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.