Ruthenium Films Research Articles

Modification of glassy carbon with a stable film containing iridium oxide and palladium

Many potential applications of modified electrodes require the immobilization of catalytic centers at the electrode surface. Although most reports in this regard have dealt with the use of films of organic ionomers as the host, success has also been achieved with purely inorganic films. The latter are particularly attractive because of the greater stability that can be envisioned by using solubility-limited systems rather than films in which the mediator is bound by an ion-exchange reaction. Neff and co-workers prepared and characterized electrodes that were modified by adsorption of films of Prussian Blue [1,2] and its ruthenium analogue [3]. In a variation of their approach, we demonstrated that catalytically active films were electrodeposited by cyclic voltammetry of RuCl, + K,Ru(CN), 143 and of 0~0, + K,Ru(CN), [5] mixtures at glassy carbon. Kulesza has suggested that the voltammetric procedure results in an inorganic polymer that contains 0x0 bridges [6]. The mixed valent ruthenium film was demonstrated to cause the electrocatalytic oxidation of As(II1) [4], methanol [6], and thiocyanate f7]; the mixed OS + Ru film also catalyzed the oxidation of As(II1) 151. Of special significance was that the oxidation of As(II1) at the mixed valent ruthenium film yielded a current which was limited by diffusion of the analyte in the bulk solution. Bocarsly and co-workers have also reported a procedure for immobilizing inorganic cyano-complexes [8-lo]. Oxidation of Ni electrodes in the presence of Fe(CN)z-, Ru(CN)zand Mn(CN)zyielded insoluble films which, among other characteristics, protected the Ni from corrosion. In a similar manner we prepared a film containing Ag(1) and Mo(CN);fon glassy carbon [ll]. Because it was conductive only in the presence of K+ and NH:, we were able to use it for the voltammetric determination of these non-electroactive ions.

Ruthenium Contacts Resist Chemical Attack in Communications Use

In general, sputtered ruthenium films attain platinum‐group properties that make them candidates for various uses in electrical, thermal and decorative areas. Advanced communications devices are one of these areas. Ruthenium could possibly be used as a diffusion barrier and adhesive layer, as a suicide former for low ohmic contacts, and as a final metallisation over platinum suicide for very large scale integration (VLSI) applications.

Electrocatalytic oxidation and determination of arsenic(III) on a glassy carbon electrode modified with a thin film of mixed-valent ruthenium(III, II) cyanide

Le courant de pic voltammetrique a balayage lineaire obtenu est directement proportionnel a la concentration en As(III) dans le domaine 5 μM-2 mM avec une limite de detection de 3,5 μM

Silicides of ruthenium and osmium: Thin film reactions, diffusion, nucleation, and stability

The reactions of ruthenium and osmium thin films with their silicon substrates lead to the formation of the following phases: the isomorphous Ru2Si3 and Os2Si3, and OsSi2. Ru2Si3 forms by a diffusion controlled mechanism from approximately 450 to 525 °C; the activation energy is 1.8 eV. Os2Si3 grows by the same process and with the same activation energy as Ru2Si3, but at slightly higher temperatures (for equivalent rates). OsSi2 grows at about 750 °C by a nucleation controlled mechanism. With an alloy of ruthenium containing 33 at.% rhodium, one obtains RuSi, which forms by a diffusion controlled mechanism with an activation energy of 2.4 eV from 400 to 475 °C, and Ru2Si3. In the case of the ruthenium alloy, the formation of Ru2Si3 is not diffusion controlled; the controlling process is akin to a nucleation mechanism. Ru2Si3 and Os2Si3 form by silicon motion. This is also true of OsSi2, but the high formation temperature results in some metal motion also during the formation of that phase. The diffusion processes are discussed on the basis of simple ideas about diffusion in intermetallic compounds. The nucleation processes are shown to occur for the phases OsSi2 and Ru2Si3 (with rhodium), as in other nucleated phases, when the enthalpy contribution to the driving force is close to zero. The observation leads one to anticipate that for most (perhaps all) platinum-like metals the silicides with the highest silicon content should be unstable at low temperatures.

