Showing papers on "Bismuth published in 1984"

Grain orientation effects on electrical properties of bismuth layer‐structured ferroelectric Pb(1−x)(NaCe)x/2 Bi4Ti4O15 solid solution

Abstract: Electrical properties, such as dielectric, resistive, ferroelectric, and piezoelectric properties, of bismuth layer‐structured ferroelectrics (BLSF) are studied on grain orientation prepared by the hot‐forging (H.F.) method. The BLSF compound which can stand the high temperature poling process is Pb(1−x) (NaCe)x/2 Bi4Ti4O15 (PNC‐100x) consisting of PbBi4Ti4O15 modified by partial substitution of (NaCe)1/2 for Pb. The effects of the solid solution introduced on piezoelectric properties are mentioned. The piezoelectrically activated PNC solid solution has a larger value of electromechanical coupling factors kt and k33 than those of nonmodified samples. The grain orientation makes the piezoelectric properties of BLSF ceramics much more pronounced than those of the nonoriented ceramics. Coupling factor k33 along with piezoelectric constants d33 and g33 of H.F. PNC ceramics are enhanced and their anisotropies in k33/k31, d33/d31, and g33/g31 are emphasized.

Enthalpies of formation of liquid and solid binary alloys of lead, antimony and bismuth with rare earth elements

Abstract: The predictions of Miedema's model for the heats of formation of binary intermetallic compounds of lead, bismuth and antimony with rare earth elements and for the heats of mixing and solution of the corresponding liquid alloy systems are presented. The predicted values are compared with the existing experimental data. The differences between the experimental and the calculated values of the enthalpy are discussed.

Recent advances of bismuth garnet materials research for bubble and magneto-optical applications

Abstract: Epitaxially grown bismuth-substituted iron garnet films of composition R 3-x Bi x Fe 5-y M y O 12 with x \leq 2.5 (R=Y,Gd,Lu,Yb and M = Al,Ga,Si) are considered with respect to the temperature and concentration dependence of their magnetic and magneto-optical properties. In particular, the magnetization, Curie temperature, uniaxial anisotropy, optical absorption and Faraday rotation reveal pronounced changes with increasing bismuth content. Special attention is paid to the control of the uniaxial growth-induced anisotropy caused by the ordering of the bismuth ions via the site preference mechanism. This ordering process is characterized by a strong dependence on the growth conditions such as the melt composition and the supercooling allowing the variation of K\min{u}\max{g} in the range O Jm-3. The magneto-optical properties exhibit a linear increase with increasing bismuth content.

An analytical electron microscope study of the kinetics of the equilibrium segregation of bismuth in copper

Abstract: The detection and quantification of the segregation of Bi to grain boundaries in Cu using Analytical Electron Microscopy is demonstrated and the effects of time and temperature are observed. The experimental data are compared with the theoretical prediction of McLean’s segregation isotherm. Special grain boundaries are also considered. The analysis shows that the detection of the variation of segregation with time and temperature as well as grain boundary characteristics is possible using analytical electron microscopy and that the quantification techniques used here agree well with theoretical calculations of the segregant levels.

Potentiometric stripping analysis with a thin-film gold electrode for determination of copper, bismuth, antimony, and lead

Abstract: The in situ thin-film gold electrode at glassy carbon substrate has been successfully used as a working electrode in potentiometric stripping analysis. Gold(III) present in the solution studied also serves as an oxidant. The equations for the transition time (stripping signal) and for the stripping curve of potentiometric stripping analysis have been derived and verified experimentally for copper(II), bismuth(III), antimony(III), and lead(II), in 0.1 M HCl. This method is available for the simultaneous determination of these four ions used for sample analysis.

Measurement of the Refractive Index and Optical Absorption Spectra of Epitaxial Bismuth Substituted Yttrium Iron Garnet Films at uv to Near-ir Wavelengths

Abstract: Refractive-index and optical-absorption spectra of Bi-substituted yttrium iron garnet films, epitaxially grown by liquid-phase epitaxy, have been measured in the spectral regime 0.26 μm≦λ≦1.9 μm by thin-film interference for λ ≳0.52 μm and by ellipsometry forλ≲0.52 μm. The Y3−x−yBixPbyFe5−zPtzO12 films contain bismuth in the range O≦x ≦1.42, lead in the range 0.01 ≦y≦0.08 and platinum in the range 0.005<=z≦0.03. There is satisfactory coincidence between the results from ellipsometry and thin-film interference in the overlapping wavelength region. The materials investigated are the same as reported earlier from this laboratory in ter mof their magnetic and magnetooptic properties.

