Barium Niobate

The compound, 7BaO.6Nb₂O₅.18H₂O, forms a thick white precipitate when the corresponding sodium salt is treated with barium chloride.

A niobooxalate, 5BaO.Nb₂O₅.10C₂O₃.20H₂O, is precipitated by the action of a solution of a barium salt on the potassium salt, 3K₂O.Nb₂O₅. 6C₂O₃, or by digesting a mixture of barium oxalate and hydrated niobic acid with oxalic acid. It forms crystals insoluble in water, hydrochloric acid, and nitric acid. By hot acids it is decomposed, giving niobic acid. It is soluble in warm oxalic acid solution.