A New Strategy for Large Dynamic Piezoelectric Responses in Lead‐Free Ferroelectrics: The Relaxor/Morphotropic Phase Boundary Crossover

Abstract

One of the key problems in the existing lead-free piezoelectrics lies in how to further boost their dynamic piezoelectric responses, i.e., electrostrain and dynamic piezoelectric constants, in an effective and facile manner, making them comparable to those of widely used lead-based counterparts. In this work, a new strategy is developed to largely improve the dynamic piezoelectric properties of lead-free ferroelectrics using phase field simulations by combining the relaxor/ferroelectric crossover rendering potentially reversible electrostrain and the morphotropic phase boundary (MPB) providing easy paths of ferroelectric polarization rotations. Following the guidance of simulation results, Mn-doped (Bi 0.5 Na 0.5)TiO 3-BaTiO 3 lead-free piezoelectric ceramics with relaxor/MPB crossover are synthesized. A large reversible electrostrain (S max) of 0.55% with a promising piezoelectric constant d 33 * (S max /E max) of 917 pm V-1 at the designed relaxor/MPB crossover is obtained, outperforming almost all practical lead-free counterparts when taking both electrostrain and dynamic piezoelectric constants into consideration. The strategy of utilizing relaxor/MPB crossover provides a new route for enhancing the dynamic piezoelectric responses in lead-free ferroelectric perovskites.

Improved Energy Storage Properties Achieved in (K, Na)NbO3‑Based Relaxor Ferroelectric Ceramics via a Combinatorial Optimization Strategy

“…We can also observe that the polarization gradually becomes insensitive to temperature and the overall curve tends to be flat with increasing x , meaning the enhancement of relaxor behavior. [ 31 ] The reason is that the introduction of BZT reduces the T m of KNN ceramics and makes Stage 2 gradually move to near room temperature. Enlarged pictures of the microstructure of x = 0 and x = 0.15 systems at various temperatures are given in Figure 2c, d.…”

High‐Performance Strain of Lead‐Free Relaxor‐Ferroelectric Piezoceramics by the Morphotropic Phase Boundary Modification

“…[33][34][35] However, phase-field models for the characterization of electric-field-induced strains in BNT-based ceramics remain nascent. [36] Therefore, enabled by phase-field guidance and rational composition design, development of highperformance BNT-based ceramics is desirable for applications that feature actuators operating in a wide range of temperatures.…”

Optimization of Ferroelectric Ordering and Thermal Stability in Na1/2Bi1/2TiO3-Based Lead-Free Single Crystal through Defect Engineering

“…Ferroelectric domains, where the polar vectors aligned along the same direction spontaneously, were often utilized to evaluate the macroscopic ferroelectric and piezoelectric performance. − To further capture the dynamic information on ferroelectric domains, PFM was also performed in phase mode. In NBBT-Co, the polar nanodomains formed a pure stripe-like pattern, as shown in Figure a.…”