Low-temperature dielectric relaxation associated with NbO_6 octahedron distortion in antimony modified potassium sodium niobate ceramics  

作　　者：Nan Zhang Xiang Lv Xi-xiang Zhang Jing Lyu Shuo-Wang Yang Jiagang Wu 

机构地区：[1]Department of Materials Science,Sichuan University,Chengdu 610065,China [2]Division of Physical Science and Engineering,King Abdullah University of Science and Technology,Thuwal 23955-6900,Saudi Arabia [3]Department of Chemistry,National University of Singapore,3 Science Drive 3,117543,Singapore [4]Institute of High Performance Computing,Agency for Science,Technology and Research,1 Fusionopolis Way,#16-16 Connexis,138632,Singapore

出　　处：《Journal of Materials Science & Technology》2022年第20期189-198,共10页材料科学技术（英文版）

基　　金：the National Natural Science Foundation of China(Nos.52061130216 and 52002252);the Sichuan Science and Technology Program(No.2020YJ0070);the Central Funds Guiding the Local Science and Technology Development of Sichuan Province(2021ZYD0022);the Fundamental Research Funds for the Central Universities(YJ2021154);the R&D Projects in Key Fields of Guangdong Province,China(No.2020B0109380001);the support from King Abdullah University of Science and Technology(KAUST)。

摘　　要：Although the antimony(Sb) has been widely used to modify potassium sodium niobate(KNN) ceramics for tailoring the phase structure and performance, the role of Sb still remains insufficiently understood,consequently hindering the understanding of the physical origin of high-performance KNN-based ceramics. Here, we combine the experiments and first-principles calculations to deeply reveal the effects of Sb on KNN ceramics. Our results reveal a re-entrant-like relaxation behavior near the rhombohedralorthorhombic(R-O) phase transition at the low content of Sb, which transforms into a canonical one at higher content of Sb. First-principles calculations show a significantly decreased difference in the bond length of six B-O bonds of Nb O6 octahedral in Sb-modified KNN ceramics compared to pristine KNN ceramics, responsible for the low-temperature re-entrant-like dielectric relaxation. Furthermore, the addition of Sb would soften the B-O repulsion and gradually break the long-range ferroelectric ordering,resulting in the occurrence of nanoscale domains and enhanced local heterogeneity. Finally, we find that the optimized piezoelectric properties are the trade-off between the long-range ferroelectric ordering and the local heterogeneity. Therefore, this work not only deeply reveals the effects of Sb on KNN ceramics from multi-scale perspectives but also helps the future composition design for achieving high piezoelectricity.

关 键 词：KNN-based ceramics Re-entrant-like relaxation COVALENCY Multiphase coexistence Local heterogeneity 

分 类 号：TQ174.7[化学工程—陶瓷工业]