Tantalate powders

C. H. Lu and S. K. Saha, Colloid emulsion of nanosized strontium bismuth tantalate powder,... 

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. 

Agulyanskaya et al. [507] investigated the impact of fluorine content on the particle size of niobium and tantalum oxides and powdered lithium niobate and tantalate prepared from the oxides. It was shown that fluorine concentrations lower than 10"2% wt. do not influence particle size and result in a set minimum particle size. This concentration range was referred to as being non-... 

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-... 

Synthesis of niobates and tantalates of alkaline metals at high temperatures may result in the products with unintended stoichiometry because of high volatility of alkaline metal (especially lithium) oxides. Therefore, their synthesis in the form of efficiently sintering powders presents a serious problem. Films of alkaline niobates and tantalates can find wide range of applications in acousto- and optoelectronics and are usually prepared by rf-sputtering techniques, also giving rise to stoichiometry problems. 

DItantalum pentaoxide EINECS 215-238-2 Tantalic acid anhydride Tantalum oxide Tantalum oxide (TaaOs) Tantalum oxide dusts Tantalum penta oxide Tantalum pentoxide. Used in production of tantalum, tantalum carbide optical glass piezoelectric and laser applications dielectric layers in electronic circuits. White powder insoluble in H2O, soluble in HE LDso (rat orl) = 8000 mg/kg. Atomergic Chemefa/s Cabof Carbon Ltd. Cerac Sigma-Akirich Fine Chem. 

Even a portion of fluorido-oxido-tantalates with different counter cations was investigated here, the focus being given to a more detailed investigation of the selected compounds - KjTaOF and K3Ta02F4 - based on X-ray single crystal analysis. X-ray powder diffraction, secondary ionised mass spectroscopy (SIMS) and XPS spectroscopy. The available structural data for both compounds are summarised in Table 3.3.1. 

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