temperatures to identify experimentally feasible phases. In three cases, the computational results are verified by experiment, suggesting that the remaining predictions are likely to be useful as well.     

Inhomogeneous nucleation and growth of palladium and alloyed cobalt during self-aligned capping of advanced copper interconnects

We investigate the nucleation and growth of two cobalt alloys (CoWB and Pd-CoWP) used to encapsulate copper interconnects. We demonstrate that very uniform deposits are obtained across 300 mm wafers, with accurate thickness control. However, large local thickness variations are observed, possibly compromising the continuity of thin deposits. The origin of this phenomenon is first investigated by electron back scatter diffraction. A clear correlation between areas of dense Pd nucleation and the (111) grains of the polycrystalline copper surface is demonstrated. Then, an epitaxial relationship between the cobalt alloys and the underlying copper substrate is evidenced by TEM characterization. Local nucleation density could thus be affected by the substrate orientation, accounting for thickness inhomogeneities after growth.     

Sorption-atomic-absorption determination of platinum,palladium, and rhodium in dead autocatalysts

The conditions for determination and group concentration of platinum metals (PMs) in the presence of matrix components using new S,N-containing complex-forming sorbents in solutions obtained after decomposition of decontaminated autocatalysts are proposed. The technique of atomic-absorption determination of PMs from a solution (n × 10⁻⁴−n × 10⁻²; s _r = 0.15–0.07) and a solid phase (n × 10⁻⁵−n × 10⁻⁴; s _r = 0.20–0.12) is developed.     

Age-hardening reactions and microstructures of a dental gold alloy with palladium and platinum

The age-hardening reactions and microstructures of a dental casting gold alloy with some palladium and platinum were investigated by means of hardness tests, X-ray diffractometry, electrical resistivity measurements, and scanning and transmission electron microscopy. Ageing reactions during isothermal annealing were completed by two stages. The first stage corresponded to the formation of a metastable CuAu I phase within grains, and the second stage to a cellular reaction at grain boundaries. The former contributed to the hardening and the latter to the softening. An activation energy of 128 kJ mol^–1 for hardening was obtained. Two types of cell growth were observed and could be distinguished in terms of the homologous temperature.     

Homoleptic single molecular precursors for the deposition of platinum and palladium chalcogenide thin films

Platinum and palladium dithio/diselenoimidodiphosphinato complexes have been synthesized and used as single source precursors for the deposition of platinum and palladium chalcogenide thin films by the Low Pressure Chemical Vapour Deposition technique. Pure PtSe₂ thin films were deposited at varying temperatures from the [Pt{N(SePⁱPr₂)₂}₂] complex. However, only Pt films were obtained from the sulfur analogue. The palladium diselenoimidodiphosphinato complex gave palladium selenide films with different stochiometries depending on the growth temperature. The corresponding sulfur complex gave PdS₂ films with a regular platelet-like morphology.     

Direct atomic-absorption determination of platinum,palladium, and rhodium in dead ceramic-based autocatalysts

The data on the effect of different concentrations of components of dead automobile catalysts on determination of platinum, palladium, and rhodium using the method of ETAAS are obtained and systematized. The conditions for direct atomic-absorption determination of Pt, Pd, and Rh are optimized. The technique of atomic-absorption determination of PM in secondary raw and technogenic materials is developed (n × 10⁻⁴−n × 10⁻¹ wt %, s _r = 0.12–0.07).     

Effect of platinum oxidation on the characteristics of standard platinum resistance thermometers

Platinum oxidation in PTS-10 and PTS-25 standard platinum resistance thermometers has been studied. The experimental results show that heat treatment of a thermometer at 100–300°C can increase its resistance at the triple point of water by the equivalent of 1.5 mK. A procedure for calibration in the range 0–450°C is recommended. Translated from Izmeritel'naya Tekhnika, No. 7, pp. 41–44, July, 1996.     

