Abstract: Method of growing single crystal of bismuth silicon oxide from a melt of Bi.sub.x Si O.sub.1.5x+2, in an oxygen containing atmosphere. At the start of crystallization, x has a value of 11.55 to 11.82 or 12.35 to 14.00. The value of x does not have a spread of more than 0.025 throughout the crystal.

Abstract: Methods of growing crystals by the Czochralski method in which a member having a central vertical passageway extending through it is floated on the melt, and the crystallization is caused to take place within this passageway. The passageway may be parallel sided or tapering from top to bottom and is such that the melt does not wet the walls of the passageway. Excellent diameter control of the grown crystal is obtainable, and since the member floats on the melt during crystallisation, its position follows changes in the level of the melt as the material is pulled from the melt. In one embodiment, the member is porous and fluid is forced through the porous wall of the passageway from a cavity within the member to form a barrier to keep the melt out of contact with the wall of the passageway. In another embodiment, a liquid encapsulant is used, which forms a coating over the whole surface of the floating member including the wall of the passageway.

Abstract: Method of manufacturing gallium nitride crystals by reaction of galium halide and ammonia in which free hydrogen chloride is introduced into the reaction and deposition zones.

Abstract: An apparatus for precipitating and separating a material in a solid form from a gaseous mixture. The substance which is settling in solid form can be very simply prevented from accumulating near the inlet by providing at least one channel with at least one controllable bypass.

Abstract: A process for recovering ammonium sulphate from an aqueous ammonium sulphate solution containing organic contaminants is disclosed. The aqueous solution is contacted with an organic substance which is water soluble and which is capable, in combination with a saturated ammonium sulphate solution, of forming a two-layer system. The organic substance is selected from the group consisting of lactames of 4 to 20 carbon atoms, and mixtures thereof. The resultant two layers may be separated into an aqueous phase containing the ammonium sulphate, and an organic phase containing the organic substance and the organic contaminants. Typical organic contaminants include acrylonitrile prepared from propylene, methyl methacrylate prepared from acetone cyandihydrin, and methyl methacrylate prepared from acrylonitrile. The ammonium sulphate is readily crystallized from the aqueous phase.

Abstract: Growth of shaped crystals, such as silicon, germanium, garnet, sapphire and the like, using a crucible to contain a melt in conjunction with a wettable submerged projection extending above the level of the melt over which is formed a convex or raised meniscus of the melt by surface tension. A seed crystal is brought in contact with the meniscus and then drawn upwardly so that the melt of the meniscus crystallizes out and grows to the crystal lattice of the seed as a continuation thereof.

Abstract: A method of producing the single crystals of the gadolinium molybdate family having a high transmission and low threshold field, comprising the step of growing a single crystal from a melt of the gadolinium molybdate family by a crystal pulling technique, the step of cooling slowly the single crystal in a temperature range of from immediately below a melting point to a segregation temperature of .alpha. phase of the single crystal and the further step of cooling under such cooling conditions that the .alpha. phase is not segregated and the value of the threshold field of the single crystal is not made large in a temperature range of below the segregation temperature of the .alpha. phase.

Abstract: A process is provided for the recovery of chemicals, such as chlorides, sulfates, carbonates and borates of such alkali metals as sodium and potassium, among others, from underground brines associated with an ore body containing said chemicals, wherein the underground brine is pumped to the surface and confined over said ore body where it is concentrated by solar evaporation and the concentrated brine returned to an underground basin adjacent said ore body and stored for later removal by pumping for the subsequent recovery of chemicals therefrom. Thus, solar evaporation is used to produce the desired concentration of brine to optimize the subsequent recovery of chemicals therefrom, thereby resulting in substantial savings in overall energy costs.

Abstract: A crystallization vessel is provided which includes an elutriation column having an outlet at an upper end thereof and an inlet at a lower end thereof which inlet is in communication with a body of slurry contained therein. Flow regulating means associated with the elutriation column outlet enables the flow velocity within the column to be regulated for controlling the size of crystal particles removed from the slurry body through the elutriation column outlet. A movable baffle in the column is also provided for selectively varying the cross-sectional area of the column and thereby independently regulating the quantity of slurry removed from the slurry body through the elutriation column outlet. In this manner, both the size and quantity of crystal particles removed from the slurry body are independently regulated, thereby providing product crystals of improved size uniformity.

