Effects of La Concentration on the Structural and Dielectric Properties of 0.57BiFeO3-0.43PbTiO3 Crystalline Solutions

Crystalline solutions of 0.57(B_1-xLa_x)FeO₃-0.43PbTiO₃ (BLF-PT) for x=0, 0.1, 0.2 and 0.3 have been fabricated by traditional solid state reaction method. X-ray diffraction (XRD) analysis reveals that the tetragonal to rhombohedral phase transformation of BLF-PT occurs with the increase of La content. The dielectric and ferroelectric properties of BLF-PT were investigated at room temperature for different La contents. BLF-PT reveals strong ferroelectric characteristics for the lower La composition, which transfers to the relaxor ferroelectrics for x>0.2. The dielectric constant and remanent polarization achieve of 1461 and 33.5 muC/cm respectively for BLF-PT of x=0.2. The dielectric constant and polarization of BLF-PT are enhanced simultaneously with increasing La content. Our results demonstrate that BLF-PT are competitive piezoelectric ceramics.