Realizing super-high piezoelectricity and excellent fatigue resistance in domain-engineered bismuth titanate ferroelectrics Shaoxiong Xie $ ^{a,b,*} $ , Qian Xu $ ^{c,1} $ , Qiang Chen $ ^{b} $ , Jianguo Zhu $ ^{d} $ , Qingyuan Wang $ ^{a,*} $ $ ^{a} $ Institute for Advanced Study, Chengdu University, Chengdu 610106, China $ ^{b} $ Department of Mechanical Engineering, Kyushu University, Fukuoka 819-0395, Japan $ ^{c} $ School of Architecture and Civil Engineering, Xihua University, Chengdu 610039, China $ ^{d} $ College of Materials Science and Engineering, Sichuan University, Chengdu 610065, China Bismuth titanate (BIT) is widely known as one of the most prospective lead-free ferroelectric and piezoelectric materials in advanced high-temperature sensing applications. Despite significant advances in developing BIT ferroelectrics, it still faces major scientific and engineering challenges in realizing super-high performance to meet next-generation high-sensitivity and light-weight applications. Here, we conceived a novel ferroelectric domain-engineered BIT ceramic system that exhibits super-high piezoelectric performance (d₃₃ ~ 38.5 pC/N, d₃₃* ~ 46.7 pm/V at low electric field) and excellent fatigue resistance (stable up to 10⁷ cycles). Our results reveal that the introduction of high-density layered (001)-type 180° domain walls with flexible polarization rotation features and the formation of small-size multi-domain states with low energy barriers are mainly responsible for the excellent electrical performance. To our best knowledge, it is the first time to reveal such intriguing domain structures in BIT ceramics in detail, especially from the atomic-scale perspective by using Z-contrast imaging in combination with atomic-resolution polarization mapping. We believe that this breakthrough conduces to comprehensively understand structural features of ferroelectric domains in BIT ceramics, and also opens a window for future developments of super-high performance in bismuth layer-structured ferroelectrics via domain engineering. Keywords: Bismuth titanate; Electrical performance; Lattice distortion; Domain structures; Atomic-resolution polarization mapping ### 1. Introduction Piezoelectric materials, which can directly interconvert mechanical energy and electrical energy, have been widely applied in various fields ranging from consumer electronics to high-end industries. With the rapid development of aerospace, geological exploration, and nuclear power generation, there has been a dramatic increase in the demand for high-temperature piezoelectric materials that can be operatedRealizing super-high piezoelectricity and excellent fatigue resistance in domain-engineered bismuth titanate ferroelectrics Shaoxiong Xie $ ^{a,b,*} $ , Qian Xu $ ^{c,1} $ , Qiang Chen $ ^{b} $ , Jianguo Zhu $ ^{d} $ , Qingyuan Wang $ ^{a,*} $ $ ^{a} $ Institute for Advanced Study, Chengdu University, Chengdu 610106, China $ ^{b} $ Department of Mechanical Engineering, Kyushu University, Fukuoka 819-0395, Japan $ ^{c} $ School of Architecture and Civil Engineering, Xihua University, Chengdu 610039, China $ ^{d} $ College of Materials Science and Engineering, Sichuan University, Chengdu 610065, China Bismuth titanate (BIT) is widely known as one of the most prospective lead-free ferroelectric and piezoelectric materials in advanced high-temperature sensing applications. Despite significant advances in developing BIT ferroelectrics, it still faces major scientific and engineering challenges in realizing super-high performance to meet next-generation high-sensitivity and light-weight applications. Here, we conceived a novel ferroelectric domain-engineered BIT ceramic system that exhibits super-high piezoelectric performance (d₃₃ ~ 38.5 pC/N, d₃₃* ~ 46.7 pm/V at low electric field) and excellent fatigue resistance (stable up to 10⁷ cycles). Our results reveal that the introduction of high-density layered (001)-type 180° domain walls with flexible polarization rotation features and the formation of small-size multi-domain states with low energy barriers are mainly responsible for the excellent electrical performance. To our best knowledge, it is the first time to reveal such intriguing domain structures in BIT ceramics in detail, especially from the atomic-scale perspective by using Z-contrast imaging in combination with atomic-resolution polarization mapping. We believe that this breakthrough conduces to comprehensively understand structural features of ferroelectric domains in BIT ceramics, and also opens a window for future developments of super-high performance in bismuth layer-structured ferroelectrics via domain engineering. Keywords: Bismuth titanate; Electrical performance; Lattice distortion; Domain structures; Atomic-resolution polarization mapping ### 1. Introduction Piezoelectric materials, which can directly interconvert mechanical energy and electrical energy, have been widely applied in various fields ranging from consumer electronics to high-end industries. With the rapid development of aerospace, geological exploration, and nuclear power generation, there has been a dramatic increase in the demand for high-temperature piezoelectric materials that can be operated