Tantalum fluorides

No available data was found on the precipitation from fluoride solutions of niobium and tantalum fluoride compounds containing tri- and tetravalent metals. [Pg.19]

The results available on the synthesis of niobium and tantalum fluoride compounds from aqueous solutions are in good correlation with the concept of... [Pg.19]

FERROELECTRIC PROPERTIES OF NIOBIUM AND TANTALUM FLUORIDE COMPOUNDS... [Pg.217]

Spontaneous polarization and non-linear optical effect in niobium and tantalum fluoride compounds... [Pg.223]

Density of melts containing niobium fluorides, 151 tantalum fluorides, 152, 165... [Pg.384]

Ta and Nb containing minerals, 4 Ta and Nb oxides dissolution, 258 Tantalum fluoride properties, 25 Tantalum extraction, 285-288... [Pg.388]

Neither calcium nor magnesium is used as the reducing agent in the production of tantalum by fluoride reduction. The intermediate used is potassium tantalum fluoride (K2TaF7), and the reducing agent is sodium. The choice of sodium is primarily guided by the need to produce tantalum in the powder form. The pertinent reaction is ... [Pg.424]

Gravimetric Methods.—The mixture of pentoxides of niobium and tantalum is redissolved in concentrated hydrofluoric acid and separated by Marignac s process (see p. 128) the potassium tantalum fluoride and potassium niobium oxyfluoride are then separately converted into the pentoxides as described above, and -weighed.1 This method has several disadvantages (1) The ratio of the solubilities of the two compounds on which the separation is based is only approximately 10 1, and the process is, therefore, necessarily inaccurate even when the recrystaflisation is repeated to a tedious extent the error approaches 1 per cent. (2) The concentration of the hydrofluoric add and of the potassium fluoride must be carefully controlled if the acidity is too low, an oxyfluoride of tantalum is precipitated if the acidity is too great, a normal fluoride of niobium is obtained. (3) Several platinum dishes are necessary. [Pg.130]

The estimation of small quantities of tantalum in niobium compounds is more difficult, and cannot be carried out colorimetrically. The usual method is to convert the material into the potassium double fluoride, and then to take advantage of the fact that a white precipitate of potassium tantalum oxyfluoride, K4Ta405F14 (see p. 132), is thrown down when a solution of potassium tantalum fluoride, KaTaF7, is boiled.7 Powell and Schoeller 8 find this test imperfect, and have modified the procedure (based on the differential hydrolytic dissociation of oxalo-niobic acid and oxalo-tantalic acid in the presence of tannin in slightly add solution) for the detection and estimation of traces of tantalum in niobium compounds. [Pg.131]

The hydrofluoric acid solution of niobic acid does not yield a precipitate on the addition of potassium fluoride (potassium niobium fluoride, K2NbF7, which is formed, being soluble in about 12-5 parts of water), whereas the hydrofluoric acid solution of tantalic add yields colourless, rhombic needles of potassium tantalum fluoride, K2TaF7 (which is soluble in about 150 parts of water under the same conditions), when treated with a saturated solution of potassium fluoride, carefully evaporated and cooled slowly. After removal of the tantalum, and with further concentration, any niobium present separates in pdates of potassium niobium oxyfluoride, K2Nb0F5.H20, if the hydrofluoric acid is not in excess, and in needles of potassium niobium fluoride, K2NbF7, if the hydrofluoric acid is in excess. [Pg.132]

The potassium tantalum fluoride first precipitated is a fusible substance. Its aqueous solutions on being boiled predpitate a very insoluble potassium tantalum oxyfluoride, 4KF.Ta2Os.2TaFs or K4Ta4OfiFu, as a white powder. This reaction is stated to constitute a sensitive test for tantalum.1... [Pg.132]

Aluminium alloys well with up to about 3-5 per cent, of tantalum, which has no effect, however, on the mechanical strength, ductility, and working properties of aluminium.3 Reduction of tantalum pentoxide by the thermite process yields hard, brittle alloys.1 A substance the composition of which corresponds with the formula TaAls has been obtained by reducing potassium tantalum fluoride, K2TaF7, with aluminium filings at a high temperature. It is described as an iron-grey crystalline powder, of density 7-02, which is scarcely attacked by acids.5... [Pg.183]

Tantalum Pentafluoride, TaFs, is the only known fluoride of tantalum, and has been successfully isolated by methods that avoid hydrolysis (1) Tantalum and fluorine are brought into reaction exactly as in the preparation of niobium pentafluoride.1 (2) Tantalum penta-chloride is treated in the cold with dry hydrofluoric add the hydrochloric acid liberated and excess of hydrofluoric add are evaporated oft, and the resulting tantalum pentafluoride is purified by redistillation in a platinum crucible between 300° and 400° C.2 (3) The double barium tantalum fluoride, 3BaF2.2TaF5, is very strongly heated in a platinum tube, one end of which is kept cold. ... [Pg.188]

Barium Tantalum Fluoride, 3BaF2.2TaF5 or Ba3Ta2F16, separates as a white, micro-crystalline precipitate from the action of barium chloride on a solution of tantalum pentoxide in slight excess of hydrofluoric acid. ... [Pg.189]

Copper Tantalum Fluoride, CuF2.TaF6.4H20 or CuTaF7.4H20, can be obtained in blue, transparent, rhombic crystals by the action of copper oxide on a solution of tantalum pentoxide in excess of hydrofluoric acid. It is very readily soluble in water.3... [Pg.190]

Lithium Tantalum Fluoride, LiF.TaFg.2HaO or LiTaF6.2HaO, is obtained in colourless, prismatic crystals when a solution of tantalum pentoxide in excess of hydrofluoric acid is treated with lithium carbonate.4... [Pg.190]

Rubidium Tantalum Fluoride, 2RbF.TaFB or RbaTaF is obtained in white needles similarly to the analogous potassium compound. It dissolves in 40 parts of water.3... [Pg.191]

Thallium Tantalum Fluoride, 2TlF.TaF5 or TlaTaF7, is obtained in glistening crystals by the action of thallium fluoride on tantalum pentoxide in hydrofluoric acid.1... [Pg.191]

Potassium Tantalum Oxyfluoride, 4KF.2TaFB.TaaOB or TaaOB. 2(2KF.TaFB).—(See under Potassium Tantalum Fluoride, 2KF.TaFB, on p. 190.) Two other potassium tantalum oxyfluorides have been reported, 2KF.TaOF3 2 and 8KF.TaOFs.s... [Pg.192]

See also in sourсe #XX -- [ Pg.3 , Pg.179 ]

See also in sourсe #XX -- [ Pg.3 , Pg.179 ]

See also in sourсe #XX -- [ Pg.3 , Pg.179 ]

See also in sourсe #XX -- [ Pg.3 , Pg.179 ]

See also in sourсe #XX -- [ Pg.3 , Pg.179 ]

See also in sourсe #XX -- [ Pg.3 , Pg.179 ]

See also in sourсe #XX -- [ Pg.3 , Pg.179 ]

See also in sourсe #XX -- [ Pg.318 ]

See also in sourсe #XX -- [ Pg.3 , Pg.179 ]

See also in sourсe #XX -- [ Pg.3 , Pg.179 ]

See also in sourсe #XX -- [ Pg.346 ]

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