Showing papers on "Antimony published in 1989"
TL;DR: In this paper, computer models of these processes with a Broadlands-type geothermal water are presented in a three-part study: boiling, gas phase metal transport, and acid reactions with metal-bearing waters.
Abstract: Boiling and acidification of hydrothermal solutions are important mechanisms that lead to the deposition of base, precious, and volatile metals in epithermal systems. Computer models of these processes with a Broadlands-type geothermal water are presented in a three-part study: boiling, gas phase metal transport, and acid reactions with metal-bearing waters. Revised and partly rederived thermodynamic data necessary for such a study are presented as an appendix.Boiling of a Broadlands-type water along alternative P-T-enthalpy paths induces the precipitation of base metal sulfides, sulfosalts, and electrum. The precipitation of base metals results from the pH increase due to CO 2 degassing, and the precipitation of electrum results from the pH increase as well as sulfide loss to the gas phase. Heat transfer to or from wall rocks controls the amount of boiling; thus, because the extent of boiling controls pH, heat transfer controls the precipitated mineral assemblage.Oxyacids and hydroxides are generally the dominant aqueous species of arsenic and antimony, respectively. At low temperatures, elevated sulfide concentrations, and intermediate pH, arsenic and antimony thiosulfides become dominant. Upon boiling, the precipitation of copper, lead, and silver sulfosalts instead of sulfides is most likely at low temperatures and low pH values. Calculated low-temperature sulfosalt precipitation is consistent with shallow arsenic and antimony mineralization in epithermal systems and also with the commonly observed late precipitation of these metals as temperature decreases with time. Calculated electrum compositions do not exceed 56 mole percent gold. These compositions vary with temperature but depend mainly on the amount of other silver-bearing minerals competing with electrum.Upon boiling, all mercury fractionates into the gas phase from 300 degrees to 101 degrees C. Numerical condensation by cooling the gas phase below 101 degrees C at a constant pressure induces the precipitation of cinnabar between 80 degrees and 100 degrees C, depending on the mercury concentrations (0.8-800 ppb). Arsenic and antimony, however, do not fractionate significantly into the gas phase as long as an aqueous phase is present. Upon 100 percent boiling of the solution, antimony stays in the dry gas phase down to 220 degrees C where stibnite precipitates, and arsenic down to 130 degrees C where realgar precipitates. The transport of base metals in the dry gas phase requires temperatures above 400 degrees C.The acidification of the boiled Broadlands-type water by acid sulfate waters or by H 2 SO 4 produced from magmatic SO 2 leads to the precipitation of gold-rich electrum or gold with copper sulfides (at 200 degrees , 150 degrees , and 101 degrees C), sulfosalts (at 150 degrees and 101 degrees C), and enargite (at 101 degrees C). Acidification in a hot spring environment at 90 degrees C causes orpiment and stibnite to precipitate. Comparative results between H 2 SO 4 and HCl acidification reactions indicate that the replacement of copper, lead, and silver sulfides by sulfosalts is driven by pH decrease and is favored by higher sulfide and sulfate activities. The enargite-covellite-tetrahedrite-chalcopyrite downward zoning of acid sulfate-type epithermal deposits can be explained by acidification at constant sulfide activity. Also, the formation of shallow epithermal deposits rich in gold, relative to silver, can be explained by the reaction at shallow depths between ascending boiling waters and downward percolating acid sulfate waters.
200 citations
TL;DR: In this paper, the most probable stoichiometries of antimony and arsenic sulfide complexes are H2Sb2S4, HSb 2S−4 and Sb 2 S24−, and H3As 3S6, H2As3S6− and HAs 3 S26−.
137 citations
TL;DR: Although Sb 2 O 4, a mixed Sb III Sb V oxide, is well known to posses a two-component Mossbauer Sb spectrum, it is shown to exhibit one-component Sb d-orbital photoemission peaks as discussed by the authors.
78 citations
TL;DR: In this article, a new bidentate ligand, mbit, [mbit=1,1′-methylenebis (3-methyl-2H-imidazole-2-thione)] was synthesized and characterized along with two new pnictogen complexes - SbCl3mbit and BiCl3mit.
57 citations
TL;DR: The 1989 evaluation on mass A=112 has been reviewed, taking into account all data available before December 1995 as mentioned in this paper, and experimental information is presented from the neutron-rich {sup 112}Tc to the neutrally-deficient {sup112}Cs.
48 citations
TL;DR: In this article, the substrate orientation dependence of the surface segregation of antimony and gallium atoms during silicon molecular beam epitaxy (MBE) was studied using the delta doping technique, and it was shown that the incorporation coefficients of both agents have a temperature dependence of thermal activation type.
46 citations
TL;DR: In this article, the mechanism of incorporation of metallic antimony in amorphous films of the Ge 20 Sb x Se 80−x (5⩽ X ⩽25) system is studied by measuring the dc conductivity and optical absorption.
