Abstract: A method for decomposing hydrogen peroxide which comprises contacting the hydrogen peroxide with a catalyst having a surface consisting of a mixture of ruthenium with at least one metal of the group consisting of iridium and platinum in which the ruthenium is about 20 to about 70 atom percent of said metals.

Abstract: Methods and reaction systems are disclosed that are adapted for forming crystallites having novel crystal habits and/or morphologies compared to conventional crystallites of the same chemical composition. The methods and reaction systems involve chemical reactions between at least two reactant compounds occurring in a liquid (or gel) that form insoluble crystallite products. At least one of the reactants is rendered soluble in a solvent in which the reactant is not normally soluble by adding an agent that forms soluble molecular complexes of the agent and the reactant. The complexing agent not only facilitates dissolution of the reactant in the solvent but also plays a role in how the faces of crystals comprising the crystallite product are enlarged during formation of the product. Products having such altered crystallite structure have a number of possible uses.

Abstract: A multistage process for the separation and purification of a desired crystalline material by repeated dissolution and recrystallization, wherein crystals and solvent move countercurrent to one another through the stages. A fluid temperature gradient is maintained within each recrystallization unit to make use of convection to facilitate or accelerate concurrent dissolution and recrystallization within a single vessel. Solid recrystallized material is moved from one unit to the next unit. An automated apparatus and a manually operated apparatus for carrying out the process are also described.

Abstract: Silver nitrate crystals comprising a substantially non-platelet crystal morphology are disclosed. The non-platelet silver nitrate crystals have an aspect ratio in the range of from about 1:2:3 to about 1:1:1. FIGS. 4 and 5.

Abstract: This invention relates to a copper etching process which involves contacting the copper with an aqueous etching solution comprising sulfuric acid and a peroxide to which is added less than about 0.2% of an organic additive useful as a crystallization control agent and selected from the group consisting of a low molecular weight glycol and gum arabic. With this compound present, copper sulfate crystals do not adhere to the tank and removal of the crystals from the bath is facilitated.

Abstract: A process is described for recovering tin from oxide or oxide/sulphide low-grade starting materials and concentrates containing little or relatively low concentrations of tin, in which such low-grade starting materials are mixed with KOH and decomposed at high temperatures. The decomposed substance is then leached with water, and metallic tin is separated out electrolytically in one or more stages from the lye. The electrolyte with reduced tin content is concentrated by evaporation, impurities being removed, and dehydrated. The potassium hydroxide solution recovered is re-used for decomposition.

Abstract: A process for the production of aluminum trihydroxide having controlled median diameter of 2 to 100 microns, with a unimodal distribution and minimum deviation, by decomposing a hot supersaturated sodium aluminate solution in the presence of seed aluminum trihydroxide, separating the resultant solid and liquid phases and recovering the solid phase constituted by precipitated aluminum trihydroxide. The process comprises grinding aluminum trihydroxide until the aluminum trihydroxide has a specific BET surface area of at least 1 m.sup.2 /g, introducing the ground aluminum trihydroxide into a hot fraction of the supersaturated sodium aluminate solution to precipitate trihydroxide seed and then decomposing the remaining fraction of the supersaturated sodium alimuniate solution in the presence of the seed. This decomposition leads to the precipitation of aluminum trihydroxide having the required median diameter.

Abstract: A process is disclosed for removing contaminants from impure alkali metal nitrates containing them. The process comprises heating the impure alkali metal nitrates in solution form or molten form at a temperature and for a time sufficient to effect precipitation of solid impurities and separating the solid impurities from the resulting purified alkali metal nitrates. The resulting purified alkali metal nitrates in solution form may be heated to evaporate water therefrom to produce purified molten alkali metal nitrates suitable for use as a heat transfer medium. If desired, the purified molten form may be granulated and cooled to form discrete solid particles of purified alkali metal nitrates.

Abstract: A process is provided wherein metal granules coated with a polymerizable oil are heated, while being mechanically mixed, to a polymerizing temperature to convert the oil coating to a varnish and the varnish coating thereafter heated to a higher temperature to decompose at least partially the varnish to carbon, thereby producing a carbon coating strongly bonded to the metal granules. The temperatures employed are below the melting point of the metal granules. The coating is preferably applied to magnesium, aluminum or alloys thereof for use as addition agents in steel, e.g., desulfurizing or deoxidizing agents, and may contain fine particles of at least one calcium compound.

