Abstract: After a chalcogen film 3 is applied to an acute tip 2 of a glass fiber 1, the acute tip 2 is held in physical contact with a metal layer 5 so as to induce diffusional reaction for generation of a metal chalcogenide nano-particle or nano-particles 6 at the acute tip 2. In the case where the chalcogen film 3 is directly applied to the acute tip 2, the generated nano-particle or nano-particles 6 are transferred from the acute tip 2 to a corresponding part of the metal layer 5. When a silane-adsorbed film 4 is pre-formed on the acute tip 2 before application of the chalcogen film 3, the generated nano-particle or nano-particles 6 are fixed to the acute tip 2. The nano-particles 6 are several to tens in number with very narrow distribution of particle size. Since particle size and fixed position of the nano-particle or nano-particles 6 can be controlled with high freedom, the nano-particle or nano-particles 6 are useful as a light-emitting or photo-detecting element.

Abstract: A process for preparing a nanocrystalline material comprising at least a first ion and at least a second ion different from the first ion, and wherein at least the first ion is a metal ion, is described. The process comprises contacting a metal complex comprising the first ion and the second ion with a dispersing medium suitable to form the nanocrystalline material and wherein the dispersing medium is at a temperature to allow formation by pyrolysis of the nanocrystalline material when contacted with the metal complex.

Abstract: Sulphides and selenides are prepared by dissolving sulphur or selenium in an aqueous or non-aqueous solution of hydrazine hydrate. The solution is combined with a solution of an appropriate cation to precipitate the corresponding sulphide or selenide. Solutions of two or more cations may be used to produce ternary compounds of sulphur and selenium, for example thio-gallates. Likewise both sulphur and selenium can be used together to produce sulpho-selenides. The method is particularly applicable to the production of doped phosphors by the inclusion of solutions containing the appropriate dopant.

Abstract: A process for preparing a nanocrystalline material comprising at least a first ion and at least a second ion different from the first ion, and wherein at least the first ion is a metal ion, is described. The process comprises contacting a metal complex comprising the first ion and the second ion with a dispersing medium suitable to form the nanocrystalline material and wherein the dispersing medium is at a temperature to allow formation by pyrolysis of the nanocrystalline material when contacted with the metal complex.

Abstract: The present invention is directed to a method for removing selenium from a waste stream. The process is a multi-step process that removes selenium from a waste stream in the form of barium selenate and/or barium selenite. In a further step, the barium selenate and/or barium selenite forms a complex precipitate with barium sulfate, which encapsulates the barium selenate and/or barium selenite. The complex precipitate is subsequently removed from the waste stream.

Abstract: The present invention relates to an apparatus for removing volatile impurities such as mercury and selenium from a weak acid solution resulting from scrubbing gases created in the production of sulfuric acid by roasting of sulfide concentrates. The apparatus comprises a calcine filtering unit for removing calcine from the weak acid solution, a sodium sulfide mixing unit for precipitating mercury from the weak acid solution, a sodium dithionite mixing unit for precipitating selenium from the weak acid solution, and a mercury-selenium filtering unit for filtering the precipitated mercury and selenium from the weak acid solution. The present invention further relates to a treatment plant utilizing such an apparatus, a process for removing volatile impurities from a weak acid solution, and a selenium cake obtained by utilizing the resent invention.

Abstract: A new method for improving the mechanical properties and nonlinear optical performance characteristics of gallium selenide crystals (GaSe) is disclosed. A charge of GaSe crystals was doped with indium before being made into a crystal. The indium-doped GaSe crystals have improved physical properties in that they can be cut along the cleave planes and the cleaved surfaces polished without the usual delaminations typically observed in prior art pure GaSe crystals. The indium-doped crystals were tested in a second harmonic generation (SHG) system and found to have nearly twice the SHG efficiency as pure, or undoped, GaSe crystals.