45 citations
43 citations
42 citations
TL;DR: In this paper, a method has been developed for the ultrasensitive determination of arsenic, antimony and selenium by hydride generation with subsequent trapping and atomization in the graphite furnace coated with micrograms of palladium which is used as an adsorber for the hydrides.
42 citations
TL;DR: In this article, the authors presented data for the hydride generation atomic absorption spectrometric determination of arsenic, antimony, bismuth and selenium in stream sediments and a certified reference material.
Abstract: Data are presented for the hydride generation atomic absorption spectrometric determination of arsenic, antimony, bismuth and selenium in stream sediments and a certified reference material (CPB-1 Lead Concentrate) using six different extraction media, viz., hydrochloric acid; nitric acid; 7 M nitric acid; nitric acidsulphuric acid (9 + 1); aqua regia; and reversed aqua regia (HNO3+ HCl, 3 + 1). Extraction with 7 M nitric acid was performed in test-tubes placed in a drilled out heating block (110 °C, 3.5 h). All other extractions were carried out overnight in 50-ml calibrated flasks placed in a water-bath. Bismuth was extracted quantitatively by all the extraction media. Arsenic and selenium were extracted completely by each of the media used, except for hydrochloric acid. Antimony was extracted completely by only two of the media, viz., aqua regia and reversed aqua regia. Selenium is converted to the +4 oxidation state on extraction with aqua regia and reversed aqua regia, i.e., selenium(VI) is reduced to selenium(IV), and the lower oxidation states are oxidised to selenium(IV). Hence the extracts can be analysed for selenium without pre-reduction to selenium(IV), which is necessary for hydride generation atomic absorption spectrometry. The nitric acid-hydrochloric acid mixtures used bring arsenic, antimony, bismuth and selenium quantitatively into solution and are, therefore, suitable for the sequential or simultaneous determination of these elements in a single sample solution. The speciation of selenium in stream sediments and surface waters is discussed.
TL;DR: In this article, a typical catalyst preparation commences with the oxidation and hydration of a lower oxide to Sb 2 O 5 · n H 2 O. During the subsequent stages of drying and calcination, a non-stoichiometric phase is formed, and this in turn yields Sb 6 O 13 and then Sb2 O 4.
TL;DR: In this paper, the ionization potentials of Sb4n clusters are studied as a function of the size and the observed evolution confirms the nonmetallic character of their structure, and the possible metastable character of the Sb 4n structure is discussed and illustrated by experiments performed as the function of inert gas temperature in the clusters source.
Abstract: Antimony clusters are produced by the gas aggregation method. They are found to be built from Sb4 units. The Sb+4n clusters are demonstrated to relax their excess energy by evaporation of a tetramer and the binding energy of Sb4 in the cluster is measured to be about 1.3 eV, well below the binding energy of a Sb atom in the bulk (≊2.75 eV). The ionization potentials of Sb4n clusters are studied as a function of the size and the observed evolution confirms the nonmetallic character of their structure. These results are compared with those obtained for bismuth clusters which exhibit a very different behavior. Finally the possible metastable character of Sb4n structure is discussed and illustrated by experiments performed as a function of inert gas temperature in the clusters source.
Patent•
29 Sep 1989TL;DR: In this paper, organometallic antimony compounds having increased thermal stability that are used in chemical vapor deposition processes are provided which comprise stibines containing sterically-demanding ligands.
Abstract: Organometallic antimony compounds having increased stability that are use in chemical vapor deposition processes are provided which comprise stibines containing sterically-demanding ligands, stibines lacking beta hydrogen atoms, or aromatic stibines. These compounds will generally have the formula: SbR.sub.n X.sub.3-n wherein R is selected from the group consisting of neopentyl, 2-ethylbutyl, 1-ethylpropyl, perhaloalkanes having 3-5 carbon atoms, benzyl, fluoro-substituted phenyl, cyclopentyl, and pentamethylcyclopentadienyl; X is selected from the group consisting of Br, Cl, I and H; and wherein n is an integer from 1 to 3. These compounds exhibit increased thermal stability and are thus advantageously used as substitutes for arsenic or other group V metals in chemical vapor deposition processes. Because of the bulky ligand group bound to the antimony and/or the lack of beta hydrogen atoms in the ligand, theses organometallic stibines are less prone to decompose prematurely and thus exhibit greater thermal stability than previously known alkyl antimony hydride compounds.
CNET1
TL;DR: In this article, spectroscopic ellipsometry is used as a technique for crystal surface analysis, here applied to the study of Sb 4 adsorption on silicon (111), and perfect initial Si(111) surfaces are obtained by removing a 150 A thick oxide at high temperature under a silicon flux.
TL;DR: In this article, the photoproduct [SbCl 6 ] − in CHCl 3 is light-sensitive and shows a phosphorescence (λ max = 520 nm, o = 2.4 X 10 −3, τ ⩽ 50 ns) originating from the lowest sp excited state.
TL;DR: The equilibrium solid solubility of antimony in silicon was determined in the range 850°-1300°C by carrier density measurements on polysilicon films doped by ion implantation as mentioned in this paper.
