Relationship between chemical composition, phase structure and piezoelectric property of BiFeO3–BaTiO3 ceramics near morphotropic phase boundary

The chemical composition and phase structure of (1−x)BiFeO3−xBaTiO3 (BF–xBT) ceramics near morphotropic phase boundary (MPB) are controversial so far. Particularly, no report mentioned BT content dependence of phase ratio of BF–xBT ceramics near MPB. Herein, BF–xBT (x = 0.24–0.38) ceramics with pure perovskite structure and dense microstructure were prepared by conventional sintering technics. The phase composition, electric resistivity, dielectric, ferroelectric and piezoelectric properties of the ceramics were systematically investigated. The results showed that the phase structure of the ceramics transforms from rhombohedral (R) to pseudocubic (pC) with increasing BT content, and the MPB with R-pC phase coexistence was determined in the range of 0.28 ≤ x ≤ 0.33. In addition, as BT content increases for the ceramics near MPB, the phase fraction of R decreases gradually from 75.3% for BF–0.28BT to 36.9% for BF–0.33BT. Especially for BF–0.31BT ceramics, the phase fraction of R (49.1%) and pC (50.9%) are almost equal to each other. Enhanced piezoelectricity and ferroelecricity were attained in the ceramics near MPB. Owing to more proper R/pC phase ratio and strong ferroelectricity, the best piezoelectric coefficient d33 = 190 pC/N was achieved in BF–0.31BT ceramics. This work revealed the relationship between chemical composition, phase structure and piezoelectric property of BF–BT piezoceramics near MPB, which is helpful to further improve the piezoelectric property of BF–BT via optimizing phase structure and/or composition engineering.