Enhanced ferroelectric and piezoelectric properties of BiFeO3-BaTiO3 lead-free ceramics by simultaneous optimization of Bi compensation and sintering conditions

Lead-free piezoelectric ceramics 0.7Bi(1+x)FeO(3)-0.3BaTiO(3) (B1+xF-BT, 0 <= x <= 0.04) with excellent piezoelectric performance were synthesized with conventional sintering methods. The impacts of Bi compensation and sintering conditions on the structure and electrical properties of the piezoelectric ceramics were studied. The results showed that the samples (x <= 0.02) exhibited pure perovskite structures, and a Bi25FeO40 impurity phase appeared in the samples (x >= 0.03). Appropriate compensation with Bi had an important effect on microstructures and electrical properties. Optimal piezoelectric and ferroelectric properties and the highest relative density were achieved with the x = 0.02 sample. In addition, various dwell times (t(s)) were used during quenching for the sample with x = 0.02. Excellent piezoelectric and ferroelectric properties (d(33) = 192 pC/N, P-r = 41.71 mu C/cm(2), T-c = 493 degrees C) were achieved with the sample at t(s) = 3 hQ, which was ascribed to the decreased concentration of oxygen vacancies and enhanced lattice distortion. The present research on simultaneous optimization of Bi compensation and sintering conditions will provide guidelines for designing BF-BT ceramics used in several device applications.