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이형규,강형원,최지현,Lee, Hyeung-Gyu,Kang, Hyung-Won,Choi, Ji-Hyun 한국세라믹학회 2005 한국세라믹학회지 Vol.42 No.10
Dielectric and Piezoelectric properties of complex perovskite 0.92Pb($Zr_{1/2}Ti_{1/2})O_{3}-(0.08-x)Pb(Cu_{1/3}Nb_{2/3})O_{3}-xPb(Mn_{1/3}Nb_{2/3})O_{3}(0{\leq}x{\leq}0.080$) (PZT-PCN-PMN) system were investigated as a function of PMN content. With the increase of PMN content of the sintered specimens, tetragonal phase was coexisted with rhombohedral phase, the dielectric constant was decreased, mechanical quality factor ($Q_{m}$) was inceased, and optimal sintering temperature was increased up to 1050$^{\circ}C$. For the composition of x = 0.064 sintered at 1050$^{\circ}C$ for 2 h, 1939 of maximum mechanical quality factor ($Q_{m}$), 57$\%$ of electromechanical coupling factor ($k_{p}$), and 1100$^{\circ}C$ of dielectric constant, 0.37$\% $ of dielectric loss (tan $\delta$) were obtained.
내부전극패턴 변경에 따른 적층형 압전 액추에이터의 유한요소해석
이형규,강형원,Lee, Hyeung-Gyu,Kang, Hyung-Won 한국전기전자재료학회 2005 전기전자재료학회논문지 Vol.18 No.12
New piezoelectric actuator design, which can reduce the number of the stacking layer without lowering the piezoelectric displacement, is suggested in this work. Each layer of the new designed multilayer actuator has the same electrode pattern as the cross-sectioned layer of the existing multilayer actuator has. The piezoelectric displacement was calculated by Finite-Element Method (FEM) analysis. The maximum piezoelectric displacement of the new-designed actuator with 13 layers was calculated to be almost same value (55.9 ${\mu}m$) as that of the existing actuator with 25 layers(60.1 ${\mu}m$).
강형원,최용준,이형규,Kang, Hyung-Won,Choi, Yong-Jun,Lee, Hyeung-Gyu 한국전기전자재료학회 2007 전기전자재료학회논문지 Vol.20 No.8
The new design of inchworm-type piezoelectric actuator is presented in this paper, Compared to conventional inchworm-type actuators, which are composed of more than three piezoelectric bodies, we can reduce the number of piezoelectric bodies by employing the proposed design, resulting in only one piezoelectric body. The overall size of the proposed actuator which consists of one piezoelectric body, two clamping parts and one extending part, is only $5{\times}6{\times}9 [mm^3]$ (DWL). The actuating characteristics of fabricated Monolithic Inchworm Type Actuator(MITA), were found to be a displacement of $0.3{\mu}m$, a generating force of 0.6N and an electric power of 0.5W.
최진홍,김현아,한승호,강형원,이형규,김정석,천채일,Choi, Jin-Hong,Kim, Hyun-Ah,Han, Seung-Ho,Kang, Hyung-Won,Lee, Hyeung-Gyu,Kim, Jeong-Seog,Cheon, Chae-Il 한국전기전자재료학회 2012 전기전자재료학회논문지 Vol.25 No.9
Recently, many lead-free piezoelectric materials have been investigated for the replacement of existing Pb-based piezoelectric ceramics because of globally increasing environmental interest. There has been remarkable improvement in piezoelectric properties of some lead-free ceramics such as $(Bi,Na)TiO_3-(Bi,K)TiO_3-BaTiO_3$, $(Na,K)NbO_3-LiSbO_3$, and so on. However, no one still has comparable piezoelectric properties to lead-based materials. Therefore, new lead-free piezoelectric ceramics are required. $BiFeO_3$ has a rhombohedrally distorted perovskite structure at room temperature and a very high Curie temperature ($T_C$= 1,100 K). And a very large electric polarization of 50 ~ 60 ${\mu}C/cm^2$ has been reported both in epitaxial thin film and single crystal $BiFeO_3$. Therefore, a high piezoelectric effect is expected also in a $BiFeO_3$ ceramics. The recent research activities on $BiFeO_3$ or $BiFeO_3$-based solid solutions are reviewed in this article.
