There is an urgent need for piezoelectric materials possessing both high piezoelectric properties and good thermal stability to facilitate the advancement of high temperature piezoelectric devices. However, conventional strategy for enhancing piezoelectricity via chemical modifications often comes at the cost of thermal stability due to a drop in Curie temperatures. In this study, we achieved remarkable results in <001>-oriented 0.75BiFeO₃–0.25BaTiO₃ (0.75BF–0.25BT) lead-free textured ceramics. These textured ceramics exhibit a high Curie temperatures T_C of 552 ℃, large piezoelectric coefficients d₃₃ of 265 pC/N, and exceptional piezoelectric thermal stability, with minimal variation of 8% across temperature from 25 ℃ to 300 ℃. Compared to randomly oriented ceramics, the piezoelectric coefficient is about 2.5 times higher, marking it as one of the highest reported value for ceramics with T_c near 550 ℃. The enhanced piezoelectric properties can be ascribed to improvements in both intrinsic lattice distortions and extrinsic non-180° domain motions, while the excellent piezoelectric thermal stability is attributed to the stable domain texture. These superior properties of the studied textured 0.75BF–0.25BT ceramics position them as competitive lead-free candidates for high-temperature piezoelectric applications.

The 0.93(Na_0.5Bi_0.5)_1-xSm_xTiO₃-0.07BaTiO₃ multifunctional ceramics were prepared by solid-phase reaction method. The phase structure, microstructure, electrical and photoluminescent properties were systematically studied. With increasing x, the ceramics undergoes the phase transition from rhombohedral to tetragonal with some rhombohedral distortion, along with a reduced grain size and increased relative density. On the other hand, the Sm³⁺ doping enhances the electric-field driven reversible phase transition and domain size, and reduces the domain walls, thereby contributing to improved piezoelectricity and decreased depolarization temperature (T_d) from 91 ℃ to 40 ℃. Excellent piezoelectric properties of d₃₃ = 213 pC/N and k_p = 29.9% are achieved in the x = 0.010 ceramic. Under excitation (407 nm), the Sm³⁺-doped ceramic exhibits bright reddish-orange fluorescence at 564, 599, 646 nm and 710 nm. A polarization-induced enhancement of photoluminescence is obtained in BNBT-xSm ceramics with an improved relative intensity of emission band at 646 nm. These results indicate that Sm³⁺-doped BNBT ceramics show great potential in electro-optic integration and coupling device applications.