Potassium tantalates

Potassium tantalate, KTaOs, has a similar degree of band bending (flat band potential of -0.2 V) but its band gap is even larger (3.5 eV) (20). 

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. 

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. ... 

IMkium Tantalate, 7Li2O.5Ta2O5.40H2O, is precipitated in six-sided plates when lithium hydroxide solution is added to a solution of 7 5 potassium tantalate.10... 

Boddy P. J., Kahng D. and Chen Y. S. (1968), Oxygen evolution on potassium tantalate anodes , Electrochim. Acta 13, 1311-1328. 

Fowler 1991). Insoluble species of tantalum, administered orally to rats, are poorly absorbed from the gastrointestinal tract, with total excretion accounted for in the feces. Ta administered orally to rats as soluble potassium tantalate was rapidly excreted almost exclusively via the fecal route less than 2% of the dose was retained after 1 day (Fleshman etal. 1971). More than 96% of the administered dose was excreted after 3 days, and less than 0.5% was recovered in urine after 7 days, although more than 97% of the total dose had been excreted. After absorption, Ta was primarily localized in the bone compartment, which retained over 40% of the total body burden after 14 days, and in the kidneys (Fleshman et al. 1971). The biological half life of the soluble, short-lived radionuclide (tj2 = 9.3 min) Ta given as Ta-chloride or Ta-oxide to dogs via intravenous administration was 190 min, with 78% of the Ta being found in the plasma ( 33% with the plasma protein fraction) and the remainder in red blood cells (Wilson etal. 1987). The distribution of soluble Ta administered intravenously to mice demonstrated Ta accumulation primarily in kidney (17% of the dose), followed by liver (9%) and blood (8.5%) (Wilson et al. 1987). 

Potassium tantalate. 440-444, 466f Pressure dependence absorption peak, band gap, 226... 

Perovskites and related compounds Barium titanate Lead titanate Potassium niobate Potassium tantalate niobate Lithium niobate Lithium tantalate Barium titanium niobate Ba-Na niobate ( Bananas )... 

Alternate method The same salt is obtained by treatment of a hot potassium tantalate solution with hot aqueous NaOH. 

A. B. Ellis, S. W. Kaiser, and M. S. Wrighton, Semiconducting potassium tantalate electrodes. Photoassistance agents for the efficient electrolysis of water, J. Phys. Chem. 80 (1976) 1325-1328. 

Potassium tantalate niobate KTai. b 3 KTN Kyropoulos technique Top seed solution growth... 

Potassium tantalate-niobate [K(Ta Nbi jc)03, KTN] is one of the ferroelectric materials with the perovskite structure, and is a sohd solution of potassium tantalate (KTaOs) and potassium niobate (KNbOs). The Ciuie temperature of KTN for the cubic to tetragonal transition varies with Ta/Nb ratio, and is lowered with increasing Ta substitution (Triebwasser, 1959). The ferroelectric properties of KTN, therefore, can be controlled by the Ta/Nb ratio. The nonferroelectric cubic phase of KTN atx= 0.65 is known to show photorefractive effect based upon a large quadratic electro-optic coefficient at room temperature (Gausic, 1964 Orlowski, 1980). 

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