Diffuse and relaxor phase transitions of Ba 0.95Bi 0.05Ti 1-xFe xO3 ceramics at x=0.00 to 1.00 of Fe content, prepared by solid state method

Abstract

The dielectric properties of iron and bismuth co-substituted BaTiO3 ceramic with the formula: Ba 0.95Bi 0.05Ti 1-xFe xO3 (BBTFx) for x=0.00 to 1.00, synthesis with solid state route, were characterized. The results of dielectric permittivity dependence of temperature show three dielectric 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). Calculating the relaxation parameters of ΔTrelax and the dispersion factor ΔƐ’r,max/ Ɛ’r,max, we have found that all the ceramics present a relaxation and a dispersion phenomenon. And the phase transition TO-T for x = 0.00 has the highest value of ΔTrelax while the dispersion factor has the highest value for the phase transition Tm at x = 0.60. The diffuseness parameter γ refined from Uchino law showed a diffuse phase transition for all the ceramics. While γ has a value close to 1 for TR-O at x = 0.00, which indicate a standard Curie-Weiss law. The dielectric evolution as function of frequency shows a resonance behavior for x=0.00 of Fe content while for the other ceramics we obtained a classical ferroelectric behavior.