Effects of la concentration on the structural and dielectric properties of 0.57BiFeO3-0.43PbTiO3 crystalline solutions

Crystalline solutions of 0.57(Bi_1-infinLa_infin)FeO₃-0.43PbTiO₃ (BLF-PT) for x = 0, 0.1, 0.2, and 0.3 were fabricated by the traditional solid state reaction method. X-ray diffraction analysis revealed that the tetragonal-to-rhombohedral phase transformation of BLF-PT occurred with an increase of the La content. The dielectric and ferroelectric properties of BLF-PT were investigated at room temperature for different La contents. BLF-PT revealed strong ferroelectric characteristics for the lower La composition, and transferred to relaxor ferroelectrics for x > 0.2. The dielectric constant and remanent polarization were 1461 and 33.5 muC/cm², respectively, for BLF-PT of x = 0.2. The dielectric constant and polarization of BLF-PT were enhanced simultaneously with increasing La content. Our results demonstrate that BLF-PT is a competitive piezoelectric ceramic.