Abstract: The present invention is concerned with a method for the substantially selective extraction of tellurium from copper electrorefining slimes. The method comprises maintaining a molar ratio Ag/Se, Ag/S or Ag/Se+S at a value of about 2 or less in the slimes during leaching thereof in an autoclave. The excess of selenium and/or sulphur allows the formation of Ag.sub.2 Se or Ag.sub.2 S, which remains insoluble during autoclave leaching.

Abstract: An aqueous system for the production of metal chalcogenide nanocrystalline salts such as zinc selenide, from a hydrolyzable chalcogen carbonyl compound, such as selenourea, by simple hydrolysis thereof under alkaline conditions in the presence of water soluble metal hydroxide, such as zinc hydroxide in the form of the zincate ion, i.e., Zn(OH).sub.4.sup.-2. Selenourea contains selenium in the correct oxidation state, is inexpensive, commercially-available and readily hydrolyzable under aqueous basic conditions in the presence of the zincate ion to form zinc selenide. The zinc selenide is insoluble in the alkaline aqueous vehicle and precipitates over time in the form of nanocrystallites or quantum dots of the zinc selenide.

Abstract: A selenium-containing aqueous stream may be used as a quenching water stream and optionally a cutting water stream in a delayed coking process to effectuate the removal of selenium from the selenium-containing aqueous stream resulting in the formation of a selenium-coke product. In addition, selenium may be concentrated in selenium-containing stripped sour water streams by recycling the stream in one or more hydroprocessing units and one or more sour water stripper units and subsequently removed by using a portion of the selenium-containing stripped sour water stream as a quenching water stream and optionally a cutting water stream in a delayed coking process.

Abstract: Hydrogen and/or carbon impurities are removed from chalcogenide or chalcoide glasses by the addition of a halide, such as TeCl.sub.4, to the batch composition. During melting of the batch composition, the metal halide reacts with the hydrogen and/or carbon impurities to form a hydrogen halide and/or carbon tetrahalide gas and a metal which becomes incorporated into the chalcogen-based glass. Useful halides include halides of sulfur, selenium, tellurium, polonium, or halides of a metal (such as aluminum, magnesium, zirconium, or a mixture thereof) that forms a stable oxide. Mixed metal halides may also be used. The glass melt is then distilled, outgassed, homogenized, fined, and annealed. An apparatus specially designed for making a fiber preform by the above process is also described. An annealed preform made by this method may be drawn into a low-loss fiber in the 2 .mu.m to 12 .mu.m range.

Abstract: A process for chemical bath deposition of selenide and sulfide salts as films and powders employable as precursors for the fabrication of solar cell devices. The films and powders include (1) Cu.sub.x Se.sub.n, wherein x=1-2 and n=1-3; (2) Cu.sub.x Ga.sub.y Se.sub.n, wherein x=1-2, y=0-1 and n=1-3; (3) Cu.sub.x In.sub.y Se.sub.n, wherein x=1-2.27, y=0.72-2 and n=1-3; (4) Cu.sub.x (InGa).sub.y Se.sub.n, wherein x=1-2.17, y=0.96-2 and n=1-3; (5) In.sub.y Se.sub.n, wherein y=1-2.3 and n=1-3; (6) Cu.sub.x S.sub.n, wherein x=1-2 and n=1-3; and (7) Cu.sub.x (InGa).sub.y (SeS).sub.n, wherein x=1-2, y=0.07-2 and n=0.663-3.

Abstract: A method for dealing with mercury-containing waste including button-type batteries, wherein the waste is heated in a furnace while being agitated and in the presence of elementary selenium vapour in an amount sufficient to form mercury-selenide from essentially all the mercury contained by the waste. The waste is heated to a temperature at which mercury and selenium will be present in a gaseous state and at which solid mercury-selenide will not form, and a partial pressure of oxygen is maintained at a sufficiently low level to avoid oxidation of the selenium. The thus treated mercury-freed waste is extracted from the resultant process gas and from any other solid material that may be present and is either dumped or worked-up metallurgically.

