Synthesis, structural stability and phase diagram of BiFeO3–CaSnO3 ceramics

BiFeO3-based materials have received extensive attention in electronic device applications due to their high Curie temperature and large electromechanical response. In this study, new solid solutions of (1-x)BiFeO(3)xCaSnO(3) (BF-CS) ceramics were successfully synthesized via conventional solid-state reaction method. With increasing CS content, the ceramics exhibit a single-phase perovskite and the structure changes from a main rhombohedral phase with a small amount of impurity phase to a stable rhombohedral phase and then to MPB region separating the rhombohedral and orthorhombic phases in the composition of 0 = x = 0.15, indicating that introducing CS can stabilize the perovskite structure formed in the sintering process. Unfortunately, the solid solubility limit of CS into BF perovskite structure is reached when x > 0.15. The dielectric peak associated with oxygen vacancies become weaker and finally disappear at x = 0.15. Moreover, the ceramics with x = 0.12-0.15 feature saturated and square-shaped P-E hysteresis loops with increased polarization can be attributed to effectively promote domain switching process at MPB, in which the highest piezoelectric coefficient d33 = 259 pC/N can be ascribed to the combined effect of coexistence phases, high relative bulk density and low leakage current. In particular, a partial phase diagram is constructed in terms of temperature and composition, which helps to understand the structure-property relations. The distinct structures and phase transition behavior on each side of the vertical MPB line offer the guidelines and strategy to design other BF-based binary or ternary solid solutions with enhanced piezoelectric property in high temperature application.