Abstract: An absorber-crystallizer tower is provided with improved means for spraying aqueous solution into a reactive gas to saturate the solution from which the product crystalizes and with improved means for removing scale from the crystal containing suspension which is formed. The apparatus has no scale sensitive internal surfaces and operates continuously without substantial scale build-up.

Abstract: An apparatus for growing crystals from hydrothermal solutions comprises a vertically extending autoclave having a crystallization zone in its top portion and a dissolution zone in its bottom portion. The autoclave is surrounded by a heat insulation layer, is provided with a system of heating elements and is enclosed in a thermostatically controlled chamber which is divided into vertically extending sections. Each section is provided with a heating and thermostatic control system so as to ensure the maintenance of constant and different temperature values in each section required to create and maintain the desired temperature fields in the crystallization and dissolution zones of the autoclave.

Abstract: Single crystals, useful as laser emission compounds, having the formula ARF.sub.4 wherein A is potassium, sodium, or lithium, and R is holmium, yttrium, erbium, or dysprosium are prepared by a direct congruent melt crystal growth process that yields crystals exhibiting substantially superior physical and chemical characteristics compared to those grown by conventional methods.

Abstract: In the purification of wet process phosphoric acid by solvent extraction, there is employed an organic solvent partially miscible with water, e.g. isobutanol. By using such a solvent containing about 40 to 50 % less than the saturation level of dissolvable water, the rate of extraction is improved and the formation of gels is avoided. It is preferred that the temperature during the extraction state be maintained substantially constant.

Abstract: A method and apparatus for positively introducing dopants into semiconductor crystals via crucible-free zone melting whereby a polycrystalline rod is mounted at opposite ends thereof in a housing which includes an annular induction heating coil surrounding a section of the rod for producing a melt zone at such section and a thin dopant source rod having a predetermined amount of dopant therein is controllably fed into the melt zone so that a positively determinable amount of dopant is provided in the recrystallized rod.

Abstract: The contact plate for mass-exchange apparatus consists of two disks facing each other with their end surfaces and capable of mutual rotation round the axis thereof. Each disk has one slit-like hole shaped as an Archimedean spiral so that when one disk rotates with reference to the other said holes overlap each other.

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: Voluminous precipitates or suspensions are contacted countercurrently with liquid purification or extraction agents that hold the continuously supplied precipitate or suspension in the upwardly flowing liquid in a kind of fluidized bed. A suitable apparatus is also described.

Abstract: A method for collecting a solid product from a liquid phase or liquid phase-gaseous phase feed stock. A solid forming zone is provided for accommodating the liquid phase or liquid phase-gaseous phase feed stock having a density greater than that of a liquid to be fed. A precipitation zone is provided at its lower portion with a feed port for feeding the liquid and a discharge port for taking out the solid product and communicating with the solid forming zone at its upper portion. The precipitation zone is provided therein with stirring means by which the solid product and liquid are contacted with each other countercurrently. The solid product is washed with the liquid and the density relation between the liquid phase and the liquid is reversed as the latter moves upwardly in the precipitation zone. Solid oxamide may be produced from cyanogen.

Abstract: A process for producing amethyst crystals which involves growing colourless quartz crystals by a hydrothermal method of a temperature drop in a high-pressure autoclave on crystalline quartz seed plates oriented parallel to pinacoid crystallographic planes {0001} or to planes inclined to said pinacoid planes at an angle of up to 15.degree. with the use of silica as a charge, said growing being effected from aqueous solutions of ammonium fluoride with a concentration of from 5 to 30% by weight and containing iron introduced into the autoclave in the form of its oxydic or hydroxydic compounds in an amount ranging from 5 to 30 g/l of the solution. Said growing of colourless quartz crystals is effected at a crystallization temperature within the range of from 150.degree. to 500.degree.C under a pressure of from 10 to 1,200 kg/cm.sup.2 and at a crystal growth rate of from 0.05 to 1.5 mm/day.

Abstract: A new self-cleaning salt dissolver construction which includes a special dissolving zone which supports the salt for dissolution while at the same time permitting the collection of sludge-impurities in the dissolving zone such that the sludge-impurities can be removed by a special cleaning operation when desired, without requiring the removal of the salt bed from the dissolver.