Improved dielectric and ferroelectric properties of high Curie temperature (1-x)BiFeO3-xPbTiO3 ceramics by aliovalent ionic substitution

Ceramics of 0.67Bi(Fe1-xTix)O3+x/2-0.33PbTiO(3) (x=0, 0.005, 0.01, 0.02, 0.04) were prepared by solid state reactions, with a relative density of 94%-97%. The dielectric and ferroelectric properties of the ceramics have been significantly improved by means of aliovalent ionic substitution of Ti4+ for Fe3+, which reduces the electric conductivity. The temperature variation of the dielectric constant has been measured up to the Curie temperature as high as T-C=650 degrees C. A saturated dielectric hysteresis loop with a remnant polarization (P-r) of 9 mu C/cm(2) is displayed in the 0.5 mol % Ti4+-substituted sample at room temperature. P-r reaches 17 mu C/cm(2) in the sample with 2 mol % Ti4+ even though the hysteresis loop is not saturated, suggesting that a much higher saturated polarization can be expected in the Ti4+-substituted BiFeO3-PbTiO3 ceramics. (c) 2006 American Institute of Physics.