The lead-free piezoceramics of K0.5Na0.5Nb0.996Cu0.01O3-xFx (KNCNF-x) were synthesized via a conventional solid sintering process, and the inhibition effects of F-O substitution on the defect structures of oxygen vacancies and defect complexes were investigated. The KNCNF-0 ceramic without F doping has the highest level of oxygen vacancies and defect complexes. However, as the level of F increases, the contents of oxygen vacancies and defect complexes decrease correspondingly, and thus, the evolution of hardening to softening behaviors in the ceramics is observed. As a result, the KNCNF-0 piezoceramic shows extremely hardened electrical behaviors (a completely constricted P-E hysteresis loop, large Ei of 10.7 kV cm-1, kp of 38%, d33 of 83 pC N-1, Qm of 3110, and tan δ of 0.2%), while the ceramic with x = 0.28 exhibits softened ferroelectric and piezoelectric characteristics (a non-shrinking P-E hysteresis loop, declining Ei of 7.5 kV cm-1, enhanced kp of 42%, optimized d33 of 103 pC N-1, reduced Qm of 1031, and increased tan δ of 0.6%). This study provides new insights into the modulation of defects and electrical performance of KNN ceramics.

中文翻译：

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氟-氧取代对铜掺杂KNN陶瓷的缺陷和电学行为的调节。

通过传统的固体烧结法合成了K0.5Na0.5Nb0.996Cu0.01O3-xFx（KNCNF-x）的无铅压电陶瓷，并研究了FO取代对氧空位和缺陷配合物缺陷结构的抑制作用。 。没有F掺杂的KNCNF-0陶瓷具有最高水平的氧空位和缺陷配合物。然而，随着F含量的增加，氧空位和缺陷配合物的含量相应地降低，因此，观察到陶瓷中从硬化到软化行为的演变。结果，KNCNF-0压电陶瓷表现出极强的电性能（完全收缩的PE磁滞回线，大Ei为10.7 kV cm-1，kp为38％，d33为83 pC N-1，Qm为3110和棕褐色δ为0.2％），而x = 0的陶瓷。28呈现出软化的铁电和压电特性（不收缩的PE磁滞回线，Ei下降7.5 kV cm-1，kp增强42％，d33优化为103 pC N-1，Qm降低1031，tanδ增加0.6％）。这项研究为KNN陶瓷的缺陷调制和电性能提供了新的见解。