Coprecipitation of titanium(IV) and Iron(III) complex salts from peroxide-fluoride solutions

Because the salts (NH 4 ) 3 TiO 2 F 5 and (NH 4 ) 3 FeF 6 are isostructural, precipitation of the titanium peroxy salt from the (NH 4 ) 2 TiF 6 -(NH 4 ) 3 FeF 6 -NH 4 F-H 2 O 2 system is accompanied by crystal-chemical substitution of ions. As a result of partial peroxolysis, the iron salt coprecipitates with ammonium peroxypentafluorotitanate. If the degree of precipitation is higher than 20%, TiO 2 samples of high whiteness can be prepared from the hydrolysis product isolated from such solutions, after annealing at 850°C.