Abstract: An object of the present invention is to provide a method for purifying a highly pure niobium compound and/or tantalum compound, the method enabling the purification of a highly pure niobium compound and tantalum compound in a simplified manner at a low cost. The object is met by providing a method comprising adding an organic solvent to an aqueous solution containing a niobium compound and/or tantalum compound together with impurities, and then performing extraction via the solution. A niobium compound and/or tantalum compound dissolved in a solution is allowed to precipitate, and said aqueous solution is obtained by dissolving the precipitate in water.

Abstract: It is aimed at providing a fluoride crystal growing method capable of controlling a shape of the crystal by a micro-pulling-down method. Fluoride crystals in shapes depending on purposes, respectively, can be grown by adopting carbon, platinum, and iridium as crucible materials adaptable to fluorides, respectively, and by designing shapes of the crucibles taking account of wettabilities of the materials with the fluorides, respectively.

Abstract: An apparatus for producing a fluoride crystal, which has a chamber, a window material and the like capable of dealing with the fluoride, is equipped with facilities necessary for high vacuum evacuation, and uses a crucible in which the capillary portion of the hole formed in the bottom thereof is so controlled for a seed crystal and a molten material to be easily contacted to each other; and a method for producing a fluoride crystal comprising using the apparatus. The apparatus allows the production of a single crystal of a fluoride having high quality in a extremely short time with stability.

Abstract: It is aimed at providing an analysis method of impurities (color centers) in fluoride, capable of extremely simply analyzing impurities (color centers) in fluoride. It is also aimed at providing an analysis method of impurities (color centers) in fluoride, for enabling evaluation of an effect by addition of a scavenger, before obtainment of a final single crystal. There are detected absorption peaks and the like of formed color centers and the like, by irradiating X-rays to an obtained fused material, and by measuring transmittances thereof before and after the irradiation. Based thereon, there are optimized melt conditions of a scavenger and the like, thereby enabling growth of a high purity molten raw material suitable for growth of a single crystal less in X-ray damage.

Abstract: The present invention provides a method enabling the high purification of a niobium compound and/or tantalum compound in a simplified manner at a low cost. This is accomplished by providing a method enabling the high purification of a niobium compound and/or tantalum compound comprising the steps of preparing a solution containing niobium and/or tantalum, allowing a precipitate comprising niobium and/or tantalum to develop, separating the precipitate by filtration from the filtrate, converting the precipitate to a liquid melt or taking the filtrate, and separating a niobium compound from a tantalum compound or vice versa by utilizing the difference in solubility to the solvent between the niobium compound and the tantalum compound.

Abstract: A surface treatment solution for finely processing a glass substrate containing multiple ingredients is used for the construction of liquid crystal-based or organic electroluminescence-based flat panel display devices without invoking crystal precipitation and/or increasing surface roughness. An etching solution of the invention contains, in addition to hydrofluoric acid (HF) and ammonium fluoride (NH4F), at least one acid whose dissociation constant is larger than that of HF. The concentration of the acid in the solution can advantageously be adjusted to maximize the etching rate.

Abstract: A scintillator, characterized in that it comprises crystals of Pr1-xCexF3 [wherein 0<x<0.5]. It emits a light in ultraviolet and visible regions when it is irradiated with a light or a radiation. The scintillator uses a material which exhibits improved performance with respect to the strength in light emission and to the speed in attenuation, and further is relatively easy in the growth of its crystal.

Abstract: A method for reducing oxygen and carbon components in high-purity fluoride such as calcium fluoride and barium fluoride (a high-purity fluoride that is not limited to calcium fluoride and barium fluoride), or in rare-earth fluorides such as ytterbium fluoride and cerium fluoride used for an optical fiber, a coating material, and so on. The oxygen and carbon components contained in the high-purity fluoride are reduced by a fluorine gas treatment.

Abstract: Provided is a method for purifying a quaternary alkyl ammonium salt enabling the obtainment of a particulate quaternary alkyl ammonium salt having a low water content at a high yield which is suitably used as an electrolyte in an electrolytic solution. The method for the purification of a quaternary alkyl ammonium salt comprises dispersing a quaternary alkyl ammonium salt to be purified into an organic solvent to allow it to form a suspension there. The alkyl groups constituting the quaternary alkyl ammonium salt have 1 to 5 carbon atoms each. The quaternary alkyl ammonium salt to be purified is dispersed into the organic solvent to make a suspension, and then the particles are washed with an alcohol solvent.

