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It is well-known that the performance of BiFeO3BaTiO3(BF-BT) ceramics is sensitive to composition, calcining and sintering temperature (Tcaland Tsint) due to the formation of Bi25FeO39and/or Bi2Fe4O9impurities and/or the volatilization of Bi2O3. We report remarkably stable electrical properties over the range of −0.03 ≤ x ≤ 0.05 and 930 °C ≤ Tsint≤ 970 °C in 0.7Bi(1+x)FeO3-0.3BaTiO3ceramics prepared by one-step process. This method avoids the thermodynamically unstable region of BiFeO3and prevents the formation of Bi25FeO39and/or Bi2Fe4O9impurities even when the addition of α-Bi2O3raw material is intentionally deficient or rich to make off-stoichiometric BF-BT, thus greatly improving the robustness of compositional and processing. Rhombohedral-pseudocubic phase coexists in all ceramics, and their CR/CPCfraction are 48.0/52.0–50.6/49.4 and 55.9/44.1–56.6/43.4 when xincreases from −0.05 ≤ x ≤ 0 to 0.01 ≤ x ≤ 0.05. The stable electrical properties of d33 = 180–205 pC/N, Pr = 17.9–23.8 μC/cm2, and TC = 485–518 °C are achieved. The maximum d33T/d33RTof BF-BT is twice that of soft PZT, superior to most the-state-of-art lead-free ceramics. Our results provide a synthesis strategy for designing high performance piezoelectric materials with good stability and easy industrialization.

NaNbO3-based ceramics usually show ferroelectric-like P-Eloops at room temperature due to the irreversible transformation of the antiferroelectric orthorhombic phase to ferroelectric orthorhombic phase, which is not conducive to energy storage applications. Our previous work found that incorporating CaHfO3into NaNbO3can stabilize its antiferroelectric phase by reducing the tolerance factor (t), as indicated by the appearance of characteristic double P-Eloops. Furthermore, a small amount of MnO2addition effectively regulate the phase structure and tolerance factor of 0.94NaNbO3-0.06CaHfO3(0.94NN-0.06CH), which can further improve the stability of antiferroelectricity. The XRD and XPS results reveal that the Mn ions preferentially replace A-sites and then B-sites as increasing MnO2. The antiferroelectric orthorhombic phase first increases and then decreases, while the tshows the reversed trend, thus an enhanced antiferroelectricity and the energy storage density Wrecof 1.69 J/cm3at 240 kV/cm are obtained for 0.94NN-0.06CH-0.5%MnO2(in mass fraction). With the increase of Mn content to 1.0 % from 0.5 %, the efficiency increases to 81 % from 45 %, although the energy storage density decreases to 1.31 J/cm3due to both increased tolerance factor and non-polar phase.