Effectively improved piezoelectricity in high-temperature Arrhenius CBT ceramics by modifying potential energy profile and spontaneous polarization

Enhancing the piezoelectricity of CaBi₄Ti₄O₁₅ (CBT) ceramics is crucial for improving their application potential in high-temperature piezoelectric devices. Here, we propose a strategy involving the introduction of larger Na/Bi ions at the A-site, effectively inhibiting the tilt of oxygen octahedra and flattening the potential energy profile. This flattening enhances the variation in polarization under external fields. Concurrently, substituting Nb/Mn at the B-site increases the deviation between positive and negative ionic centers, leading to stronger spontaneous polarization, while the induced defect dipoles restrict oxygen vacancy migration and increase the direct current resistivity (ρ_dc). The flattened potential energy profile and increased spontaneous polarization significantly enhance the overall performance of CBT ceramics, with the piezoelectric constant (d₃₃) reaching 25 pC/N when the Curie temperature (T_C) = 752 °C. Piezoresponse force microscopy (PFM) and transmission electron microscopy (TEM) revealed submicron-long rectangular domains and nanoscale domains in the modified composition, indicating a high density of domain walls. This study presents an effective approach for enhancing the piezoelectric properties of bismuth layered-structured ferroelectrics (BLSFs), thereby improving the application potential of BLSFs at high temperatures.