RAMAN INVESTIGATION ON (TA2O5)(1-X)(TIO2)(X) SYSTEM AT DIFFERENT TEMPERATURES AND PRESSURES

Micro Raman spectra for (Ta2O5)(1-x)(TiO2)(x) reveal an induced Raman enhancement of the low frequency phonon modes for a critical TiO2 cont ent, x = 0.08. The temperature and pressure effects on these modes hav e also been studied. The Raman enhancement is shown to be associated w ith effects of the superstructure which is composed of TiO6 octahedra and Ta-O clusters. Pressure Raman scattering on (Ta2O5)(0.92)(TiO2)(0. 08) indicates that a phase transition occurs at similar to 6.22 Gpa. B ased on our Raman scattering studies, the origin responsible for the e nhanced dielectric constant in samples with TiO2, content, x = 0.08, h as been provided and discussed. (C) 1997 Elsevier Science Ltd.