Abstract: Small diameter fibers formed from the use of laser energy and gaseous reactants and are disclosed. Also disclosed is an apparatus and method for the formation of continuous, substrate free, crystalline or amorphous fibers. Materials which can be formed into small diameter fibers include boron, silicon, germanium, zinc, tungsten, cadium, gallium, thenium, and compounds and mixtures thereof. The fibers have a diameter of about 10 micrometers to about 170 micrometers. The apparatus for producing the fibers includes a laser, a reaction chamber, and gas supply means. The laser beam has a focal point adjusted to coincide with the tip of the growing fiber, the focal point of the laser creating a region of elevated temperature at the fiber tip.

Abstract: A process for producing bismuth telluride including dissolving tellurium to form a first solution; heating the first solution to approximately 70.degree. C.; stirring the first solution; slowly and quantatively adding an amount of bismuth trioxide (Bi.sub.2 O.sub.3) to produce a Bi/Te second solution wherein the ratio of Bi: Te=2:3; cooling the second solution to approximately 25.degree. C.; preparing a solution of concentrated aqueous ammonia and distilled water; adding the solution of aqueous ammonia and distilled water dropwise to the second solution at approximately 25.degree. C. to form a third solution; rapidly stirring the third solution to produce a precipitate therefrom; separating the precipitate from the third solution by centrifugation; washing the separated precipitate in distilled water; drying the washed precipitate in air to produce a Bi.sub.2 Te.sub.3 O.sub.9.xH.sub.2 O, where x=1, precursor powder; heating predetermined quantities of the dried precursor powder to 250.degree. C.-275.degree.

Abstract: A method for manufacturing an ultrafine gold and/or silver chalcogenide being used for the sensitivity speck seeding sensitization method is disclosed. The gold and/or silver compound, and a water-soluble chalcogenide are mixed into a protective colloid solution under prescribed condition. The light-sensitive photographic material obtained by this method has a high sensitivity and low fog property.

Abstract: A method of increasing the extraction of tellurium from copper electrorefining slime comprises leaching the slime with dilute sulphuric acid in a reactor under a partial oxygen pressure of up to 150 psi and at an elevated temperature between about 100.degree. and 200.degree. C. until copper, nickel and substantially all of the tellurium is dissolved, thereby forming a leach slurry, and contacting the slurry with an appropriate reducing agent immediately after the leaching operation has been halted and the leaching reactor brough back to atmospheric pressure to reprecipitate any excessive quantities of silver and selenium solubilized during the leaching operation.

Abstract: The method involves producing a multi-component glass doped with CdS.sub.x Se.sub.y Te.sub.z microparticles. The process has solved the conventional problems that the chalcogen element(s) to constitute the microparticles is (are) vaporized at the step for obtaining a glass melt, by specifying (a) the material to become a glass matrix and (b) the atmosphere used for obtaining a glass melt. The method involves using a mixture of elemental Cd and at least one of the elements S, Se and Te.

Abstract: A system for generating a gaseous polyhydridic Group IV-VI compound, comprising a vessel containing a solid precursor metal compound for the polyhydridic Group IV-VI compound, and a source of a fluid-phase protonic activator compound reactive with the precursor compound to yield as reaction product (a) the polyhydridic compound and (b) a solid reaction product compound containing the metal moiety, e.g., a non-volatile metal salt, together with means for flowing the activator compound from the source thereof to the vessel containing the solid precursor compound. The precursor compound may suitably comprise a metal moiety such as lithium, sodium, magnesium, zinc, potassium, aluminum, and intermetallic complexes and alloys thereof. In a preferred aspect, wherein arsine is generated, the precursor compound may suitably comprise a metal arsenide, and the protonic activator compound is water or an acid such as hydrogen chloride.

Abstract: A multi-component glass doped with microparticles of CdS.sub.x Se.sub.y Te.sub.z, which can be used as a material for sharp cut filter, a material for infrared-transmitting filter or a nonlinear optical material. This glass has solved the problems of conventional glasses doped with microparticles, of (a) being low in microparticles concentration and accordingly having a low spectral characteristic when made into a thin filter and (b) being low in microparticles concentration and accordingly having low third-order nonlinearity, by containing microparticles at a high concentration, i.e. 5-50% by weight. The present invention relates to a process for producing the above multi-component glass doped with CdS.sub.x Se.sub.y Te.sub.z microparticles.

