On the synthesis of alpha-zirconium phosphate

Crystalline alpha-zirconium phosphate, Zr(HPO4)(2). H2O, was obtained by di rect precipitation of soluble salts of zirconium(IV) with phosphoric acid. The fresh compound transforms, by hydrolysis, into amorphous or semicrystal line hydroxophosphates with a P/Zr molar ratio of less than two. These fact s contradict the formation mechanism of zirconium phosphates admitted by re searchers for over more than 40 years. The materials are characterized by c hemical, textural, and thermal analysis, powder X-ray diffraction, and scan ning electron microscopy.