The ultrahigh piezoelectric coefficient (d 33 ≥ 1000 pC/N) exhibited by piezoelectric Pb(Zr,Ti)O 3 (PZT) ceramics not only captivates researchers but also holds considerable practical value across various applications. While significant progress has been made in enhancing piezoelectricity of PZT-based ceramics, novel mechanisms need to be proposed to explain the piezoelectric behavior of new systems with ultrahigh d 33 . In this study, we initially employ LiNbO 3 as an additive to enhance the piezoelectric properties of the Pb(Ni 1 / 3 Nb 2 / 3 )O 3 –PbZrO 3 –PbTiO 3 ceramics. and the optimal performance is achieved by incorporating 1.5 mol% of LiNbO 3 into the system, resulting in an ultrahigh d 33 ∼1178 pC/N ( d 33 * ∼1560 p.m./V (@ E = 5 kV/cm)). The corresponding mechanism for this superior piezoelectric response involves the AB-site co-doping effect, especially the ( Li Pb ′ − Nb Zr / Ti ∙ ) defect dipoles formed by the introduction of LiNbO 3 . In particular, the addition of LiNbO 3 leads to a more uniform distribution of domain sizes, thereby further enhancing the ultrahigh piezoelectricity. These findings pave the way for a deeper under-standing of the origin of ultrahigh piezoelectric properties and make substantial contributions to the advancement of piezoelectric materials for practical applications in electromechanical devices.
La 1- x Sr x Co 0.9 Fe 0.1 O 3 ( x = 0, 0.1, 0.15, 0.2) perovskite oxides were successfully synthesized by the sol–gel method, with Sr 2 ⁺ doping at the A-site and Fe 3+ at B-site of LaCoO 3 . The effect of AB-site co-doping on the structure, morphology, electromagnetic parameters, and microwave absorption properties was systematically investigated. The optimal composition La 0.85 Sr 0.15 Co 0.9 Fe 0.1 O 3 achieved a minimum reflection loss of −42.79 dB at 1.5 mm thickness and an effective absorption bandwidth of 5.44 GHz (11.92–17.36 GHz) at 1.8 mm. This remarkable performance arises not only from the presence of defects and the enhanced polarization loss due to oxygen vacancies induced by Sr 2+ and Fe 3+ co-doping, but also from synergistic effects including multiple reflections and scattering from the porous microstructure, interfacial polarization, and magnetic loss mechanisms. These results demonstrate that simultaneous A-site and B-site doping is an effective strategy to achieve thin, broadband, and high-performance microwave absorbers, highlighting a promising route for the development of perovskite-based EM wave absorption materials.
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