Formation and Sintering of TiO2 (Anatase) Solid Solution in the System TiO2-SiO2

In the TiO₂-SiO₂ system, anatase solid solutions (ss) containing up to similar/congruent ～15 mol% SiO₂ are formed in the as-prepared state by the hydrazine method. The lattice parameters a and c decrease linearly from 0.3785 to 0.3776 nm and from 0.9514 to 0.9494 nm, respectively, with increased SiO₂ content. At high temperatures, the solid solutions by transformation decompose into rutile and amorphous SiO₂. The anatase(ss) powders have been characterized for particle size and surface area. They consist of very fine particles (7-25 nm). Surface areas at low temperatures are very high and do not drop below 60 m²/g at 1000°C. Nanostructured anatase(ss) ceramics, with greaterthan/equal to 99.5% of theoretical density and an average grain size of 72 nm, have been fabricated by hot isostatic pressing for 1 h at 850°C and 196 MPa. Their mechanical and electrical properties have been examined.