Showing papers on "Bismuth published in 1988"
TL;DR: In this article, the electrochemical behavior of a bismuth surface compound formed spontaneously without applying external potential when platinum is put in contact with a solution of a Bi(III) salt was studied.
253 citations
173 citations
Patent•
29 Sep 1988
TL;DR: In this paper, a reaction system and process for uniformly heating semiconductor substrates and a device for supporting the same and direct conductive heating of IC wafers within a reactor are described.
Abstract: A reaction system and process for uniformly heating semiconductor substrates and a device for supporting the same and direct conductive heating of IC wafers within a reactor are described. The substrate is held in direct contact with the heating source positioned within the reactor. The heat source is a thermal delivery module made of material such as solid silicon carbide, or high temperature material containing resistive heating elements. The heat is uniformly transferred to the walls of the module by a molten metal having a low melting point and high boiling point such as essentially indium or bismuth or a eutectic or indium and bismuth.
117 citations
TL;DR: In this article, superconducting films of CaF2, SrF2 and BiO3 oxides were characterized by four-probe resistivity measurements, Rutherford backscattering, transmission electron microscopy, x-ray diffraction, and Hall measurements.
Abstract: Superconducting films of Ca‐Sr‐Bi‐Cu oxides have been prepared by coevaporation of CaF2, SrF2, Bi, and Cu, followed by post‐oxidation in wet O2. The films were characterized by four‐probe resistivity measurements, Rutherford backscattering, transmission electron microscopy, x‐ray diffraction, and Hall measurements. Zero resistance was achieved at ∼80 K, although evidence of traces of superconductivity at higher temperatures was seen in resistivity and Hall data. The critical current at 4.2 K was 1.0×106 A cm−2. The films were epitaxial on 〈100〉 and 〈110〉 SrTiO3 substrates. The electrical and structural properties of the films were insensitive to film composition over a wide range of stoichiometries.
71 citations
TL;DR: In this paper, the crystal structure of the high-Tc Bi2-x(Ca, Sr)3Cu2+xO9-y with x = 0.2 and y=0.78 was studied by means of neutron and X-ray powder diffraction.
Abstract: The crystal structure of the high-Tc Bi2-x(Ca, Sr)3Cu2+xO9-y with x=0.2 and y=0.78 was studied by means of neutron and X-ray powder diffraction. Since the unit cell parameters were relatively large for powder diffraction analysis, an averaged structure was refined, assuming an orthorhombic sub-cell (a=5.39 A, b=5.39 A and c=30.37 A) which corresponds to 1/5 of the unit cell: This is a derivative of Bi4Ti3O12. The double perovskite unit interleaved by the double bismuth layers is B-type, i.e. a CuO6 octahedron is surrounded by eight alkaline earth metal ions. The pyramidal CuO5 configuration is found in this oxide. The copper valency is estimated at about 2.3 on the basis of the determined chemical composition.
67 citations
Patent•
05 Jan 1988
TL;DR: A lead-free solder composition of approximately 90% to 95% by weight tin, approximately 3% to 5% antimony, approximately 1% to 4.5% bismuth, and approximately 0.1% to 0.5%.
Abstract: A lead-free solder composition of approximately 90% to 95% by weight tin, approximately 3% to 5% by weight antimony, approximately 1% to 4.5% by weight bismuth, and approximately 0.1% to 0.5% by weight silver.
65 citations
TL;DR: In this article, the chemical composition and the crystal structure of the Bi-Ca-Sr-Cu-O oxide with a high Tc of about 75 K have been studied by the combined techniques of crystal structure imaging and spectroscopic microanalysis using a 400 kV high-resolution analytical electron microscope.
Abstract: The chemical composition and the crystal structure of the Bi-Ca-Sr-Cu-O oxide with a high-Tc of about 75 K have been studied by the combined techniques of crystal structure imaging and spectroscopic microanalysis using a 400 kV high-resolution analytical electron microscope. The crystal is orthorhombic with lattice parameters a=0.54 nm, b=2.70 nm and c=3.06 nm. The chemical composition is assigned as Bi2CaxSrzCu2Oy, where x and z are approximately 1.0 and 1.5, respectively. The structure image reveals that the structure is comprised of a bismuth oxide layer interleaved with an oxygen deficient perovskite-like layer. It is suggested that a nearly commensurate superstructure based on the perovskite-type structure is formed.
61 citations
TL;DR: In this paper, neutral and singly charged anion or cation clusters of antimony and bismuth are produced by laser vaporization in a pulsed nozzle cluster source.
