Ammonium Diuranate, (NH₄)₂U₂O₇

Ammonium Diuranate, (NH₄)₂U₂O₇, is obtained as a yellow voluminous precipitate when solutions of uranyl salts are treated with ammonia. It is prepared commercially by boiling a solution of sodium uranyl carbonate with ammonium sulphate, or by boiling a solution of sodium diuranate with concentrated ammonium chloride solution. It is a deep yellow powder, which may be dried at 100° C.; at higher temperatures it yields urano-uranic oxide. When fused with ammonium chloride, uranous oxide is formed. It is known commercially as "uranium yellow" (see also sodium diuranate) and is used in making fluorescent "uranium glass." It is insoluble in ammonium hydroxide solution, and this fact is sometimes made use of in the analytical separation of uranium.