Sodium tantalates

Simple ABO compounds in addition to BaTiO are cadmium titanate [12014-14-17, CdTiO lead titanate [12060-00-3] PbTiO potassium niobate [12030-85-2] KNbO sodium niobate [12034-09-2], NaNbO silver niobate [12309-96-5], AgNbO potassium iodate [7758-05-6], KIO bismuth ferrate [12010-42-3], BiFeO sodium tantalate, NaTaO and lead zirconate [12060-01 -4], PbZrO. The perovskite stmcture is also tolerant of a very wide range of multiple cation substitution on both A and B sites. Thus many more complex compounds have been found (16,17), eg, (K 2 i/2) 3 ... 

Tantalum can be separated from niobium by recrystallization of the double potassium fluorides. In the commercial process the ore is fused with caustic soda. The insoluble sodium niobate, sodium tantalate, and... 

In addition to potassium hydrogen sulphate and sodium hydrogen sulphate8 for opening up the ore, potassium carbonate,9 sodium peroxide, and alkali hydroxides 10 have been employed. The use of potassium hydroxide is preferred in the case of a high-grade ore of low titanium content 11 it has the advantage over sodium hydroxide that potassium tantalates are soluble in solutions which contain excess of the alkali, whereas sodium tantalates are insoluble. 

Ammonium Tantalate, (NH4)a0.3Ta205.5H20, is obtained as a flocculent precipitate by the addition of ammonium chloride to a solution of 4 8 sodium tantalate.2 An ammonium potassium tantalate, (NH4)20.K20.4Ta205.5Ha0, has also been obtained by the same reaction, using potassium tantalate. 

Sodium Tantalales.—4 3 Sodium tantalate, 4Na20.8Ta206.25H20, is prepared by fusing tantalum pentoxide with caustic soda in a silver crucible excess of caustic soda is removed by washing with water, and the residue is crystallised from hot water. Another method consists in adding a concentrated solution of sodium chloride to the aqueous extract from a fused mixture of tantalum pentoxide and potassium carbonate, when the salt separates as a dense, micro-crystalline powder. It forms six-sided plates, a c=l 1-0167. It loses most of its water of crystallisation between 105° and 110° C., but the remainder (apparently five molecules) appears to be water of constitution, as its removal takes place only at much higher temperatures, with decom-... 

Tantalum metal also forms an amorphous sodium tantalate layer with a graded structure [45] on treatment with a 0.5 M NaOH solution at 60°C for 24h [46] and heat treatment at 300°C for 1 h [47]. The thus-treated tantalum metal also forms a bone-like apatite layer on its surface in an SBF as well as in the living body, and bonds to living bone [48]. 

Sodium Tantalate. NaTa03 a ferroelectric compound having the ilmenite structure at room temperature the Curie temperature is approx. 475°C. Of potential interest as a special electroceramic. 

K. Shimura, S. Kato, T. Yoshida, H. Itoh, T. Hattori and H. Yoshida, Photocatalytic steam reforming of methane over sodium tantalate, J. Phys. Chem. C, accepted. 

Fluor-jod, n. iodine fluoride, -kalium, n. potassium fluoride, -kalzium, n. calcium fluoride, -kiesel, m. silicon fluoride, -kie-selsaure,/. fluosilicic acid, -kohlenstoff, m. carbon fluoride, -lithium, n. lithium fluoride. -metall, n. metallic fluoride, -natrium, n. sodium fluoride, -phosphat, n. fluophosphate. -phosphor, m. phosphorus fluoride, -salz, n. fluoride, -schwefel, m. sulfur fluoride, -selen, n. selenium fluoride, -silber, n. silver fluoride, -silikat, n. fluo-silicate. -silizium, n. silicon fluoride, -sili-ziumverbindung, /. fluosilicate. -tantal-sMure, /. fluotantalic acid, -tellur, n. tellurium fluoride, -titan, n. titanium fluoride, -toluol, n. fluorotoluene, fluotoluene. 

Tantalum powder is produced by reduction of potassium heptafluoro-tantalate, K2TaF7, dissolved in a molten mixture of alkali halides. The reduction is performed at high temperatures using molten sodium. The process and product performance are very sensitive to the melt composition. There is no doubt that effective process control and development of powders with improved properties require an understanding of the complex fluoride chemistry of the melts. For instance, it is very important to take into account that changes both in the concentration of potassium heptafluorotantalate and in the composition of the background melt (molten alkali halides) can initiate cardinal changes in the complex structure of the melt itself. 

A method of separation which avoids the preparation of the double fluorides consists in fusing the mixed niobic and t an tali c acids with sodium carbonate and nitrate, the product is digested with warm water and a current of carbon dioxide is passed through the solution. It is claimed that only tantalic acid is precipitated.5 This process has, however, been the subject of adverse criticism.6 Partial separation of niobium from tantalum can be effected by warming the mixed, freshly precipitated, hydrated oxides with a mixture of hydrogen peroxide and hydrochloric acid the niobium dissolves readily, while the tantalum dissolves only sparingly.7... 

Barium Tantalate, 4Ba0.3Ta205.6H20, results from the action of a barium salt in solution on a solution of 4 3 sodium or potassium tantalate. ... 

See l-terf-Butyl-3-(lV-terf-butyl-2-lithaminoethyl)imidazol-2-y]idene See Sodium trisO/1 naphthalene)tantalate(l-)... 

Monophosphate tungsten bronzes with pentagonal tunnels NASICON = Sodium super ionic conductor NLO = Nonlinear Optical PLZT = Lead lanthanum zirconium titanate PZT = Lead zirconium titanate SBT = Strontium Bismuth Tantalate, SrBi2Ta209 SOFC = Solid oxide fuel cell TTB = Tetragonal tungsten bronze YAG = Yttrium iron garnet 3D = Three-dimensional TEOS = Tetraethylorthosilicate. 

Tantalates are numerous, and form important ores of tantalum. Of these the most important is tantalite, which is ferrous meta tantalate, Fe(Ta08)2. These salts are all insoluble in water. Both ortho- and pyro-tantalates are known. In addition some important salts are derivatives of the hypothetical hexa-tantalic acid, H8Ta 0,j, whose sodium and potassium salts are soluble in water. 

Cesium nitrate Lithium niobate Lithium tantalate Lithium sodium sulfate Tourmaline... 

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