Abstract: Neutral and singly charged anion or cation clusters of antimony and bismuth are produced by laser vaporization in a pulsed nozzle cluster source. Neutral clusters are photoionized near threshold with a fluorine excimer laser, while ionized clusters are sampled directly from the laser vaporization plasma. All species are mass analyzed with a time‐of‐flight spectrometer. Abundance patterns in these systems exhibit ‘‘magic numbers’’ that are strikingly charge dependent. Compared at the same charge, corresponding neutral and cation spectra of these metals are quite similar, but significant differences arise in the two anion cluster distributions. Neutral cluster growth in these systems ends abruptly at five atoms while the ionized distributions fall off gradually out to beyond 12–15 atoms. These unique patterns are examined in the context of cluster growth dynamics and suspected cluster stability based on the predictions of simple electron counting models.
61 citations
TL;DR: In this article, mass spectral abundances were interpreted to reflect cation stability patterns, and branching ratios were consistent with the production of stable neutral and cation molecular fragments, suggesting a statistical dissociation mechanism.
Abstract: Antimony and bismuth cluster cations are produced by laser vaporization in a pulsed nozzle source and probed with mass spectroscopy and mass selected photofragmentation at 248 nm. Mass spectral abundances are interpreted to reflect cation stability patterns. Fragmentation products and branching ratios are consistent with the production of stable neutral and cation molecular fragments, suggesting a statistical dissociation mechanism.
58 citations
TL;DR: A gas sensor that operates by the detection of changes in the bulk conductivity of a bismuth molybdate semiconductor catalyst is presented in this paper, where the reduction of the catalyst by organic vapours produces highly mobile oxygen vacancies, which have a direct effect on the carrier density throughout the sample.
57 citations
TL;DR: In this paper, a superconducting film of bismuth strontium calcium copper oxides was prepared by chemical vapor deposition at 910?C and 1 Torr on a MgO substrate using a Bismuth alkoxide and?-diketonate chelates of Sr, Ca and Cu as source materials.
Abstract: Superconducting films of bismuth strontium calcium copper oxides were prepared by chemical vapor deposition at 910?C and 1 Torr on MgO substrate using a bismuth alkoxide and ?-diketonate chelates of Sr, Ca and Cu as source materials. In the film with Tc(zero) of 78 K, the predominant phase was Bi2(Sr, Ca)3Cu2Ox with the c-axis perpendicular to the substrate.
TL;DR: In this article, the formation of ABiNb 2 O 7 compositions in layered perovskite structure in preference to pyrochlore structure is discussed, and the protonated oxides exhibit proton conductivity in the range 10 −6 ohm −1 cm −1 at room temperature.
TL;DR: The microstructure and crystal structure of bismuth oxide phases of as-sintered and additionally heat-treated ZnO varistor ceramics was examined by means of transmission electron microscopy and X-ray powder diffraction as mentioned in this paper.
Abstract: The microstructure and crystal structure of bismuth oxide phases of as-sintered and additionally heat-treated ZnO varistor ceramics was examined by means of transmission electron microscopy and X-ray powder diffraction. Grains of β-Bi2O3 present in as-sintered samples were found to consist of two types of domains which have the same basic tetragonal lattice. They can, however, be distinguished by the contrast between local strain centers due to microdefects present in one domain. Some multiple-grain junctions contained both α- and β-Bi2O3 grains. Heat treatment induces a transformation of the α- and β-Bi2O3 phases into γ-Bi2O3. A clear crystallographic relationship between the transforming phases β to γ is shown. The β-Bi2O3 phase was also found to transform into the non-stoichiometric crystalline Bi2O2.33 phase.
TL;DR: In this article, the authors reported the successful synthesis of an oxide compound of Bi and Fe with the garnet structure, albeit under certain restricted conditions, under the assumption that the bismuth-iron garnet is not found naturally.
Abstract: Since an anomalously large Faraday rotation ({theta}F) for BiCa{sub 2}Fe{sub 4}VO{sub 12} was reported in 1969, bismuth-iron garnets have attracted attention as high-performance magnetooptical materials. Since the magnitude of the magnetooptical effect is proportional to the Bi content, there is much interest in heavy bismuth substitution. However, completely substituted Bi{sub 3}Fe{sub 5}O{sub 12} is not found naturally, nor has it every been successfully synthesized. Here, the authors report on the successful synthesis of an oxide compound of Bi and Fe with the garnet structure, albeit under certain restricted conditions.
TL;DR: In this article, high-resolution images of a new high-Tc superconductor based on the Bi-Ca-Sr-Cu-O system (Tc above 70 K) indicated a structure derived from the Bi4Ti3O12 type in which doubled bismuth oxide layers alternate with double perovskite layers along the c-axis.
