Formation of crystalline titanium(IV) phosphates from titanium(III) Solutions

Crystalline phases of titanium(IV) phosphate have been obtained from titanium(III) chloride in phosphoric acid solutions. The α-titanium phosphate synthesis is possible at low temperature (60–80 °C). γ-Titanium phosphate is obtained by reflux with very concentrated phosphoric acid in 3–5 hours by oxidation with O2. The influence in these reactions of several factors (concentration of reagents, molar ratio P:Ti in the reaction mixture, temperature and reaction time) was studied. The α-titanium phosphate formation takes place in several steps through the sequential formation of amorphous titanium(IV) phosphate, γ-titanium phosphate and/or a semicrystalline titanium(IV) hydroxophosphate, Ti(OH)2(HPO4) · H2O.