Enhanced Electromechanical Performance in Lead-free (Na,K)NbO₃-Based Piezoceramics via the Synergistic Design of Texture Engineering and Sm-Modification

Abstract

Next-generation electromechanical conversion devices have a significant demand for high-performance lead-free piezoelectric materials to meet environmentally friendly requirements. However, the low electromechanical properties of lead-free piezoceramics limit their application in high-end transducer applications. In this work, a 0.96K 0.48 Na 0.52 Nb 0.96 Sb 0.04 O 3 -0.04(Bi 0.5−x Sm x )Na 0.5 ZrO 3 (abbreviated as T-NKN-xSm) ceramic was designed through phase regulation and texture engineering, which is expected to solve this difficulty. Through our research, we successfully demonstrated the enhanced electromechanical performance of lead-free textured ceramics with a highly oriented [001] c orientation. Notably, the T-NKN-xSm textured ceramics doped with 0.05 mol % Sm exhibited the optimal electromechanical performance: piezoelectric coefficient d 33 ≈ 710 pC N -1 , longitudinal electromechanical coupling k 33 ≈ 0.88, planar electromechanical coupling k p ≈ 0.80, and Curie temperature T c ≈ 244 °C. Finally, we conducted a detailed investigation into the phase and domain structures of the T-NKN-Sm ceramics, providing valuable insights for achieving high electromechanical properties in NKN-based ceramics. This research serves as a crucial reference for the development of advanced electromechanical devices by facilitating the utilization of lead-free piezoelectric materials with superior performance and environmental benefits.

Composite Scheme for Deferred Thermal Depolarization of Lead-Free Bi0.5Na0.5TiO3-Based Piezoelectric Ceramics

“…Based on this PFM data, the 3D autocorrelation images were obtained, as displayed in Figure a2,b2. The ferroelectric ordering and mean size of the domain structure were quantitatively characterized by the average autocorrelation function − ⟨ C ( r ) ⟩ = σ 2 exp [ − ( r / false⟨ ξ false⟩ ) 2 h ] where σ is a constant, and r and h represent the distance from the central peak and the roughness of the polarization interface, respectively. ⟨ξ⟩ is the short-range correlation length of the domain structure and thus, 2⟨ξ⟩ can represent the average domain size.…”

“…Larger domain sizes and enhanced ferroelectric ordering usually favor delayed thermal depolarization behavior . Note that there is a strong dependence between the domain and phase structure. ,− For example, complex domains of about 100 nm were observed in the BNT–4BT ceramics with the R phase, while the BNT–6BT (MPB) ceramics consisted mainly of nanometer-sized domains. , Meanwhile, the domain pattern of BNT-based materials is also affected by the stresses. For the BNT–7BT substrate using the aerosol deposition of an electrode, the deposition-induced residual stresses result in long-range ferroelectric domain ordering .…”