Abstract: Observed high-resolution images of a new high-Tc superconductor based on the Bi-Ca-Sr-Cu-O system (Tc above 70 K) indicated a structure derived from the Bi4Ti3O12 type in which doubled bismuth oxide layers alternate with double perovskite layers along the c-axis. The orthorhombic unit cell dimensions showed an approximate relation of a=√2ap, b=5√2ap and c=8ap, where ap=3.82 A, the cell parameter of a cubic perovskite. At least a quarter of the oxygen should be deleted in accordance with the average copper valence of less than 3 and two-dimensional Cu-O layers are supposed to be responsible for the high-Tc superconductivity.
Patent•
16 May 1988
TL;DR: In this paper, high yields of unsaturated nitriles are obtained by the oxidation of olefin-ammonia mixtures in the presence of a catalyst comprising the oxides of bismuth, molybdenum, iron and at least one element of the Group II B metals as essential components.
Abstract: High yields of unsaturated nitriles are obtained by the oxidation of olefin-ammonia mixtures in the presence of a catalyst comprising the oxides of bismuth, molybdenum, iron and at least one element of the Group II B metals as essential components, and optionally the oxides of cobalt, nickel, phosphorus, arsenic and an alkali metal.
TL;DR: In this paper, two different BCSCO-containing phases have been identified in the thin films: one with a tetragonal pseudo-body-centered subcell, c=24.4 A, which is not superconducting above 28 K, and a second with c=30.6 A which is responsible for the superconductivity.
Abstract: Reactive ion beam deposition has been used to grow c‐axis‐oriented superconducting thin films in the Bi‐Ca‐Sr‐Cu‐O (BCSCO) system around the cation ratio 1:1:1:1 on single‐crystal (001) MgO. The films show a single superconducting transition with an initial onset near 85 K and a critical current of 5×104 A/cm2 at 10 K. Two different BCSCO‐containing phases have been identified in the thin films: one with a tetragonal pseudo‐body‐centered subcell, c=24.4 A, which is not superconducting above 28 K, and a second with c=30.6 A, which is responsible for the superconductivity. Electron diffraction measurements on the 30.6 A phase are consistent with those previously reported for the bulk ceramic.
TL;DR: In this paper, the authors present an ab initio calculation of the bismuth band structure, using non-local pseudo-potentials, and including the spin-orbit interaction.
Abstract: Bismuth, the heaviest group V semimetal, exhibit strong spin-orbit coupling effects. In the framework of the density functional formalism, the authors present an ab initio calculation of the bismuth band structure, using non-local pseudo-potentials, and including the spin-orbit interaction. The absence of this contribution leads to unrealistic overlaps between the bands close to the Fermi level, while correctly accounting for spin-orbit allows the experimental bismuth Fermi surface results to be reproduced. First-principles calculation of several lattice parameters and elastic constants are also reported.
TL;DR: The first growth of superconducting Bi-Sr-Ca-Cu-O films by organometallic chemical vapor deposition was described in this article, where Triphenyl bismuth and beta-diketonates of strontium, calcium, and copper were decomposed thermally at 500°C on MgO substrates in an oxygen-rich atmosphere to produce fine grained or amorphous, dark brown to black films.
TL;DR: In this paper, it was demonstrated that time resolved laser spectroscopy can give atomic lifetime data with an accuracy of better than 0.5% using a single-photon counting delayed coincidence technique, using a mode-locked dye laser for excitation.
Abstract: It is demonstrated that time resolved laser spectroscopy can give atomic lifetime data with an accuracy of better than 0.5%. This is achieved by a single-photon counting delayed coincidence technique, using a mode-locked dye laser for the excitation. Natural radiative lifetimes are measured for the sodium and bismuth atoms.
TL;DR: In this paper, high-quality X-ray absorption data have been recorded for three bismuth molybdate phases with the general composition Bi/sub 2/O/sub 3/ x nMoO/Sub 3/, for n = 3 (..cap alpha..-phase) n = 2 (..beta..)-phase), and n = 1 (..gamma..-position).
Abstract: By use of synchrotron radiation, high-quality X-ray absorption data have been recorded for three bismuth molybdate phases with the general composition Bi/sub 2/O/sub 3/ x nMoO/sub 3/, for n = 3 (..cap alpha..-phase) n = 2 (..beta..-phase), and n = 1 (..gamma..-phase). The results of these bismuth L/sub 3/-edge and molybdenum K-edge X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) studies provide structural insights about the local environments of the Bi/sup 3 +/ and Mo/sup 6 +/ ions. Also, the structure of ..beta..-Bi/sub 2/O/sub 3/ x 2MoO/sub 3/ was investigated by the use of time-of-flight powder neutron diffraction. The profile analysis of the neutron data for ..beta..-bismuth molybdate (monoclinic, P2/sub 1//n, a = 11.9515 (4) A, b = 10.7993 (4) A, c = 11.8805 (4) A, ..beta.. = 90.142 (5)/sup 0/, and Z = 8) revealed that the bismuth and molybdenum cations are present in a fluorite-like sublattice.