Abstract: The equilibrium solid solubility of antimony in silicon was determined in the range 850°–1300°C by carrier density measurements on polysilicon films doped by ion implantation. Up to 1150°C this property follows very tightly the exponential dependence with and . The values at higher temperatures show a smaller increase, the figures at 1200°, 1250°, and 1300°C being , respectively. The attainment of the two‐phase equilibrium was confirmed by carrier profile measurements on isothermally annealed single‐crystal specimens doped in a wide range of concentrations, as well as by TEM examinations which detected a high density of particles having the hexagonal structure of antimony. It is shown that the new solubility values, unlike the previous ones, fully comply with the conditions for phase equilibrium. According to this treatment, the values of 0.58 eV and of are deduced for the partial molar enthalpy and, respectively, for the excess partial molar entropy of the dopant in silicon relative to the standard liquid state of antimony.
TL;DR: The structure of Diphenylantimony trichloride and tribromide with acetonitrile is known as MeCN as discussed by the authors, and the structure of MeCN has been shown to have distorted octahedral geometry about antimony, with phenyl groups in trans positions.
TL;DR: In this article, the authors studied the beneficiation properties of other antimony oxides, including pure antimony and jamesite, and showed that the properties of these oxides are similar to those of pyrite and pyrrhotite.
TL;DR: In this paper, substitution reactions of arsenic (III) and antimony(III) acetates with alkylene dithiophosphoric acids in stoichiometric ratios yield mixed complexes, M(OAc)3-x(S2 )x where M = As or Sb, x = 1 or 2 and G = CH2CMe2CH2, CH2CEt2CH 2, CMe2CME2, and CHMeCHMe 2.
Abstract: Replacement reactions of arsenic(III) and antimony(III) acetates with alkylene dithiophosphoric acids in stoichiometric ratios yield mixed complexes, M(OAc)3–x(S2 )x where M = As or Sb, x = 1 or 2 and G = –CH2CMe2CH2–,–CH2CEt2CH2–, –CMe2CMe2–, and –CHMeCHMe–). These derivatives are hydrolizable, yellow/orange powders with varying solubilities in organic solvents. IR and NMR (1H, 13C and 31P) studies indicate bi- arid uni-dentate behaviour of dithiophosphate and acetate moieties, respectively, in these complexes.
TL;DR: In this article, the authors present a review of the state of the art for the extraction of antimony from stibnite ores and summarize the experience from processing plants, focusing on selectivity in the primary Sb flotation.
01 Aug 1989
TL;DR: In this paper, the standard heat of formation and entropy of As/sub 2/O/sub 3/(g) have been evaluated for arsenic and antimony and their sulfide and oxide gases.
Abstract: In this paper thermodynamic data for arsenic and antimony and their sulfide and oxide gases have been critically reviewed and compiled. The entropy values for AsS(g), SbS(g), and BiS(g) have been recalculated based on a statistical thermodynamic method. The standard heat of formation and entropy of As/sub 2/O/sub 3/(g) have been newly assessed. Copper matte converting has been mathematically described using the stepwise equilibrium simulation technique together with quadratic approximations of oxygen and magnetite solubilities in molten mattes. A differential equation for the volatilization of arsenic and antimony has been solved for successive reaction microsteps whereby the volatilization, slagging, and alloying of the minor elements have been examined as functions of reaction time and other process variables. Only the first (slag-making) stage of converting is responsible for the elimination of arsenic and antimony by volatilization. Arsenic volatilizes mainly as AsS(g) and AsO(g), with As/sub 2/(g) also contributing when initial mattes are unusually rich in arsenic (above 0.5 pct arsenic). Antimony volatilizes chiefly as SbS(g), and the contributions of other gases such as SbO(g) and Sb(g) remain negligibly low. The results of the simulation compare favorably with industrial operating data.
TL;DR: In this article, a clean, indium rich surface formed by noble gas ion bombardment and annealing of a bulk sample, displayed a disordered (4 × 2) LEED pattern with sharp features.
TL;DR: Spiral structures are observed on the surface of electrodeposited silver-antimony alloys when plating is carried out under limiting current conditions as discussed by the authors, and the formation of the spiral structures occurs by the simultaneous crystallization of phases with different antimony content.
TL;DR: In this paper, a carbonate coprecipitation technique for preparing Bi1.6Pb0.3Sb 0.1Ca2Sr2Cu3O10 samples is described.
Abstract: We report a carbonate coprecipitation technique for preparing Bi1.6Pb0.3Sb0.1Ca2Sr2Cu3O10 samples. X-rays, microwave absorption and magnetic measurements show that the material is nearly single phase with Tc106 K. The presence of antimony appears to accelerate the formation of -2223 from the -2122.
TL;DR: The energy of the metal-to-ligand charge transfer (MLCT) bands depends on the reducing strength of a metal and the extent of sp mixing of the lone electron pair at the metal.
TL;DR: In this paper, the redistribution reactions with SbCl3 in 2 1 and 1 2 molar ratios were found to give quantitative yields of (C6F5)2SbCl (II) (c6F 5)SbCL2 (III), respectively.