Reflectance of evaporated ruthenium films from 300 Å to 50 μm

Reflectance of evaporated ruthenium films from 300 Å to 50 μm

Potassium-dinitrogen-ruthenium complex as an active catalyst for nitrogen fixation

Potassium uptake by metallic ruthenium is enhanced and stabilized by the presence of nitrogen, accompanying a significant nitrogen uptake. The stabilized part of potassium uptake which can not be removed by evacuation at 350 °C is in a stoichiometric relation to the nitrogen uptake, suggesting that the uptake is caused by formation of a ternary compound (KN 2Ru) n . Electric resistance of ruthenium film seems to be decreased slightly by formation of the ternary compound. The potassium adsorbed on this compound gives rise to an enhanced activity for the isotopic equilibration of dinitrogen. The dinitrogen nature of the ternary compound is supported by formation of hydrazine in addition to ammonia and a dinitrogen complex of ruthenium upon hydrolysis as well as ethanolysis.

The role of carbon in methanation by cobalt and ruthenium

The reaction of 5:1 hydrogen/carbon monoxide on carbon-13-covered, evaporated films of cobalt and ruthenium (which represented typical Fischer-Tropsch catalysts) at 250/sup 0/-300/sup 0/C and Vertical Bar3; 1 mm Hg total pressure, produced about equal amounts of labeled and unlabeled methane. The higher initial yields of labeled methane obtained on nickel were probably due to a lower degree of deactivation of adsorbed carbon-13, or possibly to methane formation via a different intermediate.

Sputtered Ruthenium as a Contact Material for Sealed Reeds

Cobalt-hardened gold is used as a contact material on remreed sealed contacts. A possible change of material for contacts of this type has been studied. The contact material investigated consists of a thin film of ruthenium over a thicker film of hardened gold. Both films are deposited by dc sputtering. The advantages of this contact finish compared to electroplated hard gold are reviewed: lower erosion per arcing operation, reduced arcing, and better resistance stability due to lower foreign element comtamination. The reliability of ruthenium contacts is related to that of hard gold contacts. A small change of contact geometry (gap and overlap) is needed to maintain the contact resistance at the level found with hard gold. The reliability is better in low-voltage (~5 V) level operation, due to the elimination of carbonaceous contaminants. The ruthenium contacts exhibit longer life in erosion tests involving cable discharges. Ruthenium contacts can be sealed off in a water free atmosphere so they could be used at below-freezing temperatures. Ruthenium contacts are able to withstand magnetostrictive scrubbing without sticking failures. However, the life of the ruthenium contact when switching current of 100mA (make and break) at 50V in a resistive load does not show significant improvement over hard gold. This is explained in terms of bridge transfer due to chattering during the make operation of the contacts.

Chlorine distribution in thermally decomposed ruthenium, iridium and platinum oxide films

Chlorine distribution in thermally decomposed ruthenium, iridium and platinum oxide films

Reflectance and optical constants of evaporated ruthenium in the vacuum ultraviolet from 300 to 2000 Å*

The reflectance and optical constants of evaporated ruthenium films were measured in the wavelength region from 300 to 2000 Å. The films were evaporated by electron bombardment in an ion-titanium-pumped vacuum system and were typically deposited at a rate of about 40 Å/s onto glass and super-polished fused-quartz substrates which were at 40 and 300 °C. Variation of deposition rate from 1 to 80 Å/s had very little effect on their reflectance. The optical constants were determined from reflectance measurements made at several angles of incidence. Reflectance losses during extended exposure to air were rather small, indicating that, if oxide films form at room temperature, they are very thin. Films made on substrates at 300°C had slightly higher reflectances than those made at 40°C. Owing to interference effects, semitransparent films 150 to 200 Å thick showed higher reflectances than opaque films at wavelengths in the region of 584 Å. At wavelengths near 2000 Å, films 300 Å thick had highest reflectances. Ruthenium films prepared under optimum conditions had reflectances of 26% at 584 Å.