Abstract: The new compound diallyl telluride and other diorgano telluride compounds are prepared from alkali metal tellurides obtained by an efficient reaction between an alkali metal and tellurium in a naphthalene/tetrahydrofuran solution. The alkali metal telluride then reacts with an organo halide to form the final product which is easily isolated by filtration followed by vacuum distillation.

Abstract: A process for the preparation of a chalcogenide alloy which comprises the evaporation of a mixture of a chalcogenide alloy and a metal oxide. Also, there is disclosed a process for controlling the fractionation of chalcogenide alloys which comprises providing a mixture of chalcogenide alloy, and a metal oxide; and subsequently subjecting the resulting mixture to evaporation; and a process for controlling the fractionation of selenium alloys which comprises providing a selenium alloy; admixing therewith a metal oxide; and subsequently subjecting the resulting mixture to evaporation.

Abstract: A method for purifying a gaseous hydride, which comprises bringing a crude gaseous hydride into contact with at least one material from nickel arsenides, nickel phosphides, nickel silicides, nickel selenides, or nickel borides to remove oxygen contained in the crude gaseous hydride.

Abstract: The disclosure relates to a method of purifying cadmium and tellurium and forming pure, stoichiometric cadmium telluride therefrom as well as the apparatus for making such cadmium telluride. The cadmium and tellurium are purified by heating each separately to volatilization and passing water in a reducing gas through the volatilized cadmium and tellurium to react with impurities and form gases or precipitates. The cadmium and tellurium are volatilized at different predetermined temperatures such that the amount of each volatilized will be the same so that reaction later takes place with stoichiometric amounts of the elements to form the cadmium telluride. The cadmium telluride is then condensed at low enough temperature so that the remaining gases pass out of the system.

Abstract: A process of making a lithium cell with a positive electrode that comprises a niobium chalcogenide (e.g., NbSe.sub.3) active material. The process comprises forming the active material by a procedure that comprises forming a layer of Nb powder on an inert substrate (e.g., an alumina plate), and reacting the powder with selenium or sulfur vapor such that the desired (fibrous) chalcogenide is formed. The powder layer typically is formed by depositing (e.g., by spraying) a layer of slurry on the substrate, with the slurry comprising a liquid such as propylene glycol and Nb powder, and removing the liquid from the deposited slurry. The resulting layer of Nb powder can be of uniform thickness, advantageously is less than 0.1 mm thick, and adheres relatively well to the substrate. In preferred embodiments reacting the Nb powder with Se vapor comprises a two-stage heat treatment, the first stage comprising maintaining the powder in contact with Se vapor for at least four hours at a temperature in the range 520.

Abstract: This invention relates to a crystalline composition having a three-dimensional microporous structure of MA.sub.2 units where A is sulfur or selenium and having the empirical formula expressed in molar ratios: xR:MA.sub.2.+-.0.2 :zH.sub.2 O where R represents at least one organic templating agent present in the intracrystalline pore system, x is the moles of R, z is the moles of water and M is germanium or tin. This invention also relates to a composition having the empirical formula expressed in molar ratios: xR:M.sub.1-y M'.sub.y A.sub.2.+-.0.2 :zH.sub.2 O, where M' is a metal such as cobalt, zinc, manganese, iron, nickel, copper, cadmium and gallium. This invention further relates to a method of preparing the crystalline composition.

Abstract: A method for preparing compounds of sulfur, selenium, and tellurium includes the formation of the compound from the elements in a closed environment which excludes oxygen, and then the purification of the compound by contacting it with carbon or carbon monoxide. Oxygen, the principal contaminant in conventionally prepared compounds of this group, is excluded from the formation of the compound in the formation step by using a closed reactor, preferably made of vitreous silica. Oxygen in the initial elemental reactants remains in the compound made in this way, and the purification step eliminates the oxygen originally present in the elemental reactants from the compound. Arsenic triselenide made by this approach, glassy and of high purity, is suitable for use in applications requiring infrared transparency.

