Structural transformation in (Ta2O5)1−x(TiO2)x ceramics Original Research Article

Bulk (Ta2O5)1−x(TiO2)x ceramics for x=0.05, 0.08, and 0.11 were prepared by the conventional solid state reaction technique and the temperature dependent Raman scattering in the range 70–1173 K was used to study the structural transformations in them. The lowest frequency phonon modes, at about 35–38 cm−1, in these ceramics were assigned as Ta–Ti vibrations originating from the interaction between TiO6 octahedra and TaOn5−2n or Ta6O12+6 clusters. Raman spectra exhibited a softening of this mode with increasing temperature, followed by a structural transformation. A structural transition from triclinic to monoclinic phase was observed in the ceramics at about 360, 450, and 540°C for compositions x=0.05, 0.08, and 0.11, respectively.