Investigation of (1−x)(Bi0.94La0.06)(Ga0.05Fe0.95)O3-xPbTiO3 ceramics for high temperature applications

BiFeO3-PbTiO3 binary system doped with small amount of La3+ and Ga3+ was investigated for the development of piezoelectric ceramics with high Curie temperatures. Crystalline solutions of (1−x)(Bi0.94La0.06)(Ga0.05Fe0.95)O3-xPbTiO3 (BLGF-xPT) for x=0.35, 0.37, 0.4 and 0.45 have been fabricated by the solid-state reaction method. X-ray diffraction reveals that BLGF-PT has a single perovskite structure with a mixed phase region at x=0.35-0.37. The dielectric constant (K), loss tangent (tan δ), Curie temperature (TC), remnant polarization (Pr) and piezoelectric constant (d33) of 700, 0.021, 532 °C, 30 μC/cm2 and 63 pC/N respectively, have been achieved for x=0.35. The strain under the electric field of 90 kV/cm was measured to be 0.107% for x=0.37 and the planar electro-mechanical coupling coefficient (Kp) of 19% was stable under 310 °C, about 60% of its TC, indicating high thermal stability of the piezoelectric properties.