A tem study of activated FeTi surface

Transmission electron microscopy was used to study FeTi samples that had undergone activation treatments at low oxygen pressure. Activation treatments resulted in the formation of oxygen-stabilized Ti₄Fe₂O_x precipitates in the surface layers. In addition at 0.1 Pa oxygen pressure TiO is formed, while TiO₂ and Fe₃O₄ are formed both at low and high oxygen pressure treatments.     

High-strength oxide ceramics joints obtained by diffusion bonding with the use of platinum and palladium gaskets

Alumina and zirconia ceramics joints were made by diffusion bonding through platinum and palladium gaskets in air at temperatures between 1300 and 1550°C. The instrumentation and the procedure for these joints manufacturing are described. The effects of temperature, pressure and exposition time on 3-pt bending strength of resulting joints were established. The maximum bending strength of the samples reached 500 MPa. During thermal resistance testing the samples withstood several hundreds of thermal cycles at temperatures up to 800°C in air.     

Nanoindentation and nanomachining characteristics of gold and platinum thin films

Molecular dynamics (MD) simulation and an experimental method were carried out to study the effects of applied load, hold time, and temperature on nanoscratching and nanoindentation of gold and platinum thin films. The simulated results showed that the wear depth of gold decreased as the scratching velocity was increased and the temperature was decreased. The results also indicated that when the simulated nanoindentation of gold film hold time was increased, the plastic indentation depth and the plastic energy both increased. In addition, the experimental results showed that the groove depth for gold films was larger than that of platinum films under the same machining load. The wear depth and the surface roughness of platinum films were larger than those of gold films under the same lateral machining feed. Furthermore, the simulated plastic energy of gold films was compared during nanoindentation test.     

Effect of silver and palladium on dye-removal characteristics of anatase-titania nanotubes

Anatase-titania nanotubes have been synthesized via hydrothermal and surface-modified by depositing silver and palladium via ultraviolet-reduction method. The pure and surface-modified anatase-titania nanotubes have been characterized using the transmission electron microscope, selected-area electron diffraction, X-ray diffraction, diffuse reflectance, photoluminescence, and Fourier transform infrared spectroscope to reveal their average size, structure, and surface-chemistry. The nanotubes have been utilized for the dye-removal application involving the surface-adsorption mechanism under the dark-condition and photocatalytic degradation mechanism under the ultraviolet-radiation exposure. The variation in the dye-concentration during the dye-adsorption and photocatalysis processes has been determined using the ultraviolet-visible absorption spectrophotometer with methylene blue as a model catalytic dye-agent. It has been shown that silver-deposited anatase-titania nanotubes are more effective in enhancing the kinetics of the dye-removal via surface-adsorption and photocatalytic degradation mechanisms relative to the palladium-deposited anatase-titania nanotubes, which has been attributed to the differences in the surface-chemistry of anatase-titania nanotubes induced by the respective metal-deposition.     

FeTi系贮氢合金的研究进展

ＦｅＴｉ系贮氢合金是一类重要的贮氢材料,作为贮氢介质具有贮氢量大、价格便宜等优点,但活化性能和抗中毒性能较差。本文详细综述了ＦｅＴｉ系贮氢合金的氢化性能、活化机理以及改性处理等方面的内容。     

镁的氢化反应对氢化燃烧合成储氢合金Mg2NiH4纯度的影响

本文主要通过改变在镁氢化反应温度的保温时间,研究不同合成压力、合成温度下,中间反应-镁的氢化反应对氢化燃烧合成Mg2NiH4的影响.初步探讨了镁的氢化反应与燃烧合成Mg2Ni反应及其氢化反应的内在联系.研究结果表明:镁的充分氢化在促进Mg-Ni燃烧合成反应的同时有效地提高了Mg2Ni的氢化活性,这一结果为工业化低压合成纯Mg2NiH4提供了可行途径,但在低温下仅延长镁的氢化时间,产物中少量的Ni很难消除.