The Study of Structure and Transitional Phases in Ba0.95Bi0.05Ti1-XFexO3 Ceramics Synthesized by Solid State Route

The structural and dielectric properties of iron and bismuth co-substituted BaTiO3 ceramic with the formula: Ba0.95Bi0.05Ti1-xFexO3 for x=0.00 to 1.00, synthesized by solid state route, were characterized. The X-ray diffraction results showed a tetragonal phase for x=0.00. While for x=0.40 to 0.80 we observed a coexistence of tetragonal, hexagonal and pseudo-cubic phases. At x= 1.00 only the pseudo-cubic phase is present and the other phase disappeared. The Raman results indicated the existence of tetragonal band for x≤0.40, and an appearance of characteristic bands of Fe3+ ions for Fe content of higher than 0.4. The SEM micrographs showed an increase in grain size with the increase of Fe content and it reached a maximum at x=0.40. The Mossbauer spectroscopy indicated that the samples are paramagnetic at room temperature and that the Fe is oxidized under Fe3+ with no existence of Fe2+ or Fe4+ ions. The temperature dependence of dielectric permittivity was investigated in the frequency range from 20 Hz to 2 MHz. The results showed three dielectric relaxation phase transitions from a rhombohedral ferroelectric to orthorhombic ferroelectric (TR-O) then to a tetragonal ferroelectric phase (at TO-T), and finally to cubic paraelectric at the Curie temperature (TC). In addition, the temperature of phase transition shifted to the lower temperature with the increase of Fe content for all the phase transitions. an‎d the maximum of dielectric permittivity increased for TR-O while for TT-O and Tm phases transitions, it reached a maximum at x=0.60 and x=0.80 respectively and then decreased.