Modulation of defects and electrical behaviors of Cu-doped KNN ceramics by fluorine–oxygen substitution. Issue 4 (8th January 2020)

• Record Type: Journal Article
• Authors: Liao, You; Wang, Dongmei; Wang, Hua; Zhou, Lingxi; Zheng, Qiaoji; Lin, Dunmin
• Is Part Of: Dalton transactions. Volume 49:Issue 4(2019)
• Page Start: 1311
• Page End: 1318
• Publication Date: 2020-01-08
• Subjects: Chemistry, Inorganic -- Periodicals; Chemistry, Physical and theoretical -- Periodicals; Chemistry, Inorganic -- Periodicals; 546.05
• DOI: 10.1039/c9dt04133h
• Languages: English
• ISSNs: 1477-9226

Abstract

Abstract : F–O substitution in Cu-doped KNN ceramics decreases oxygen vacancies and defect complexes, leading to the hardening-softening evolution of electrical behaviors. Abstract : The lead-free piezoceramics of K0.5 Na0.5 Nb0.996 Cu0.01 O3− x F x (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 E i of 10.7 kV cm −1, k p of 38%, d 33 of 83 pC N −1, Q m 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 E i of 7.5 kV cm −1, enhanced k p of 42%, optimized d 33 of 103 pC N −1, reduced Q m 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.