A realization of excellent piezoelectricity and good thermal stability in CaBi2Nb2O9: Pseudo phase boundary

Abstract

AbstractPhase boundaries (PBs) are known to contribute to the outstanding performances of lead‐based and lead‐free materials. However, a lack of PBs restricts the promotion of piezoelectric performance in bismuth layer‐structured ferroelectrics (BLSFs). In this work, a pseudo PB, ie, pseudotetragonal distortion (regulated by Ce), is proposed to promote the piezoelectric properties of CaBi2Nb2O9‐based ceramics, and an excellent piezoelectric constant (d33) of 20.2 pC/N with a high Curie temperature of 923°C is obtained. Verified Ce incorporation into the (Bi2O2)2+ layer alters the environment of the (Bi2O2)2+ layer, thereby influencing the atomic displacement in the Nb‐O octahedron and modulating the theoretical spontaneous polarization (Ps). Strengthening of the pseudotetragonal distortion is favorable to the polarization switching, and maintains the theoretical Ps of ceramics at a high level, thus realizing the promotion of d33. Furthermore, pseudotetragonal distortion guarantees good thermal depoling performance of the ceramic, which remains at 89.6% (18.1 pC/N) of its initial d33 after depoling at 875°C. This work provides clear guidance on obtaining high d33 and good thermal stability in BLSFs.