A method for producing a fluoride fluorescent material comprises: preparing fluoride particles having a composition containing at least one element or ion A selected from the group consisting of alkaline metal elements and NH.sub.4.sup.+, at least one element M selected from the group consisting of Group-4 elements and Group-14 elements, Mn.sup.4+, and F, in which a molar ratio of A in 1 mol of the composition is 2, a total molar ratio of M and Mn.sup.4+ is 1, a molar ratio of Mn.sup.4+ is in a range of more than 0 and less than 0.2, and a molar ratio of F is 6; subjecting the fluoride particles to a first heat treatment at a temperature of 500? C. or more in an inert gas atmosphere; washing the first heat-treated fluoride particles with a washing liquid; and bringing the washed fluoride particles into contact with a fluorine-containing substance and subjecting the resulting fluoride particles to a second heat treatment at a temperature of 400? C. or more.

The invention provides disilenes, germasilenes and neopentatetrelanes, a method for the preparation thereof and use thereof.

A process for synthesizing a Mn.sup.4+ doped phosphor of formula I by electrolysis is presented. The process includes electrolyzing a reaction solution comprising a source of manganese, a source of M and a source of A. One aspect relates to a phosphor composition produced by the process. A lighting apparatus including the phosphor composition is also provided. A.sub.x[MF.sub.y]:Mn.sup.4+ (I) where, A is Li, Na, K, Rb, Cs, or a combination thereof; M is Si, Ge, Sn, Ti, Zr, Al, Ga, In, Sc, Hf, Y, La, Nb, Ta, Bi, Gd, or a combination thereof; x is the absolute value of the charge of the [MF.sub.y] ion; and y is 5, 6 or 7.

A process for synthesizing a Mn.sup.4+ doped phosphor of formula I by electrolysis is presented. The process includes electrolyzing a reaction solution comprising a source of manganese, a source of M and a source of A. One aspect relates to a phosphor composition produced by the process. A lighting apparatus including the phosphor composition is also provided. A.sub.x[MF.sub.y]:Mn.sup.4+ (I) where, A is Li, Na, K, Rb, Cs, or a combination thereof; M is Si, Ge, Sn, Ti, Zr, Al, Ga, In, Sc, Hf, Y, La, Nb, Ta, Bi, Gd, or a combination thereof; x is the absolute value of the charge of the [MF.sub.y] ion; and y is 5, 6 or 7.

The present invention relates to a process for producing a composite-fluoride fluorescent material represented by the general formula A.sub.2MF.sub.6:Mn.sup.4+ (wherein A is at least one alkali metal element including K; M is one or more metallic elements including at least Si or Ge and selected from among Si, Ge, Sn, Ti, Zr, and Hf; F is fluorine; and Mn is manganese). With the production process, it is possible to obtain a fluorescent material which is high in absorptance, internal quantum efficiency, and external quantum efficiency and has excellent optical properties.

In particular, in alternative embodiments, the invention provides for a method to recover silicofluoride and phosphate species from wastewaters, or barometric condenser waters, that are typically utilized in wet-process phosphoric acid facilities. The species are recovered via a continuous ion exchange approach that allows for economic recovery of the materials and especially with the silicofluoride component allows for the production of valuable industrial materials such as hydrofluoric acid and other fluoride salts as well as industrial-grade precipitated silica materials. Return of the treated waste water to the phos-acid plant allows for optimization of reagent usage.

In particular, in alternative embodiments, the invention provides for a method to recover silicofluoride and phosphate species from wastewaters, or barometric condenser waters, that are typically utilized in wet-process phosphoric acid facilities. The species are recovered via a continuous ion exchange approach that allows for economic recovery of the materials and especially with the silicofluoride component allows for the production of valuable industrial materials such as hydrofluoric acid and other fluoride salts as well as industrial-grade precipitated silica materials. Return of the treated waste water to the phos-acid plant allows for optimization of reagent usage.

The present invention relates to a method for producing a hexafluoromanganate(IV), said method being characterized by comprising: inserting an anode and a cathode into a reaction solution that contains a compound containing manganese having an atomic valence of less than 4 and/or manganese having an atomic valence of more than 4 and hydrogen fluoride; and then applying an electric current having an electric current density of 100 to 1000 A/m.sup.2 between the anode and the cathode. According to the present invention, it becomes possible to produce a hexafluoromanganate(IV) in which the content ratio of manganese having an atomic valence of 4 is high and the contamination with oxygen is reduced and which has high purity. When a complex fluoride red phosphor is produced using the hexafluoromanganate(IV) as a raw material, the phosphor produced has high luminescence properties, particularly high internal quantum efficiency.

A process for preparing a Mn.sup.4+ doped phosphor of formula I
A.sub.x[MF.sub.y]:Mn.sup.+4I
includes contacting a mixture of a compound of formula A.sub.x[MF.sub.y], a compound of formula AX, and a Mn.sup.+n source comprising a fluoromanganese compound, with a fluorine-containing oxidizing agent in gaseous form, at an elevated temperature, to form the Mn.sup.4+ doped phosphor;
wherein A is Li, Na, K, Rb, Cs, or a combination thereof; M is Si, Ge, Sn, Ti, Zr, Al, Ga, In, Sc, Hf, Y, La, Nb, Ta, Bi, Gd, or a combination thereof; X is F, Cl, Br, I, HF.sub.2, or a combination thereof; x is the absolute value of the charge of the [MF.sub.y] ion; y is 5, 6 or 7; and n is 2, 3, or 4.

A process for preparing a Mn.sup.4+ doped phosphor of formula I
A.sub.x[MF.sub.y]:Mn.sup.+4I
includes contacting a mixture of a compound of formula A.sub.x[MF.sub.y], a compound of formula AX, and a Mn.sup.+n source comprising a fluoromanganese compound, with a fluorine-containing oxidizing agent in gaseous form, at an elevated temperature, to form the Mn.sup.4+ doped phosphor;
wherein A is Li, Na, K, Rb, Cs, or a combination thereof; M is Si, Ge, Sn, Ti, Zr, Al, Ga, In, Sc, Hf, Y, La, Nb, Ta, Bi, Gd, or a combination thereof; X is F, Cl, Br, I, HF.sub.2, or a combination thereof; x is the absolute value of the charge of the [MF.sub.y] ion; y is 5, 6 or 7; and n is 2, 3, or 4.