Distribution of silver in massive sulfide ores

Abstract: The distribution of silver in connection with the formation of massive sulfide ores is discussed. It is proposed: 1) The affinity between silver and galena-rich ores is only pronounced if antimony and/or bismuth are also present in significant amounts, and 2) The degree of correlation between silver and lead is partly a function of the Ag/Sb+Bi ratio in the ore and increasing with decrease in ratio at least up to Ag/Sb+Bi=1. Observations of correlated Cu/Ag ratios in complex ores indicate that some silver was solved in chalcopyrite at the time of deposition. This is often masked by the much higher silver contents associated with galena. The Bi/Sb ratio is expected to increase downwards stratigraphically in galena-rich ores, due to a larger solubility of silver-bismuth in galena as compared with silver-antimony, at a realistic deposition temperature (200–300 °C). However, such an effect will only rarely be seen, due to incomplete separation of the ore-constituents at the time of deposition, as well as to post-depositional changes.

Method for purification of sulfuric acid solution

Abstract: A method for purification of a sulfuric acid solution such as, for example, a copper electrolyte which entrains at least one metal ion species selected from the group consisting of antimony ions, bismuth ions, and iron ions and having a sulfuric acid concentration of at least 50 g/liter is disclosed. The method comprises exposing the sulfuric acid solution to a chelating resin possessing aminomethylenephosphonic acid group as a chelate forming group thereby effecting adsorptive separation of the aforementioned at least one metal ion species from the solution. By the method described above, the antimony ions, bismuth ions, and/or iron ions contained as impurities in the copper electrolyte can be easily and efficiently separated out of the system without entailing any ecological problem.

Bismuth-substituted iron garnet films prepared by RF diode sputtering

Abstract: Single-phase, magnetically uniaxial Gd 3-x Bi x Fe 5-y Al y O 12 films have been prepared by RF diode sputtering with RF substrate bias on single-crystal (Gd,Ca,Mg) 3 (Ga,Zr) 5 O 12 and amorphous substrates. Epitaxial growth is observed by annealing of amorphous films for lattice misfits <0.03A (tensile stress). Intrinsic properties, such as lattice constant, saturation magnetization, and polar magnetooptic effects, compare well with liquid-phase epitaxial films of equal composition. Film imperfections originating from particles expelled from the ceramic targets cause some optical loss, increased coercivity and increased linewidth in X-ray diffraction.

Determination of arsenic, antimony, bismuth, cadmium, copper, lead, molybdenum, silver and zinc in geological materials by atomic-absorption spectrometry

Abstract: Arsenic, antimony, bismuth, cadmium, copper, lead, molybdenum, silver and zinc are very useful elements in geochemical exploration. In the proposed method, geological samples are fused with potassium pyrosulphate and the fusate is dissolved in a solution of hydrochloric acid, ascorbic acid and potassium iodide. When this solution is shaken with a 10%V/V Aliquat 336-isobutyl methyl ketone organic phase, the nine elements of interest are selectively partitioned in the organic phase. All nine elements can then be determined in the organic phase using flame atomic-absorption spectrometry. The method is rapid and allows the determination of Ag and Cd at levels down to 0.1 p.p.m., Cu, Mo, and Zn down to 0.5 p.p.m., Pb, Bi and Sb down to 1 p.p.m. and As down to 5 p.p.m. in geological materials.

Superconductive material of oxide and manufacture thereof

Abstract: PURPOSE:To obtain a high critical temperature by using a composite oxide composed of barium, bismuth, and oxygen and expressed by a specific chemical formula. CONSTITUTION:After uniform mixing of a Ba compound with a Bi compound or a Ba compound with an A compound [where, A is Sr, Pb, Sc, Y, or a lanthanum group element; the atomic ratio of Ba to A: A/(Ba+A) is 0.5 or less] and a Bi compound, the powder obtained by calcination at a temperature of 600 deg.C or more is molded by pressing in an oxidizing atmosphere, and next a large amount of oxygen defect produced at the step of calcination is repaired by firing at 700 deg.C or more under a pressure of 10kg/cm or more of oxygen or 10kg/cm or more of partial pressure of oxygen, thereby forming BaBiO3-delta (0<=delta<0.5) or a material with the Ba in this chemical formula replaced with Sr, Pb, Sc, Y, or a lanthanum group element within a range of 50atm% or less. This manner enables the production of the titled material having a superconductive transfer temperature TC of approx. 12K.

