Effects of La substituent on ferroelectric rhombohedral/tetragonal morphotropic phase boundary in (1−x)(Bi,La)(Ga0.05Fe0.95)O3–xPbTiO3 piezoelectric ceramics

Crystalline solutions of (1−x)(Bi,La)(Fe0.95Ga0.05)O3–xPbTiO3 (BLGF–PT) have been fabricated with La concentrations of 0, 10, and 20 at. %. The BLGF–PT system has been found to have excellent insulation resistivity ⩽1013 Ω cm. In addition, La substituent was found to decrease the coercive field, resulting in much improved dielectric and piezoelectric properties. A shift in the morphotropic phase boundary of BLGF–PT with increasing La content was identified for x=0.3, 0.4, and 0.43. We have achieved optimized dielectric constant, loss factor, Curie temperature, remnant polarization, and piezoelectric d33 properties of 881, 0.037, 386 °C, 30 μC/cm2 and 163 pC/N, respectively, for 0.6BLGF–0.4PT with 10 at. % La. These results clearly demonstrate that BLGF–PT is a competitive alternative piezoelectric material to Pb(Zr,Ti)O3 with reduced lead content.