Zirconium Phosphates

Zirconium orthophosphate is formed as a gelatinous precipitate when a phosphate solution is added to a solution of a zirconium salt. The compound ZrO₂.P₂O₅ or ZrP₂O₇, zirconium pyrophosphate, is obtained crystalline when zirconia is fused with metaphosphoric acid; and 2ZrO₂.P₂O₅ is formed in cubical or octahedral crystals when hydrated zirconia is heated with syrupy phosphoric acid. Various double phosphates of zirconium and the alkali metals have been prepared by Troost and Ouvrard by melting zirconium oxide, phosphate, or chloride with an alkali phosphate.