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이상섭,이창헌,즈엉 짱 안,웬 호앙 티엔 코이,한형수,이재신,Lee, Sang Sub,Lee, Chang-Heon,Duong, Trang An,Nguyen, Hoang Thien Khoi,Han, Hyoung-Su,Lee, Jae-Shin 한국전기전자재료학회 2021 전기전자재료학회논문지 Vol.34 No.1
This study investigated the structural, dielectric, ferroelectric, and strain properties of (0.98-x)Bi1/2Na1/2TiO3-0.02BiFeO3-xSrTiO3 (BNT-BF-100xST, x=0.20, 0.22, 0.24, 0.26, and 0.28). All samples were successfully synthesized using the conventional solid-state reaction method and sintered at 1,175℃ for 2 h. The average grain size of the BNT-BF-100x ceramics decreased with increasing ST content. Furthermore, we observed that the ferroelectric- relaxor transition temperature (TF-R) decreased with increasing ST content, which eventually vanished in the BNT-BF-24ST ceramics. The results indicated that a ferroelectric to relaxor phase transition could be induced by ST modification. Consequently, a large electromechanical strain of 633 pm/V at 4 kV/mm was observed for the BNT-BF-26ST ceramics. These results imply that our materials have the competitive advantage of larger strain under lower operating field conditions compared with other BNT-based lead-free piezoelectric ceramics. We expect that BNT-BF-ST lead-free piezoelectric ceramics are promising candidates as a novel ternary BNT-based system and can find potential applications in actuators.
이상섭,이창헌,즈엉 짱 안,김동혁,김병우,한형수,이재신,Lee, Sang Sub,Lee, Chang-Heon,Duong, Trang An,Kim, Dong Hyeok,Kim, Byeong Woo,Han, Hyoung-Su,Lee, Jae-Shin 한국재료학회 2021 한국재료학회지 Vol.31 No.10
(Bi<sub>1/2</sub>Na<sub>1/2</sub>)TiO<sub>3</sub> (BNT)-based ceramics are considered promising candidates for actuator application owing to their excellent electromechanical strain properties However, to obtain large strain properties, there remain several issues such as thermal stability and high operating fields. Therefore, this study investigates a reduction of operating field in (0.98-x)Bi<sub>1/2</sub>Na<sub>1/2</sub>TiO<sub>3</sub>-0.02 BiAlO<sub>3</sub>-xSrTiO<sub>3</sub> (BNT-2BA-100xST, x = 0.20, 0.21, 0.22, 0.23, and 0.24) via analyses of the microstructure, crystal structure, dielectric, polarization, ferroelectric and electromechanical strain properties. The average grain size of BNT-${\underline{2}}$BA-100xST ceramics decreases with increasing ST content. Results of polarization and electromechanical strain properties indicate that a ferroelectric to relaxor state transition is induced by ST modification. As a consequence, a large electromechanical strain of 592 pm/V is obtained at a relatively low electric field of 4 kV/mm in 22 mol% ST-modified BNT-2BA ceramics. We believe that the materials synthesized in this study are promising candidates for actuator applications.
비스무스계 무연 압전세라믹스의 저전계 변형특성 향상을 위한 세라믹/세라믹 복합소재 기술
한형수(Hyoung-Su Han),즈엉 짱 안(Trang An Duong),안창원(Chang Won Ahn),조욱(Wook Jo),이재신(Jae-Shin Lee) 한국세라믹학회 2020 세라미스트 Vol.23 No.1
Abnormally large electromechanical strain properties have been reported in bismuth-based piezoelectric ceramics, which cast a promise for replacing the market-dominating PZT-based piezoelectric ceramics in actuator applications. In spite of these large strains in bismuth-based piezoelectric ceramics, there still remains a critical issue for its safe transfer to practical applications, representatively, a relatively high operating field required to obtain the large strain properties. To overcome the challenge, much attention has been paid to so-called 0-3(or 3-0) type ceramic/ceramic composite approach to better tailoring the strain properties of bismuth-based piezoelectric ceramics. The approach turns out to be highly effective, leading to a drastic decrease in the operating electric field for these materials. Besides, both extensive and intensive search for the related mechanism revealed that the reduction in the operating electric field is largely due to the contribution from polarization coupling or strain coupling model between two different ceramics. This article reviews the status of the art in the development of novel ceramic/ceramic composites to make large incipient piezostrains in bismuth-based lead-free piezoelectric ceramics practical.