Kinetic study of the partial oxidation of propene and 2-methylpropene on different phases of bismuth molybdate and on a bismuth iron molybdate phase

Abstract: Kinetic studies of the partial oxidation of propene to acrylaldehyde and 2-methylpropene to methacrylaldehyde have been carried out on various bismuth molybdates [Bi2Mo3O12(α), Bi2Mo2O9(α+γ or β) and Bi2MoO6(γ)] and Bi3FeMo2O12(phase X). The partial pressures of O2 and alkene have been varied and a maximum in the yield of aldehyde has been observed for a value of the alkene pressure which depends on the sample. In contrast, no maximum has been observed for carbon dioxide. A simple mechanistic model has been proposed involving as a first step the rapid adsorption of the alkene. This is followed by the rate-determining step, the formation of a π-allyl intermediate with a surface site S; the methacrylaldehyde is then formed relatively fast. Next 2-methylpropene reacts with site S to give an oxygenated hydrocarbon species which is strongly adsorbed and which blocks the site active for aldehyde formation. Finally the blocking hydrocarbon is oxidized into CO2, liberating the active surface sites. The model fits the experimental data well and allows one to differentiate different catalysts by the rate constant of step (1): the rate constants of the other steps are approximately equal. The study clearly shows that a comparison between catalyst performances is misleading, particularly for 2-methylpropene oxidation, under the same experimental conditions, since the relative ordering depends on the pressure of alkene with respect to that of oxygen. Carbon dioxide does not result from a total oxidation of the aldehyde under our conditions of low conversion levels. The initial activity for aldehyde formation is much higher in the case of 2-methylpropene than for propene and follows the order X α+γ > α > γ > β. The alkane adsorption equilibrium may play the major role in catalytic activity.

Thermal shock resistant thermoelectric material

Abstract: A thermoelectric material comprising an alloy, a solid solution or an alloy and a solid solution consisting essentially of (a) iron disilicide, (b) 0.3 to 4.6 atomic %, based on the total amount of the whole component elements, of boron and optionally, (c) 0.1 to 5.0 atomic %, based on the total amount of the whole component elements, of one element or more selected from the group of zinc, cadmium and mercury of Group IIB, aluminum, gallium, indium and thallium of Group IIIB, phosphorus, arsenic, antimony and bismuth of Group VB, sulfur, selenium and tellurium of Group VIB, chromium, molybdenum and tungsten of Group VIA, manganese, technetium and rhenium of Group VIIA and cobalt, nickel, rhodium, palladium, iridium and platinum of Group VIII in the periodic table of elements.

Equilibria between silica-saturated iron silicate slags and molten Cu-As, Cu-Sb, and Cu-Bi Alloys

Abstract: The solubilities of copper, arsenic, antimony, and bismuth in silica-saturated iron silicate slag, equilibrated with molten copper which included the corresponding element, were measured at temperatures 1473 and 1523 K under oxygen pressures ranging from 10−1 to 10−7 atm. The results confirm that copper is dissolved as CuO0.5 in silica-saturated fayalite slag. Dissolution of As, Sb, and Bi was found to be dependent upon the oxygen potential, suggesting oxidic rather than atomic dissolution. The data obtained also support models in which these elements exist in the slag mainly as two different types of oxides, but occasionally these oxides coexist with neutral atoms. Based on these models, equations were obtained that related the solubilities of these elements in the slags to the oxygen potential in them. The knowledge obtained in this investigation will be helpful in eliminating deleterious minor elements in copper smelting.

Hall effect in bismuth in quantizing magnetic fields

Abstract: The Hall effect has been investigated in the very low-temperature limit in bismuth, when the lattice scattering is dominant in solids. The energy band structure of bismuth carriers is assumed to follow the modified nonellipsoidal, nonparabolic (MNENP) model. Results show that the Hall coefficient and Hall angle oscillate with the dc magnetic field, and the period and amplitude of the oscillations increase with the dc magnetic field. We also compare our numerical results with those found using other types of energy bands.

Bismuth bronze from machu picchu, peru.

Abstract: The decorative bronze handle of a tumi excavated at the Inca city of Machu Picchu, Peru, contains 18 percent bismuth and appears to be the first known example of the use of bismuth with tin to make bronze. The alloy is not embrittled by the bismuth because the bismuth-rich constituent does not penetrate the grain boundaries of the matrix phase. The use of bismuth facilitates the duplex casting process by which the tumi was made and forms an alloy of unusual color.

