Zirconium Fluoride, ZrF₄

Zirconium Fluoride, ZrF₄, is formed when the dioxide is gently heated with twice its weight of ammonium difluoride, and can also be obtained by the action of anhydrous hydrofluoric acid on the tetrachloride. It sublimes in small, highly refractive prisms having a density of 4.4333; 110 c.c. of cold water dissolve 1.388 grams of ZrF₄, and at 50° C. hydrolysis causes the separation of the hydroxide from the solution. On evaporating a hydrofluoric acid solution of the fluoride, triclinic tablets of the hydrate ZrF₄.3H₂O crystallise out. Thus zirconium fluoride possesses some distinctly saline properties. It combines with liquid ammonia to form the compound 5ZrF₄.2NH₃ (Wolter).