Structural, dielectric and ferroelectric properties of Bi(Fe1-xTix)O3+x/2-PbTiO3 ceramics with MPB compositions

Dense ceramics of 0.67Bi(Fe
_1-x
Ti
_x
)O
_3+x/2
-0.33PbTiO
₃
(x=0, 0.005, 0.01, 0.02, 0.04) with MPB compositions have been synthesized by solid state reactions. Structural characterization by X-ray diffraction (XRD) reveals the simultaneous presence of a tetragonal, an orthorhombic, and a rhombohedral phases in 0.67BiFeO
₃
-0.33PbTiO
₃
. The electric conductivity decreases with the increasing Ti
⁴⁺
substitution amount. As a result, the temperature dependence of dielectric constant of the Ti
⁴⁺
-doped ceramics were measured up to their ferroelectric Curie point (T
_C
) as high as 650degC, and the saturated dielectric hysteresis loop with remnant polarization of 9 muC/cm
²
was obtained in 0.5 mol% Ti
⁴⁺
-doped ceramic. A Pr of 17 muC/cm
²
was displayed in unsaturated P-E loop of 2 mol% Ti
⁴⁺
-doped sample, which indicates that a much higher saturated polarization can be expected on the Ti
⁴⁺
-substituted BiFeO
₃
-PbTiO
₃
ceramics.