Giant electromechanical strain response in lead‐free SrTiO3‐doped (Bi0.5Na0.5TiO3–BaTiO3)–LiNbO3 piezoelectric ceramics |
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Authors: | Lei Wu Bo Shen Querui Hu Jing Chen Yiping Wang Yidong Xia Jiang Yin Zhiguo Liu |
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Affiliation: | 1. National Laboratory of Solid State Microstructures, Nanjing University, Nanjing, China;2. College of Engineering and Applied Sciences, Nanjing University, Nanjing, China;3. Department of State Key Laboratory of Mechanics and Control of Mechanical Structures, Nanjing University of Aeronautics and Astronautics, Nanjing, China |
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Abstract: | Lead‐free 0.985(0.94?x)Bi0.5Na0.5TiO3–0.06BaTiO3–xSrTiO3]–0.015LiNbO3 (BNT–BT–xST)–LN, x=0‐0.05] piezoelectric ceramics were prepared using a conventional solid‐state reaction method. It was found that the long‐range ferroelectric order in the unmodified (BNT–BT)–LN ceramic was disrupted and transformed into the ergodic relaxor phase with the ST substitution, which was well demonstrated by the dramatic decrease in remnant polarization (Pr), coercive field (Ec), negative strain (Sneg) and piezoelectric coefficient (d33). However, the degradation of the ferroelectric and piezoelectric properties was accompanied by a significant increase in the usable strain response. The critical composition (BNT–BT–0.03ST)–LN exhibited a maximum unipolar strain of ~0.44% and corresponding normalized strain, Smax/Emax of ~880 pm/V under a moderate field of 50 kV/cm at room temperature. This giant strain was associated with the coexistence of the ferroelectric and ergodic relaxor phases, which should be mainly attributed to the reversible electric‐field‐induced transition between the ergodic relaxor and ferroelectric phases. Furthermore, the large field‐induced strain showed relatively good temperature stability; the Smax/Emax was as high as ~490 pm/V even at 120°C. These findings indicated that the (BNT–BT–xST)–LN system would be a suitable environmental‐friendly candidate for actuator applications. |
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Keywords: | ferroelectricity/ferroelectric materials lead‐free ceramics phase transformations relaxors strain |
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