Lanthanum‐Induced Morphotropic Phase Boundary in BiFeO₃–BaTiO₃‐Based Lead‐Free Piezoelectric Ceramics

Abstract

La x Fe 0.98 Ga 0.02 O 3 -0.29BaTiO 3 þ 0.1wt%MnO 2 ceramics are fabricated via a traditional solid-state reaction route. Rietveld refinement analysis of X-ray diffraction data shows that all the studied ceramics consist of rhombohedral and tetragonal phases. The La-free samples are dominated by rhombohedral phase, the proportion of which, however, gradually decreases with the addition of La. And in 0.005 ≤ x ≤ 0.02, the ceramics have approximately equal proportions of rhombohedral and tetragonal phases, showing the characteristics of typical morphotropic phase boundary (MPB). The optimal piezoelectric properties (d 33 ¼ 178 pC N À1 and k p ¼ 0.31) are achieved at x ¼ 0.005, owing to the MPB. A more apparent relaxor behavior is found to be induced with the addition of La. Furthermore, the ceramics also exhibit good insulation properties and hightemperature stability of piezoelectric properties, which is very important for practical uses, especially for those in high-temperature environments.

Modifying electric and multiferroic properties of lead-free 0.7BFO-0.3BTO ceramics via Sm and Ga co-doping

“…The increase at x = 0.15 is due to nearly equal proportions of R and T phases, appears at this concentration as it has more spontaneous polarization vectors from both the phases which disturbs after further increment of Sm concentration as in the case of La modified BFO-BTO ceramics [43]. Specifically, it is observed that high T C of 550 °C is achieved for x  0.025 of the composite ceramics.…”