Showing papers on "Tungsten published in 1980"
201 citations
180 citations
TL;DR: On Ir(110, tungsten adatoms move preferentially across [$1\overline{1}0$] channels rather than along them, as observed on other channeled planes.
Abstract: On Ir(110), tungsten adatoms move preferentially across [$1\overline{1}0$] channels rather than along them, as observed on other channeled planes. The jump mechanism underlying this anomalous behavior has been tested in an atom probe. It is found that after cross-channel motion, an iridium adatom is left on the iridium surface rather than the tungsten originally deposited. These observations provide the first experimental evidence for atomic diffusion on a metal by exchange of the adatom with an atom from the substrate.
162 citations
TL;DR: In this paper, the authors have shown that the equilibrium vacancy concentration at the melting point is Cv(Tm=3695 K) ≃ 1 × 10−4 using this value, the vacancy resistivity and formation entropy, pIV=6·3 × 10 −4 Ω cm and SIV F=2·3k respectively, were deduced.
Abstract: Resistivity and transmission-electron-microscopy investigations have been carried out on high-purity quenched tungsten These have yielded values for the monovacancy formation and migration enthalpies of HIV F=3·67±0·2 eV and HIVM=1·78 ± 01 eV respectively, Direct observations of voids formed by vacancy precipitation during quenching and subsequent annealing have led to the conclusion that the equilibrium vacancy concentration at the melting point is Cv(Tm=3695 K) ≃ 1 × 10−4 Using this value, the vacancy resistivity and formation entropy, pIV=6·3 × 10−4 Ω cm and SIV F=2·3k respectively, were deduced The results are discussed in relation to self-diffusion in tungsten and difficulties encountered in earlier work on quenched tungsten
145 citations
TL;DR: In this paper, the attachment of helium to annealed inert gas impurity atom traps in tungsten has been measured by thermal desorption spectrometry, and the first helium atom trapped was found to have approximately the same trapping radius (≈2.8 A).
126 citations
TL;DR: In this paper, the growth mode, structure, thermal stability and work function of Pd films up to several monolayers in thickness on a W{110} surface are studied.
120 citations
TL;DR: In this paper, the isomerization of 1-butene and cyclopropane and the disproportionation of propylene, propylene and ethylene were investigated over tungsten oxides supported on MgO, Al2O3, SiO2, TiO2 and ZrO2.
91 citations
80 citations
73 citations
72 citations
TL;DR: In this article, the dependence of photocurrent on laser intensity was studied up to the damage threshold of tungsten using 30 ps pulses from a Nd:YAG laser.
TL;DR: Fluid inclusion evidence from the Grey River Tungsten Prospect, Newfoundland and other tungsten deposits indicates that CO2 is an important component of the hydrothermal fluid as mentioned in this paper.
Abstract: Fluid inclusion evidence from the Grey River Tungsten Prospect, Newfoundland, and other tungsten deposits indicates that CO2 is an important component of the hydrothermal fluid. Carbon dioxide is e...
TL;DR: In this article, the formation of anodic films on tungsten has been studied in 1N solutions of H 2 PO 4, H 2 SO 4, HNO 3, HClO 4 and HCl at different temperatures.
TL;DR: The incorporation of lithium at ambient temperatures into WO 3 has been studied in this article, where the cubic phase was found to have higher lithium contents, 0.67, at 25°C than at 650°C, and 0.5, approaching the value 0.75 calculated from the crystal structure.
TL;DR: In this article, a hydrogen adsorption site bridging two metal atoms is proposed for both the low coverage, β 2, and the high coverage β 1, states of hydrogen on W(100) and the change in the symmetric metal-hydrogen stretching frequency is correlated with the reconstruction of the tungsten surface in the β 2 state.
TL;DR: In this paper, the angular differential and total sputtering yields of polycrystalline nickel and tungsten have been measured for 1 and 4 keV H+ ion bombardment at incidence angles between 0° and 80°.
Abstract: Angular differential and total sputtering yields of polycrystalline nickel and tungsten have been measured for 1 and 4 keV H+ and 4 keV He+ ion bombardment at incidence angles between 0° and 80°. The differential sputtering yields (dY/dΩ) were determined with the aid of the collector technique, whereas the total yieldY was determined from the weight loss of the target during irradiation. Asymmetric angular distributions are observed at oblique angles of incidence, the emission maximum being shifted in forward direction (with respect to the incident ions). Even more pronounced than the change in shape of the emission distribution is an increase in the differential yield:dY/dΩ rises with increasing incidence angle over the whole range of ejection angles, the increase being most prominent in the direction of primary recoil emission. This effect is therefore ascribed to emission of surface atoms in direct projectile-surface atom collisions.