Abstract: A scavenger, having utility for purifying a mixture comprising:(i) a primary component selected from one or more members of the group consisting of hydrogen selenide and hydrogen telluride, and(ii) impurities selected from one or more members of the group consisting of moisture and oxidants, comprising:(a) a support; and(b) associated with said support, one or more members of the group consisting of:(I) precusor compounds of the formula R.sub.3-x AlH.sub.x, wherein x is 0 or 1, and R is a hydrocarbon radical containing from 1 to 12 carbon atoms; and(II) aluminum chalconides of the formula Al.sub.2 M.sub.3, wherein M is selenium or tellurium.Illustrative supports useful in such scavenger include aluminosilicates, alumina, silica, carbon, and macroreticulate polymers. A process and apparatus are disclosed for purifying hyhrogen selenide and/or hydrogen telluride, to remove moisture and/or oxidant impurities therefrom, in which a bed of the scavenger is employed.

Abstract: A method for preparing single-crystal ZnSe comprising the steps of:working polycrystalline ZnSe into a rod-shaped starting material;placing the starting material in a reaction vessel;filling the atmosphere of the reaction vessel with an inert gas, nitrogen, H.sub.2 Se gas, or a mixture thereof at from about 0.1 to about 100 Torr; andconverting the polycrystalline ZnSe starting material to single-crystal ZnSe, while maintaining a solid phase, by moving the reaction vessel at a rate of from about 0.05 to about 5 mm/day through a temperature profile consisting of a cool zone AB having a temperature T.sub.1 in the range of from about room temperature to about 100.degree. C., a temperature increasing zone BC having a temperature gradient of from about 50.degree. to about 200.degree. C./cm, a hot zone CD having a temperature T.sub.2 in the range of from about 700.degree. to about 900.degree. C., a temperature decreasing zone DE having a temperature gradient of from about -200.degree. to about -50.degree. C.

Abstract: The present invention provides a process for producing carbon dichalcogen polymers having a conductivity of about 10.sup.-8 S/cm without doping treatment which is increased to 10.sup.-4 to 10.sup.-2 S/cm by doping, by polymerizing carbon dichalcogenide monomers (carbon disulfide, carbon diselenide, etc.) in the form of a solution thereof under a low pressure in the presence of an anionic catalyst.

Abstract: A process for the direct synthesis of high surface area amorphous chalcogenides of transition metals of Group IV, V, VI and VII elements, comprising the steps of:(1) forming a mixture of:(a) a halide of a said transition metal having the formula MY.sub.n where Y is chlorine, bromine, flurorine, or iodine, and n is 3, 4, 5 or 6, and(b) a source of chalcogen selected from compounds having the formula (R).sub.3 Si--X--Si(R).sub.3 wherein R is alkyl having from 1-4 carbon atoms and X is sulfur, selenium or tellurium,(2) reacting said mixture at a temperature of -77.degree. C. to +160.degree. C.;(3) separating the transition metal chalcogenide from the reaction mixture; and(4) washing said chalcogenide with an inert solvent to remove unreacted materials and the byproducts of the reaction.The high surface area amorphous chalcogenides prepared according to the covalent exchange process of the invention are advantageously used in primary or secondary batteries, particularly lithium cells.

Abstract: A hydrometallurgical process for enrichment of gold, platinum and palladium from copper electrolysis anode sludge, and simultaneously recovery of selenium, in which the sludge is treated with Cl.sub.2 /HCl to transform the selenium of a hexavelent state and precipitate out silver chloride. The filtrate is then subjected to selective reduction of precipitate the noble metals and the resulting filtrate is chlorinated and a further reduction is effected to precipitate the metallic selenium.

Abstract: A method for treating a heavy metal-containing liquid, such as a wastewater stream, oil for recycling, or other metal-bearing liquid, with a trithiocarbonate, particularly an alkali metal trithiocarbonate, such as sodium trithiocarbonate, to precipitate the metals as insoluble sulfides. The precipitated metal sulfides are recovered as a low volume sludge, which can be processed through standard metallurgical techniques to yield the metals in economically useful forms. Among the most unexpected results produced by this method is the lowering of the selenium content in a naturally occurring body of water from 1.0 ppm to 0.0015 ppm.