Abstract: A process for the removal of lead content in anode slime by subjecting the latter to primary and secondary leach in a medium of an ammonium acetate solution at a temperature not exceeding 80.degree. C. Whereby lead dissolution is maximized and other metals are minimized. Separate the leach solution from the undissolved slime residue, crystallize lead from the separated leach solution and recover the crystallized lead acetate.

Abstract: The improved production of sodium sulfate, potassium sulfate and other valuable salts from salt plant bitterns or the like wherein initial reduction in sulfate ion concentration yields salt cake and greatly facilitates the selective recovery of potassium and other valuable by-product salts. The process includes cooling the bitterns while below a certain concentration to produce glauber salt, followed by successive solar evaporation steps to yield harvestable potash salts. The salts are selectively treated and then refined by flotation. The flotation overflow is converted to potassium sulfate product by decomposition and crystallization steps and the underflow provides a recycle salt mixture for converting the glauber salt to salt cake.

Abstract: The specification describes a process for growing selected compound semiconductors of high stoichiometry and purity and includes the steps of providing both a dynamic vacuum and a predetermined temperature profile in a container or tube containing a chosen semiconductor source material. The dynamic vacuum is used to create a predetermined minimum overpressure. P.sub.min, in this container with respect to the vapor pressure of the source material, while simultaneously removing impurities through in opening in the container during the crystal growth process. This process involves the vapor transport of elements of the selected compound semiconductor from the source material to a suitable support member, such as a graphite crucible which is maintained at a predetermined uniform controlled temperature.

Abstract: A method of crystallizing zirconium or hafnium oxychloride to remove metallic impurities and phosphorus by maintaining the normality of the mother liquor in which the zirconium or hafnium tetrachloride is dissolved.

Abstract: In a dual temperature isotope exchange system--exemplified by exchange of deuterium and protium between water and hydrogen sulfide gas in hot and cold towers, in which the feed stream (water) containing the desired isotope is passed through a pair of towers maintained at different temperatures wherein it effects isotope exchange with countercurrently circulated auxiliary fluid (H.sub.2 S) and is impoverished in said isotope and then disposed of, e. g. discharged to waste,--the flow of isotope enriched auxiliary fluid between said towers (hot H.sub.

Abstract: Clusters or galaxies of noble metal silver-precipitating nuclei for use in silver diffusion transfer processes are formed by reducing a noble metal salt or complex to form a colloid of noble metal nuclei and inducing instability to said colloid, whereby said galaxies are formed.

Abstract: Crystals are grown from solution by the introduction of a first fluid into a second fluid by permeation through a porous partition. Introduction of the first fluid produces supersaturation of the desired material in the combined fluid in the vicinity of the partition. Supersaturation results in the production of crystals. The crystals grow from the partition into the solution. The supersaturation is produced by one of several mechanisms including: chemical reaction producing a less soluble element or compound; decomplexation produced by dilution or pH change; and introduction of solution into a solvent in which the material is less soluble.

Abstract: A tetrafluoromethane (CF.sub.4) generator and process is disclosed that facilitates the relatively low temperature production of CF.sub.4 gas via controlled decomposition of polytetrafluoroethylene (Teflon) and tetrafluoroethylene (C.sub.2 F.sub.4). CF.sub.4 produced via this process proves to be an excellent OH.sup.- scavenger in the processing and growth of metal fluoride single crystals.

Abstract: A method and horizontal furnace for vapor phase growth of HgI.sub.2 crystals which utilizes controlled axial and radial airflow to maintain the desired temperature gradients. The ampoule containing the source material is rotated while axial and radial air tubes are moved in opposite directions during crystal growth to maintain a desired distance and associated temperature gradient with respect to the growing crystal, whereby the crystal interface can advance in all directions, i.e., radial and axial according to the crystallographic structure of the crystal. Crystals grown by this method are particularly applicable for use as room-temperature nuclear radiation detectors.

Abstract: In a hydrothermal process for manufacturing crystals of metal carbonates, including single crystals of lead carbonate of the cerussite crystalline form, the nutrient material consists of a carbonate or basic carbonate of the said metal, the solvent medium consists of a 0.5 to 5.0 molar aqueous solution of an alkali metal bicarbonate, and the heating is carried out in an autoclave under controlled temperature conditions such that the exterior of the autoclave wall adjacent to the nutrient and the solvent medium in the vicinity thereof is maintained at 200.degree. C to 400.degree. C, and that the exterior of the autoclave wall adjacent to the region of the solvent medium remote from the nutrient is maintained at 170.degree. C to 315.degree. C and at a temperature from 5.degree. C to 150.degree.