A method for processing copper smelting materials and the like containing high percentages of arsenic and/or antimony

Abstract: The invention relates to a method for preparing a sulphidic concentrate which is intended for further processing to copper and/or precious metals and which contains high percentages of arsenic and/or antimony, and possibly also bismuth in quantities likely to disturb subsequent processing stages, by partially roasting the concentrate in a fluidized bed, so as to eliminate substantially all the arsenic present and a major part of the antimony and/or bismuth. According to the invention, the concentrate and gas are supplied to a fluidized-bed reactor, and are there heated to a minimum temperature above the splitting or decomposition temperatures of the complex minerals containing arsenic and/or antimony and bismuth present in the concentrate. The oxygen potential in the reactor is regulated, so as to prevent the formation of non-volatile compounds of said impurities. The residence time of the concentrate in the reactor is controlled in a manner to ensure a given minimum elimination of the impurities. The gas and solids are withdrawn from the reactor and passed to a separating means, in which substantially impurity-free solids can be separated from the gas. The aforesaid minimum temperature and said regulated oxygen potential are maintained while the solids are in contact with said gas, and at least a part of the separated solids is returned to the reactor, for controlling the residence time, and an end product is removed from the fluidized bed and/or the separating means. The method is suitably carried out in one stage in a fluidized-bed reactor having a circulatory fluidized bed, although in certain cases the method can be carried out in two stages, in mutually separate reactors.

Method of making a compound

Abstract: This specification is directed to a method of making a compound selected from the group consisting of birnessite compounds of the formula Bix Mny O2y+1.5x.zH2 O, wherein the y/x ratio is in a range of from about 7 to about 18 and the z/y ratio is in a range of from about 0.5 to about 0.6, Pbx Mny O2y+x.zH2 O, wherein the y/x ratio is in a range of from about 6 to about 10 and the z/y ratio is in a range of from about 0.5 to about 0.6, and manganese oxide compounds containing both of these compounds. The method is characterized by the following steps. A solution is formed by mixing Mn(NO3)2 with a nitrate of bismuth or lead or mixtures thereof. The solution is maintained at a relatively constant temperature and NaOH is added to the solution, whereby Mn(OH)2 and a hydroxide of bismuth or lead or mixtures thereof form a suspension. While the suspension is being agitated, oxygen is passed through the suspension, whereby the Mn(OH)2 and the hydroxide of bismuth or lead or mixtures thereof can react to form a compound. The suspension is filtered to recover the birnessite compound. Thereafter, the compound is washed with water and dried.

Reductive Extraction of Lanthanide and Actinide Elements from Molten LiF-BeF2 Salt into Liquid Bismuth

Abstract: The equilibrium distributions of several lanthanide and actinide elements between molten LiF-BeF2 salt and liquid bismuth were determined over a wide range of salt composition at some temperatures from 600 to 800°C. The distribution behavior of each element was apparently affected by salt composition and temperature. The effect of salt composition on the distribution behavior was well explained by considering the formation of complex in the salt phase. Also, the excess free energies of the solutes in the bismuth phase, calculated from the equilibrium distribution data, were considerably negative, which suggests the formation of intermetallic compound in the bismuth phase. Taking into account the formation of these compounds, the equilibrium distribution can be expressed as

Vacuum refining copper melts to remove bismuth, arsenic, and antimony

Abstract: Experiments were carried out on 35 kg melts of doped cathode copper and anode copper in a 3 m3, 150 kW vacuum induction furnace. Rates of removal of bismuth, arsenic, and antimony were measured over temperature and pressure ranges of 1450 to 1610 K and 3 to 30 pascals, respectively. Bismuth removal was found to be rapid: 1 to 18 x 10-5 m/s. Arsenic and antimony removal were quite slow: 0.2 to 3 x 10-5 and 0.1 x 10-5 m/s, respectively, and evaporation controlled rates of refining. It is shown that, at typical concentrations of these elements in copper, monatomic evaporation is the predominant evaporation mechanism. An expression for the melt phase mass transport rate coefficient is developed from Machlin’s model. In this expression, melt diffusion is a function of melt temperature, and melt surface velocity is a function of the square root of melt surface area to volume ratio and the square of melt temperature, i.e.: it = 1.11 x 10-7[(A/V)/]1/4Tr1/2 exp(-2515/T). This coefficient is used to examine rate control in previous small scale studies and in the present and previous pilot scale studies. The gas phase mass transport coefficient is found to be proportional to the overpressure ratio defined as: total initial melt vapor pressure/chamber pressure, and is also found to be dependent on the geometry of the gas space immediately above the melt.