Abstract: A method for forming metal chalcogenides is disclosed. An atmosphere of an elemental middle chalcogen is formed and a metal is reacted with the chalcogen in the vapor phase to form a metal chalcogenide powder.

Abstract: Whiskers comprising needle- or rod-shaped single crystals of tellurium oxide. They are produced by firing metallic tellurium at a temperature of at least 400.degree. C. in an atmosphere containing oxygen.

Abstract: A hydrometallurgical process is provided for separating heavy metal nuisance elements such as As, Sb, Bi, Sn and Pb from precious metals and/or selenium. The process can be used as a step in an overall hydrometallurgical process for treating refinery residues such as anode slimes for the separation and recovery of valuable metal values.

Abstract: This invention constitutes a method of preparing molecular and supramolecular aromatic organic telluride, ditelluride, diselenide and selenide compounds from aromatic halogen compounds which are unactivated toward nucleophilic substitution. The method involves the reaction of an aromatic halide with an alkali metal telluride, ditelluride, selenide or diselenide reagent formed from chalcogen and alkali metal trialkylborohydride to yield the corresponding molecular or polymeric aromatic telluride, ditelluride, selenide or diselenide. Further, the alkali metal chalcogenide reagent prepared from alkali metal trialkylborohydrides may also be used to synthesize molecular and polymeric olefinic tellurides and selenides from olefinic halides unactivated toward nucleophilic substitution.

Abstract: A process for the pressure oxidation leaching of non-ferrous metal sulphidic material which comprises providing an autoclave assembly which has a series of successive compartments, the first compartment of which being substantially larger in size than each of the remaining compartments. An oxygen partial pressure is provided in the autoclave assembly in the range of from about 50 to about 2000 kPa. An aqueous slurry of the material is fed into the relatively large first compartment with resultant flow of the material through the successive smaller compartments causing the temperature in the first and successive compartments to be sufficient to produce autogeneous oxidation of the sulphidic material. The oxidized slurry from the last compartment of the series is discharged.

Abstract: This invention constitutes a method for preparing molecular and polymeric aromatic selenide compounds such as bis-phenyl selenide and poly(p-phenylene selenide). The method comprises reacting an aryl halide with an alkali metal selenide reagent formed in an aprotic solvent.

Abstract: A process for preparing a large ZnSe single crystal, comprising vacuum sealing polycrystalline ZnSe prepared by a chemical vapor deposition in a capable and hot isostatically pressing polycrystalline ZnSe in the capsule, by which the ZnSe single crystal having such high qualities as to be used as a substrate on which an epitaxial layer of ZnSe can be grown.

Abstract: Disclosed is a process for the preparation of high purity chalcogenide alloys which comprises providing an acid mixture of the chalcogens; forming a solution thereof; and thereafter reacting the solution with a reducing agent.

Abstract: A process for separately recovering platinum group metal values, nickel values and copper from nickel-copper-iron sulphidic matte containing platinum group metals includes leaching ground matte at atmospheric pressure in acidic nickel-copper sulphate solution at a temperature in the range of from about 75.degree. to about 105.degree. C. and at a pH below about 4 initially under oxidizing conditions and subsequently under neutral or non-oxidizing conditions to cause dissolution of nickel and iron, precipitation of copper as a copper sulphide and precipitation of dissolved platinum group metals. The copper, nickel and platinum group metal containing solids are separated from the nickel and iron containing sulphate solution and are leached in acidic nickel-copper sulphate solution under pressurized oxidizing conditions at a temperature of from about 120.degree. to about 180.degree. C. to cause dissolution of nickel and copper with minor dissolution of platinum group metals.