Abstract: In a process of preparing single crystals of strontium barium niobate of the type wherein melt of a mixture of strontium oxide, barium oxide and niobium pentoxide is prepared and a single crystal of strontium barium niobate is grown from the melt by using a seed crystal, the compositions included in region A or B shown in FIGS. 2 and 3 are used as the ternary compositions of strontium oxide, barium oxide and niobium pentoxide in the melt.

Abstract: A composition of matter transparent to infrared rays and shock resistant which is a directionally grown, polycrystalline solidified melt of a eutectic composition comprising at least two components wherein the ratio of the index of refraction of one to the other is within the range of 1.2 to 1.0, the directionally oriented, polycrystalline mass is grown in a controlled manner by adding heat to the melt and removing the same from the solids during the solidification step, the amount of heat being added to the melt and conducted through the solidified melt being 10.sup.3 to 10.sup.5 times the latent heat of fusion of the eutectic mixture.

Abstract: The present invention relates to a method and apparatus for purifying selenium or its alloys by precipitation. The method is characterized in that a smaller portion of a larger amount selenium or selenium alloy is kept at the respective transition temperature between solid and liquid phases while the remaining portion is maintained at a higher temperature for a time sufficiently long to allow a substantial concentration of foreign elements in the smaller portion.The apparatus is characterized in that it consists of a glass vessel having a height approximately 10 times its diameter, provided with temperature indicators governing devices controlling the heat supplied to electrical elements arranged around the vessel, it also being provided with a tightly-fitting hood and a gas evacuation device.

Abstract: A process is disclosed for separating cuprous chloride from a solution comprising cuprous chloride and at least one metal chloride compatible with the solubility of cuprous chloride, the process comprising crystallizing the cuprous chloride from the solution in the presence of cupric chloride in an amount such that the cupric chloride to compatible metal chloride mole ratio is at least about 0.1.

Abstract: A method and a device for vapor growing crystals. The crystals are grown in an evacuated ampoule from a liquified sample source material, such that the source material is separated from the growing crystal by one or more capillaries or the like which provide the only pathway between the sample source and the growing crystal. There is a temperature gradient between the sample source and the growing crystal such that the growing crystal is at a lower temperature than the sample source.

Abstract: Dimethylsulfoxide is used as a solvent for the growth of red mercuric iodide (HgI.sub.2) crystals for use in radiation detectors. The hygroscopic property of the solvent allows controlled amounts of water to enter into the solvent phase and diminish the large solubility of HgI.sub.2 so that the precipitating solid collects as well-defined euhedral crystals which grow into a volume of several cc.

Abstract: Method of growing single crystal of Bi.sub.4 Ti.sub.3 O.sub.12 by a top-seeded growth technique. A solution of TiO.sub.2 is a solvent consisting of Bi.sub.2 O.sub.3 with/without B.sub.2 O.sub.3 is prepared. The temperature of the solution is adjusted to a value which is not more than 5.degree.C above the saturation temperature of the solution, and is maintained at this value while the degree of saturation of the solution is increased by dissolving TiO.sub.2. A Bi.sub.4 Ti.sub.3 O.sub.12 seed crystal is then lowered into the solution which is gradually cooled so as to grow a single crystal. The transparency of crystals grown from a solution containing B.sub.2 O.sub.3 in addition to Bi.sub.2 O.sub.3 is better than that of crystals grown from solutions in which the solvent consists solely of Bi.sub.2 O.sub.3.

Abstract: Single crystals of Hg.sub.3 TeO.sub.6, which are useful in, for example, acousto-optic applications, are grown on rotating seed crystals in aqueous solution at an elevated temperature. A two-step process is employed in which supersaturation is achieved by a substantially homogeneous increase in pH throughout the solution under substantially isothermal conditions, followed by a decrease in temperature at substantially constant pH. The homogeneous increase in pH is attained by adding a compound such as urea whose rate of hydrolysis may be controlled by solution pH and temperature. The use of such a compound ensures thorough mixing of the compound in the solution before the compound hydrolyzes to produce a pH-altering substance.

Abstract: Processes for preparing vanadium- and chlorine-free sodium bichromate which comprises concentration of a sodium chromate liquor so as to cause formation of crystals of neutral sodium chromate tetrahydrate, separation of these crystals from their mother liquor, treatment thereof with sulfuric acid, concentration of the acid solution obtained, and after separation of insoluble sodium sulfate so formed, crystallization of sodium bichromate.