Photoelectric determination of the work function of Ru-films as a function of sintering temperature (78°K–925°K)

The photoelectric work function φ and the emission constant M of clean ruthenium films evaporated on pyrex substrates at 78 °K and on non-cooled, highly outgassed quartz substrates were determined after sintering at various temperatures up to 1000°K. For films deposited on pyrex substrates and subsequently sintered φ rises from 4.52 ± 0.03 eV at 78°K to 5.02 ± 0.03 eV at 573°K. For films evaporated on quartz and annealed above 700°K, φ is 5.10 ± 0.05 eV. The emission constant M continues to decrease even beyond the temperature where φ ceases to increase. On the basis of their position in Group VIII the work function of Rh and Os films deposited at 78°K and sintered at 373°K are predicted to be 5.1–5.2 eV and 4.9–5.0 eV respectively.

Kinetics of electrodeposition and catalytic activity of thin films of ruthenium

It is shown that a single layer only, of ruthenium, is deposited electrochemically on to mercury from acid solutions of ruthenium chloride. Evidence is presented that the layer has half the thickness of unit lattice repeat in the c0 direction of the close-packed hexagonal lattice and that it is formed by the two-dimensional growth of centres, nucleated in the initial stages of electrodeposition on the substrate electrode. The electrodeposition is accompanied by catalytic hydrogen evolution and this process is restricted to the edges of the growth centres, the surface of the fully-formed film having low catalytic activity. The characteristics of the catalytic hydrogen evolution are similar to those which have been observed on bulk platinum metals; high rates of reaction may be reached at the catalytic sites.

Simple, Rapid Sputtering Apparatus

A simple sputtering apparatus that consistently deposits opaque films of nickel and the noble metals in 3 to 10 min has been made. The chamber is constructed from a standard Pyrex pipe reducer. By use of a large-diameter aluminum rod as the cathode support and a hemispherical aluminum shell as a shield for the pump orifice and base plate, the glow discharge has been confined primarily to the volume between the cathode and the work stand. The efficiency of the coating unit has thereby been increased. Films of nickel, iridium, ruthenium, and osmium formed on glass or quartz substrates were very adherent and were not readily scratched with a steel scribe.

Catalysis on evaporated metal films III. The efficiency of different metals for the reaction between ethane and deuterium

The catalyzed exchange reaction between ethane and deuterium has been studied over evaporated films of tungsten, molybdenum, tantalum, zirconium, chromium, vanadium, nickel, platinum, palladium, rhodium and ruthenium. Manganese, silver and iron films were inactive up to 370° C, but the latter produced some highly deuterated methane. Cobalt showed simultaneous cracking and exchange at 300° C and cracking was observed on nickel above 160° C. The initial distribution of the deutero-ethanes fell into three classes which are exemplified by molybdenum, palladium and chromium. With molybdenum the main product was C 2 H 5 D, with palladium C 2 D 6 , and both were major products with chromium. A theory is developed which accounts for the observed distributions in terms of the relative probability of an adsorbed ethyl radical either desorbing as ethane or adsorbing further to ethylene— the highly deuterated products being formed by repeated transitions between ethyl radical and ethylene residue. The energies of activation ranged from 7 kcal/mole for molybdenum to 21 kcal/mole for palladium, and high-frequency factors were associated with high energies of activation. The orders of reaction with respect to both gases were determined on tungsten, palladium and rhodium, and possible mechanisms are formulated. Some evidence that different crystal faces had different catalytic activities was obtained by comparing the distribution of products formed on oriented and unoriented nickel films. Nickel films showed a falling energy of activation in the temperature range 0 to 75° C, and evidence was obtained that this was due to a reversible shift in the equilibrium amounts of different adsorbed species.