Ultra-high piezoelectric properties of BiFeO3-BaTiO3 lead-free piezoelectric ceramics enabled by a one-step sintering process (IMAGE)
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(a) Schematic illustration of the formation of internal bias fields in BF‑BT ceramics. Defect dipoles (e.g., FeFe' -VO•• and VBi''' -VO•• ) and space charges at grain boundaries generate built‑in electric fields that modulate the ferroelectric switching and strain behavior.(b) Effect of internal bias fields on unipolar strain before and after poling. (c) Comparison between conventional multi‑step solid‑state sintering and the novel one‑step sintering method. The conventional process suffers from the thermodynamically unstable temperature window of BiFeO3, leading to secondary phases, Bi evaporation, and high leakage. In contrast, the one‑step method directly uses BaTiO3 as a starting material and integrates binder removal, pre‑sintering, and sintering into a single heat treatment, effectively bypassing the unstable window and suppressing defects.(d) Performance comparison of the obtained 0.7BiFeO3‑0.3BaTiO3 ceramic with other representative lead‑free piezoelectric systems (KNN‑based and BNT‑based) and previously reported BF‑BT ceramics. The material simultaneously achieves a high piezoelectric coefficient d33= 201 pC/N, a large high‑field coefficient d33* = 1021 pm/V, a high Curie temperature TC = 501 °C, and a large strain of 0.38%, demonstrating outstanding comprehensive performance for high‑temperature actuator applications.
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Journal of Advanced Ceramics, Tsinghua University Press
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