Abstract: In order to obtain substances that are optically transparent in the infrared range, usable in the manufacture of optical fibers or radiation emitters, a metal or metalloid chalcogenide other than an oxide is produced by a double-substitution reaction between a starting chalcogen compound--particularly a hydride such as H.sub.2 S, H.sub.2 Se or H.sub.2 Te--and a salt of the desired metal or metalloid, e.g. a chloride. The starting compound and the reactant salt preferably are vaporized at a temperature below the melting point of the resulting metal chalcogenide which thereupon precipitates in the reaction chamber.

Abstract: Intercalatable layered or lamellar stable transition metal chalcogenides, such as CrS.sub.2, usable as cathode active materials and intercalatable layered or lamellar stable alkali metal-transition metal chalcogenides, such as LiCrS.sub.2, usable as cathode active materials as well as anode active materials are synthesized by ion implantation and annealing techniques.

Abstract: A method for producing crystals of materials is described. The method comprises providing a pressure-resistant body having a nucleus of a starting material being crystallized in the inside thereof. The nucleus is applied with an energy which is capable of passing through the pressure-resistant body and being absorbed by the starting material, by which the nucleus is heated and melts. The melt is then gradually cooled under pressure to form crystals of the material. A laser beam or high frequency induction heating technique is used for heating the nucleus.

Abstract: Disclosed is a process for the preparation of chalcogenide alloys in high purity which comprises providing a solution mixture of oxides of the desired chalcogens, and subsequently subjecting this mixture to a simultaneous coreduction reaction.

Abstract: A large polycrystalline body of a 2,6 or 3,5 volatile compound is produced in a graphite crucible under low external pressure by passing a narrow molten zone through a charge of the compound contained in the graphite crucible the interior of which is coated with pyrolytic graphite. By a similar technique, but by use of a hot zone cooler then the molten zone, the polycrystalline body is converted to a monocrystalline body.

Abstract: A process for growing crystals of an inorganic material by forming a solution of the material in a solvent for the compound, forming a film of the solution and etching the solvent from the film with an etching gas until crystals of the material form. The solution has a solidification temperature lower than the melting or sublimation temperature of the material and higher than the condensation temperatures of the etching gas and of reaction products formed by the etching. The etching temperature is between the solidification temperature of the solution and the melting or sublimation temperature of the material and is lower than the vaporization temperature of the solvent and solution and higher than the condensation temperatures of the etching gas and reaction products.

Abstract: A process for reducing the concentration of selenium ions in the Se(VI) oxidation state in an aqueous solution. The aqueous solution is admixed with a quantity of metallic iron. The iron reduces the selenium ions from the Se(VI) oxidation state to a lower oxidation state and then dissolves in the aqueous solution. If the pH level of the aqueous solution is above about 2.3, the selenium ions are reduced to at least the Se(IV) oxidation state and the dissolved metallic iron hydrolyses to form an iron hydroxide that precipitates. The precipitated material is separated from the aqueous solution to provide a solution having a lower concentration of selenium ions. If the pH level of the aqueous solution is below about 2.3, no iron hydrolysis is observed to occur. At least a portion of the selenium in the Se(VI) oxidation state is believed to be reduced to the elemental state. The elemental selenium then is separated from the aqueous solution to provide a solution having a lower concentration of selenium ions.

Abstract: A method is described for the preparation of chalcogenides of ruthenium, rhodium, osmium and iridium transition metals of the Periodic Table of the Elements which comprises mixing in the absence of an aqueous solvent a Group VIII transition metal salt with a source of chalcognide, said chalcogenide being selected from the group consisting of sulfur, selenium, tellurium and mixtures thereof, yielding a precipitate of the formula MX.sub.y wherein M is selected from the group consisting of ruthenium, rhodium, and osmium and iridium, X is sulfur, selenium, tellurium and mixtures thereof and y is a number ranging from about 0.1 to about 3, preferably 0.1 to about 2.5. By the practice of the nonaqueous synthesis technique, Group VIII chalcogenides are prepared which are finely divided, have a high surface area, small particle size and small crystallite size which are also free of excess sulfur, water and/or hydrolysis products. Layered stoichiometric osmium disulfide is prepared by this technique.