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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.
선형 가변 차동 변압기를 이용한 강유전 세라믹의 전기장 인가에 따른 변형 측정
한형수 ( Hyoung-su Han ),안창원 ( Chang Won Ahn ) 한국전기전자재료학회 2024 전기전자재료학회논문지 Vol.37 No.2
강유전체, 압전체 및 전왜 재료의 전기-기계적 반응의 기본 원리를 이해하기 위해 전기장 인가에 따른 변형 측정법은 널리 사용되고 있다. 특히, 전기 자극에 반응하는 압전 재료의 변형 특성을 이해하는 것은 압전 액츄에이터, 음향 장치, 초음파발생기와 같은 부품을 연구하고 개발하는 데 중요하다. 이 튜토리얼 논문에서는 다양한 산업 분야에서 널리 사용되는 변위 측정 장치인 선형 가변 차동 변환기(linear variable differential transducer, LVDT)의 구성 요소와 작동 원리를 소개한다. 또한 전기장을 인가하여 강유전체, 압전체 또는 전왜 재료의 변형 특성을 측정하기 위해 LVDT를 사용하는 실험 장치의 구성을 소개한다. 그리고 이 논문에는 LVDT 실험 장치를 통해 얻은 간단한 측정 결과와 분석이 포함되어 있어서 다양한 재료의 전기-기계 상호 작용 연구 방법에 대해 유용한 정보를 제공한다. The measurement of strain under an electric field has been widely employed to comprehend the fundamental principles of electro-mechanical responses in ferroelectric, piezoelectric, and electrostrictive materials. In particular, understanding the strain properties of piezoelectric materials in response to electrical stimulation is crucial for researching and developing components such as piezoelectric actuators, acoustic devices, and ultrasonic generators. This tutorial paper introduces the components and operational principles of the linear variable differential transducer (LVDT), a widely used displacement measurement device in various industries. Additionally, we present the configuration of an experimental setup using LVDT to measure the strain characteristics of ferroelectric, piezoelectric, or electrostrictive materials under the application of an electric field. This paper includes simple measurement results and analyses obtained through the LVDT experimental setup, providing valuable information on research methods for the electro-mechanical interactions of various materials.
김성현,이상훈,한형수,이재신,Kim, Seong-Hyun,Lee, Sang-Hun,Han, Hyoung-Su,Lee, Jae-Shin 한국전기전자재료학회 2019 전기전자재료학회논문지 Vol.32 No.1
In this study, we investigated the optimum calcination temperature of lead-free $0.74(Bi_{0.5}Na_{0.5})TiO_3-0.26SrTiO_3$(BNST) piezoelectric ceramics by analyzing the crystal structure, dielectric properties, and electric field-induced strain behavior. BNST ceramics prepared by conventional solid-state reaction methods at various calcination temperatures according to the industrial standard. All samples of BNST ceramics were subsequently sintered at $1,175^{\circ}C$ for 2 h. Crystal structure classification of the ceramics showed a single perovskite phase, with no second phase detectable for the samples calcined at $750^{\circ}C$ or higher. BNST samples calcined at $850^{\circ}C$ exhibited the most optimal values for itsand the common physical parameters of $density=5.518g/cm^3$, ${\varepsilon}=1,871.837$, $tan{\delta}=0.047$, and ${d_{33}}^*=874pm/V$.
정광휘,이상섭,안창원,한형수,이재신,Jeong, Gwang-Hwi,Lee, Sang-Seop,Ahn, Chang Won,Han, Hyoung Su,Lee, Jae-Shin 한국전기전자재료학회 2020 전기전자재료학회논문지 Vol.33 No.5
This study investigated the low temperature sintering with various templates of Bi-based lead-free piezoelectric ceramics. The effects of using CuO-coated Na<sub>0.5</sub>Bi<sub>4.5</sub>Ti<sub>4</sub>O<sub>15</sub> templates on the sintering behavior as well as the dielectric, ferroelectric, and piezoelectric properties of Bi<sub>1/2</sub>(Na<sub>0.78</sub>K<sub>0.22</sub>)<sub>1/2</sub>TiO<sub>3</sub> (BNKT) ceramics have been examined. In comparison with the specimens sintered with the Na<sub>0.5</sub>Bi<sub>4.5</sub>Ti<sub>4</sub>O<sub>15</sub> templates without CuO coating, those sintered with the CuO-coated Na<sub>0.5</sub>Bi<sub>4.5</sub>Ti<sub>4</sub>O<sub>15</sub> templates showed larger template sizes as well as a larger electric field induced strain (S<sub>max</sub>/E<sub>max</sub>) of 422 pm/V after sintering at temperatures as low as 975℃. These results are promising for low-cost multilayer ceramic actuator applications.
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.
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.