Enhanced giant dielectric properties and improved nonlinear electrical response in acceptor-donor (Al3+, Ta5+)-substituted CaCu3Ti4O12 ceramics

• 作者: Jakkree BOONLAKHORN Narong CHANLEK Jedsada MANYAM Pornjuk SREPUSHARAWOOT Sriprajak KRONGSUK Prasit THONGBAI
• 来源期刊: 先进陶瓷（英文版）
• 年，卷（期）: 2021,（6）
• 所属期刊栏目: Research Article
• 页码范围: 1243-1255
• 页数: 13页
• 语种: 英文

摘要

The giant dielectric behavior of CaCu3Ti4O12 (CCTO) has been widely investigated owing to its potential applications in electronics; however, the loss tangent (tanδ) of this material is too large for many applications. A partial substitution of CCTO ceramics with either Al3+ or Ta5+ ions generally results in poorer nonlinear properties and an associated increase in tanδ (to～0.29–1.15). However, first-principles calculations showed that self-charge compensation occurs between these two dopant ions when co-doped into Ti4+ sites, which can improve the electrical properties of the grain boundary (GB). Surprisingly, in this study, a greatly enhanced breakdown electric field (～200–6588 V/cm) and nonlinear coefficient (～4.8–15.2) with a significantly reduced tanδ (～0.010-0.036) were obtained by simultaneous partial substitution of CCTO with acceptor–donor (Al3+, Ta5+) dopants to produce (Al3+, Ta5+)-CCTO ceramics. The reduced tanδ and improved nonlinear properties were attributed to the synergistic effects of the co-dopants in the doped CCTO structure. The significant reduction in the mean grain size of the (Al3+, Ta5+)-CCTO ceramics compared to pure CCTO was mainly because of the Ta5+ ions. Accordingly, the increased GB density due to the reduced grain size and the larger Schottky barrier height (Φb) at the GBs of the co-doped CCTO ceramics were the main reasons for the greatly increased GB resistance, improved nonlinear properties, and reduced tanδ values compared to pure and single-doped CCTO. In addition, high dielectric constant values (ε'≈ (0.52-2.7)× 104) were obtained. A fine-grained microstructure with highly insulating GBs was obtained by Ta5+ doping, while co-doping with Ta5+ and Al3+ resulted in a highΦb. The obtained results are expected to provide useful guidelines for developing new giant dielectric ceramics with excellent dielectric properties.