Enhanced piezoelectric performance of lead-based ceramics via multi-B site ion design and local structural disorder

Abstract

The high-entropy concept has emerged as a promising strategy for designing ferroelectric ceramics with superior piezoelectric properties. To clarify the role of equal-valence B-site cations within this framework, we synthesized a series of PNN-PMeN-PT (Me = Sc, In, Lu) ceramics. When Sc³⁺, In³⁺, and Lu³⁺ were introduced in equimolar proportions, the piezoelectric coefficient (d₃₃) increased from 938 pC N⁻¹ to 1012 pC N⁻¹, aligning with high-entropy predictions. However, the maximum d₃₃ value of 1046 pC N⁻¹ was achieved by deviating from this ratio, specifically with a higher fraction of smaller Sc³⁺ and a lower fraction of larger Lu³⁺. Analyses based on both Landau theory and fluctuating local polarization theory reveal that this asymmetric ionic ratio further enhances the distortion of piezoelectric functional cells, leading to optimal performance. Electrical characterization and piezoresponse force microscopy confirm that the outstanding properties originate from a synergistic design: a globally disordered matrix established via multi-cation doping, augmented by local structural heterogeneity tuned through the Sc³⁺/Lu³⁺ ratio. Our findings highlight that advancing ultrahigh piezoelectricity systems requires deliberate engineering of local piezoelectric functional cells.