Structural and dielectric properties of (Ba1−xSrx)0.93Na0.07Ti0.93Nb0.07O3 ceramics
Résumé
(Ba1−xSrx)0.93Na0.07Ti0.93Nb0.07O3 ceramics with different compositions (x = 0.15; 0.2; 0.25; 0.4) were synthesized by a conventional solid-state reaction at 1470 °C for 2 h (h). Phase purity, structure and crystallinity were investigated with X-ray diffraction at room temperature, showing pure phases with tetragonal symmetries for (x = 0.15, 0.2) and cubic for (x = 0.25, 0.4). The real part of the relative dielectric permittivity ε′rm exhibited a sharp peak with no frequency dependence, which revealed a ferroelectric relaxor behavior for all compositions with a diffuse phase transition and frequency dispersion. The evolution of the Raman spectra, at room temperature, shows an introduction of disorder in this composition, thus favoring a ferroelectric relaxor behavior.