Ammonium tantalate

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. 

The chemical interaction of lithium tantalate with molten ammonium hydrofluoride can be represented as follows ... 

Addition of ammonium hydroxide or ammonium sulphide to solutions of niobic acid and tantalic acid in mineral acids reprecipitates the niobic and tantalic acids, which may, however, retain some of the ammonia. This test does not distinguish between niobium and tantalum, and it does not proceed in the presence of tartaric acid. 

The reaction of phosphorus pentachloride with ammonium chloride is tantalizingly complex and has been the subject of numerous investigations (21). Cyclic oligomers and linear products are formed, and... 

Exfoliation of the perovskite related layer structures is more difficult than for the clays and acid phosphates discussed earlier but can be achieved by intercalation of large bulky amines. Treacy etal. reported that the layered perovskite HCa2Nb30io could be made to form unilamellar sheets by first intercalation of an amine polyether. Spontaneous exfoliation of the layers occurs on subsequent exposure of the intercalated phase to a suitable solvent. Exfoliation techniques have been extended to other systems using tetra(n-butyl)-ammonium hydroxide (TBAOH) by Mallouk and others. A number of examples of the protonated layered perovskite phases that intercalate bases have been exfoliated. The Dion-Jacobson phases typically exfoliate to form plates but others including Ruddlesden-Popper tantalates curl to form tubular scrolls . Part of the interest in these single layer dispersions arises from their use as building blocks in the layer-by-layer self-assembly of thin films. Single layers derived from exfoliated perovskites can be attached to or alternately stacked with polycationic layers to produce thin films. Tiled monolayer structures and multilayer perovskite heterostructures result from the self-assembly. 

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