Abstract: The present invention provides a method enabling the high purification of a niobium compound and/or tantalum compound in a simplified manner at a low cost. This is accomplished by providing a method enabling the high purification of a niobium compound and/or tantalum compound comprising the steps of preparing a solution containing niobium and/or tantalum, allowing a precipitate comprising niobium and/or tantalum to develop, separating the precipitate by filtration from the filtrate, converting the precipitate to a liquid melt or taking the filtrate, and separating a niobium compound from a tantalum compound or vice versa by utilizing the difference in solubility to the solvent between the niobium compound and the tantalum compound.

Abstract: In order to provide a method for producing lithium hexafluorophosphate capable of producing lithium hexafluorophosphate of a higher purity than in the related art without the necessity for after-treatment for removal of impurities, a method is characterized by filtering lithium hexafluorophosphate coexisting with a solvent and then carrying out after-filtering drying in a gas atmosphere containing PF5.

Abstract: A method for removing calcium from water containing a high concentration of calcium bicarbonate, permitting a reduction of the calcium bicarbonate equivalent to 200-500 ppm calcium to the level in accordance with the water quality standards for industrial use, not by a method using a large amount of heat and power as heating and deairing, but by a simple chemical treatment. Calcium hydroxide is added to waste water containing a high concentration of calcium in a form of calcium bicarbonate for making them react with each other, and removing calcium by fixing it to calcium bicarbonate.

Abstract: The present invention provides a method for purifying a niobium compound and/or tantalum compound in a simplified manner at a low cost. This is accomplished by providing a method for purifying a niobium compound and/or tantalum compound whereby a niobium compound and/or tantalum compound dissolved in a solvent is allowed to precipitate to be isolated.

Abstract: An object of the present invention is to provide a method for purifying a highly pure niobium compound and/or tantalum compound, the method enabling the purification of a highly pure niobium compound and tantalum compound in a simplified manner at a low cost. The object is met by providing a method comprising adding an organic solvent to an aqueous solution containing a niobium compound and/or tantalum compound together with impurities, and then performing extraction via the solution. A niobium compound and/or tantalum compound dissolved in a solution is allowed to precipitate, and said aqueous solution is obtained by dissolving the precipitate in water.

Abstract: A method for purifying tungsten hexafluoride of high purity, capable of producing tungsten hexafluoride of higher purity than that of the related art, readily and at a low cost. A method for purifying tungsten hexafluoride of high purity, characterized in that tungsten hexafluoride containing molybdenum hexafluoride as an impurity, makes contact with a layer, in which a metal or an alloy is packed, containing at least one of molybdenum, tungsten, copper, nickel, iron, cobalt, zinc, titanium, aluminum, calcium, and magnesium at a temperature ranging from 0° C. to 100° C.

Abstract: A method of purifying lithium hexafluorophosphate that allows to purify lithium hexafluorophosphate, useful as lithium secondary cell electrolyte, organic synthesis medium or the like, to an extremely high purity is provided. Lithium hexafluorophosphate containing harmful impurities such as oxyfluoride, lithium fluoride is purified by adding phosphoric chloride. The purification is performed in the presence of phosphoric chloride and hydrogen fluoride of the quantity equal or superior to the equivalent amount for reacting them, and then by converting lithium fluoride lithium hexafluorophosphate with generated phosphor pentafluoride.

Abstract: An etching agent which can etch insulating film with high speeds without damaging the resist pattern, provide realistic throughput when the insulting film etching process in the semiconductor manufacturing process is replaced with the single wafer processing etching treatment method, and prevent roughness on the surface of the semiconductor after etching.

Abstract: The present invention provides a micromachining surface treatment material for and a surface treatment method that suppress widening of the diameter of contact holes when removing a natural oxidation layer arising at bottom sections of the contact holes. The micromachining surface treatment material contains less than 0.1% hydrofluoric acid, and more than 40% by weight but less than or equal to 47% by weight of ammonium fluoride. Also, a surfactant is contained therein in an amount from 0.0001 to 0.1 % by weight.

Abstract: The present invention provides a micromachining surface treatment material for and a surface treatment method that suppress widening of the diameter of contact holes when removing a natural oxidation layer arising at bottom sections of the contact holes. The micromachining surface treatment material contains less than 0.1% hydrofluoric acid, and more than 40% by weight but less than or equal to 47% by weight of ammonium fluoride. Also, a surfactant is contained therein in an amount from 0.0001 to 0.1% by weight.

Abstract: An etching treatment agent which can etch insulating film with high speeds without damaging the resist pattern, provide realistic throughput when the insulting film etching process in the semiconductor manufacturing process is replaced with the single wafer processing etching treatment method, and prevent roughness on the surface of the semiconductor after etching.