TL;DR: In this paper, the kinetics of growth of anodic films have been studied in 0.01Nolutions of,,, and at room temperature, and the validity of the relationship was verified in the current density range 0.2-16 mAcm−2, nearly constant B values were found in all investigated solutions.
Abstract: The kinetics of growth of anodic films have been studied in 0.01Nsolutions of , , , and at room temperature. The validity of the relationship was verified in the current density range 0.2–16 mAcm−2, Nearly constant B values were found in all investigated solutions. A lower value of dielectric constant was measured for the anodic films grown in phosphoric acid solutions. The effect of phosphate ions incorporation on the breakdown voltage is also discussed. The hypothesis of growth in presence of high space charge is carefully considered.
TL;DR: In this article, the influence of chromium and chromium oxide films and gas compositions on plasma etching characteristics was investigated and the contour and reverse etches were shown to be anomalous with tungsten impurities.
Abstract: The influences of chromium and chromium oxide films and gas compositions on plasma etching characteristics were investigated. Oxygen as well as chlorine is found to be responsible for etching. One possible etching reaction is proposed, in which a basic reaction product is assumed to be CrO2Cl2 which will be volatile in gas plasma. The impurities such as W, Fe, and Cu contained in the film become nonvolatile compounds which accumulate on the surface of the film and form a masking layer resulting in a suppression of the reaction. Anomalous etching modes called the contour and reverse etches were found with the chromium oxide films containing tungsten impurities. The mechanism of these anomalous etching modes is discussed, in which the accumulation of the tungsten compounds on the surface of the film is a basic mechanism. The reverse etch mode was applied to the fabrication of photomasks for MOS LSI.
TL;DR: In this paper, an investigation was conducted to examine the adhesion and friction of single-crystal diamond in contact with various transition metals and the nature of metal transfer to diamond.
TL;DR: In this paper, the oxygen diffusion coefficient in growing WO 8−x has been determined for the temperature range of 568-908°C and may be expressed as: D = 6.83 × 10 −2 exp (−29,890/ RT ), with the activation energy given in cal/mole.
Patent•
31 Jul 1980
TL;DR: There are thermoplastic and thermosetting polymers which incorporate tungsten and/or molybdenum metal atoms as mentioned in this paper, and the metal atoms are incorporated into the polymer by reacting a monomer or polymer containing at least one free carboxyl group with a reaction product of Tungsten or moly bdenum and pyrrolidine.
Abstract: There are disclosed thermoplastic and thermosetting polymers which incorporate tungsten and/or molybdenum metal atoms. The metal atoms are incorporated into the polymer by reacting a monomer or polymer containing at least one free carboxyl group with a reaction product of tungsten or molybdenum and pyrrolidine.
TL;DR: In this article, the authors measured the diffusion coefficient of the saddle formed by two nearest-neighbor W atoms and showed that the barrier is 0.21 eV high and \ensuremath{\sim} 0.5 \AA{} wide.
Abstract: The diffusion coefficients of $^{1}\mathrm{H}$ and $^{2}\mathrm{H}$ on the (110) plane of W have been measured by the field-emission fluctuation method. Below 140 K $^{1}\mathrm{H}$ diffusion corresponds to pure tunneling. The barrier is shown to be 0.21 eV high and \ensuremath{\sim} 0.5 \AA{} wide, and probably corresponds to passage over the saddle formed by two nearest-neighbor W atoms. Evidence for a phase transition at 89 K (at $\ensuremath{\theta}=0.6$) is also presented.
TL;DR: In this paper, the surface diffusion of oxygen on three macroscopic crystal planes of tungsten, {110, {411} and {320), using a combined molecular beam deposition and scanning electron beam technique, was studied.
Patent•
12 Nov 1980
TL;DR: In this article, a chemical vapor deposition method for manufacturing tungsten-silicide thin-film resistors of predetermined bulk resistivity and temperature coefficient of resistance (TCR) was proposed.
Abstract: A chemical vapor deposition method for manufacturing tungsten-silicide thin-film resistors of predetermined bulk resistivity and temperature coefficient of resistance (TCR). Gaseous compounds of tungsten and silicon are decomposed on a hot substrate to deposit a thin-film of tungsten-silicide. The TCR of the film is determined by the crystallinity of the grain structure, which is controlled by the temperature of deposition and the tungsten to silicon ratio. The bulk resistivity is determined by the tungsten to silicon ratio. Manipulation of the fabrication parameters allows for sensitive control of the properties of the resistor.