TL;DR: In this paper, a single crystal of the electro-optic material bismuth silicate and its isomorph Bismuth germanate, has been grown with the Czochralski technique as a function of rotation rate.
Patent•
04 Apr 1988
TL;DR: In this article, a unique hardenable silver alloy is provided which is solution annealed and preferably age-hardened to yield a silver alloy of exceptional and reversible hardness, which utilizes intermetallic systems comprising; silver, copper, combined with lithium alone or tin alone in varying percent amounts, or silver, coppersmith, lithium and either tin or antimony, or copper, lithium, tin, bismuth and antimony.
Abstract: A unique hardenable silver alloy is provided which is solution annealed and preferably age-hardened to yield a silver alloy of exceptional and reversible hardness. The alloys utilize intermetallic systems comprising; silver, copper, combined with lithium alone or tin alone in varying percent amounts, or silver, copper, lithium and either tin or antimony, or silver, copper, lithium and either aluminum or indium or zinc, or silver, copper, antimony and either aluminum or indium or zinc, or silver, copper, lithium, tin and antimony, or silver, copper, lithium, tin and bismuth, or silver, copper, lithium, tin, bismuth and antimony.
TL;DR: The transformation of high resistivity amorphous Bi1.5 SrCaCu2 Ox to superconductive material has been characterized by structural, thermochemical, transport, and magnetic measurements.
Abstract: The transformation of high‐resistivity amorphous Bi1.5 SrCaCu2 Ox to superconductive material has been characterized by structural, thermochemical, transport, and magnetic measurements. X‐ray powder diffraction confirmed that rapid solidification of Bi‐Sr‐Ca‐Cu‐O melts yields amorphous materials. Differential scanning calorimetry indicated an exothermic crystallization peak at ∼455 °C with a corresponding enthalpy of ∼50 J/g. Thermal cycling of the insulating glass to a temperature above that required for crystallization results in a transformation from an insulating to a partially superconducting material with an onset temperature of 85 K.
TL;DR: This simple, rapid, sensitive, reliable, and economical assay for bismuth in plasma, erythrocytes, and urine is based on atomic absorption spectrophotometry with hydride generation, which eliminates the problem of foaming.
Abstract: This simple, rapid, sensitive, reliable, and economical assay for bismuth in plasma, erythrocytes, and urine is based on atomic absorption spectrophotometry with hydride generation. Acid digestion eliminates the problem of foaming, which hitherto has complicated such assay of bismuth in plasma and erythrocytes. The detection limit of the assay has been improved to 0.1 micrograms/L, as compared with a previously documented limit of 2.5 micrograms/L. Average recovery exceeded 95% in all biological fluids. Economy of use derives from elimination of need for electrodeless discharge lamps and atomic absorption grade borohydride. Determination of basal concentrations of bismuth in clinical samples of body fluids gave reference intervals of 0.1-3.5 micrograms/L for plasma, 0.3-4.6 micrograms/L for urine.
TL;DR: Etude par spectrometrie Auger, par diffraction electronique et par HREEL de la coadsorption de l'ethylene et du bismuth sur le platine as discussed by the authors.
Abstract: Etude par spectrometrie Auger, par diffraction electronique et par spectrometrie HREEL de la coadsorption de l'ethylene et du bismuth sur le platine
TL;DR: In this paper, a method for the identification and quantitative analysis of reactive adsorbed molecular intermediates in surface reactions is described, and the first examples of its application is presented.
Abstract: A new method which should have relatively general applicability for the identification and quantitative analysis of reactive adsorbed molecular intermediates in surface reactions will be described, and the first examples of its application will be presented. When a reactive intermediate is generated on a surface, it often has a tendency to dissociate before desorbing. Since dissociation generally requires additional free sites on the surface, dissociation can be suppressed and desorption correspondingly enhanced if the free sites on the surface can be properly poisoned. We have found that bismuth adatoms are very good inert site blockers, which can be postdosed to the surface of a transition metal containing a reactive adsorbed hydrocarbon without destroying the hydrocarbon. Whereas in the absence of bismuth, the hydrocarbon would completely dehydrogenate during thermal desorption spectroscopy (TDS) and liberate only H2 into the gas phase, after bismuth postdosing the reactive hydrocarbon desorbs intact f...
01 Jan 1988
TL;DR: A new Bi heterocycle, which is of potential interest in terms of stability and solution behaviour, was shown to exist as an intermediate under the conditions in the mass spectrometer.
Abstract: The chemical aspects of organometallic bismuth(Ill) compounds are discussed with respect to the stability of the metal-carbon σ bond, their low dipole moments, and the limited solubility of these complexes in hydrophilic solvents. A new Bi heterocycle, which is of potential interest in terms of stability and solution behaviour, was shown to exist as an intermediate under the conditions in the mass spectrometer.