X-ray diffraction, dielectric and Raman studies of the Ba1-xNaxTi1-x(Nb1-ySby)xO3 ceramics

Ba1-xNaxTi1-x(Nb1-ySby)(x)O-3 (BNTNSO) ceramics with compositions (x=0.05; y=0; 0.10; 0.20 and 0.30) have been prepared by conventional solid-state method and sintered in the temperature range 1350-1400 degrees C. Phase purity and structure are investigated using X-ray diffraction (XRD) data. The structural study showed that our synthesized compounds are single phase and crystallize in the tetragonal system with P4mm space group at room temperature. Based on a phenomenological model, dielectric and Raman properties of BNTNSO compounds have been explored. Referring to this model, dielectric properties of ceramics have been investigated in broad ranges of temperature (100-500 K) and frequency 1-10(3) kHz). The dielectric permittivity evolution as a function of temperature and frequency has exhibited a classical ferroelectric character for 0 <= y <= 0.20 and a relaxor type behavior for y=0.30. The investigation of Raman spectra as a function of temperatures and compositions, confirmed the dielectric behavior. These results indicate that the y=0.20 composition is of extreme significance as far as its technological and industrial applications are concerned, which refers basically to its interesting physical properties and environmentally friendly characters, especially as its transition temperature is equal to the room temperature. The used samples show that the substitution of Nb by Sb favors and maintains the relaxor characters without changing the transition temperature.