한승호,박휘열,강형원,이형규,Han, Seung-Ho,Park, Hwi-Yeol,Kang, Hyung-Won,Lee, Hyeung-Gyu 한국전기전자재료학회 2012 전기전자재료학회논문지 Vol.25 No.9
Eco-friendly $(Na,K)NbO_3$ (NKN)-based piezoelectric ceramic materials were fabricated by conventional ceramic method for shear mode piezoelectric energy harvesting application. $NKN-LiTaO_3$ (LT) based compositions were adopted for the high $d_{15}{\times}g_{15}$ which is proportional to harvested energy density. The composition $0.935(Na_{0.535}K_{0.485})NbO_3-0.065LiTaO_3$ was found to be lie on the boundary of tetragonal and orthorhombic phases. With reducing Ta content, the dielectric constant decreased gradually while maintaining high $d_{15}$, which resulted in increased $d_{15}{\times}g_{15}$. The composition $0.935(Na_{0.535}K_{0.485})NbO_3-0.065Li(Nb_{0.990}Ta_{0.010})O_3$ was found to possess excellent piezoelectric and electromechanical properties ($d_{15}{\times}g_{15}=29\;pm^2/N$, $d_{15}$ = 417 pC/N, $k_{15}$ = 0.55), and high curie temperature ($T_c=455^{\circ}C$).
소결 조건이 스크린 인쇄법으로 제조한 PZT계 후막의 물성에 미치는 영향
이봉연,천채일,김정석,김준철,방규석,이형규,Lee, Bong-Yeon,Cheon, Chae-Il,Kim, Jeong-Seog,Kim, Jon-Chul,Bang, Kyu-Seok,Lee, Hyeung-Gyu 한국세라믹학회 2001 한국세라믹학회지 Vol.38 No.10
스크린 인쇄법으로 알루미나 기판 위에 PZT 후막을 제조하였으며, 공기 또는 Pb 분위기의 $750{\sim}1050^{\circ}C$에서 1시간 동안 소결하여 소결 조건이 후막의 물성에 미치는 영향을 조사하였다. 공기 중에서 $950^{\circ}C$ 이상의 온도로 소결한 PZT 후막에는 파이로클로 상이 제 2상으로 존재하고 있었으며, Pb분위기에서 소결한 PZT 후막이 공기 중에서 소결한 후막보다 치밀한 미세구조와 큰 유전상수 그리고 잘 발달된 P-E 이력특성을 보였다. $900^{\circ}C$의 Pb 분위기에서 소결한 PZT 후막은 잘 포화된 전형적인 강유전 P-E 이력곡선 모양을 보였으며, 잔류분극과 항전계가 각각 $29.8{\mu}C/cm^2$, 48.4 kV/cm이었다. PZT thick films were fabricated on alumina substrates by a screen printing method. They were sintered at $750^{\circ}C{\sim}1050^{\circ}C$ for 1 h under air or Pb atmosphere. Pyrochlore was observed as a second phase in PZT thick films sintered in air at temperatures of $950^{\circ}C$ and higher. PZT thick films sintered under Pb atmosphere showed denser microstructure, higher dielectric constant, and better-developed P-E hysteresis curve than the films sintered in air. PZT thick films sintered at $900^{\circ}C$ under Pb atmosphere showed the typical ferroelectric hysteresis with remanent polarization of $29.8{\mu}C/cm^2$ and coercive field of 48.4 kV/cm.
MnO<sub>2</sub> 첨가에 따른 저온소결 PCW-PMN-PZT세라믹스의 유전 및 압전특성
정광현,이덕출,이창배,이상호,류주현,이형규,강형원,Chung, Kwang-Hyun,Lee, Duck-Chool,Lee, Chang-Bae,Lee, Sang-Ho,Yoo, Ju-Hyun,Lee, Hyeung-Gyu,Kang, Hyung-Won 한국전기전자재료학회 2005 전기전자재료학회논문지 Vol.18 No.2
In this study, in order to develop the low temperature sintering ceramics for multilayer piezoelectric transformer, PCW-PMN-PZT ceramics using Li$_2$CO$_3$, Bi$_2$O$_3$, and CuO as sintering aids were manufactured according to the amount of MnO$_2$ addition. Their microstructural, dielectric and piezoelectric properties were investigated. When the sintering aids were added, specimens could be sintered below 95$0^{\circ}C$, but mechanical qualify factor decreased. Therefore, MnO$_2$ was added excessively to the PCW-PMN-PZT ceramics to increase mechanical quality factor. At the sintering temperature of 95$0^{\circ}C$, the density, dielectric constant($\varepsilon$$_{r}$), electromechanical coupling factor(k$_{p}$), mechanical quality factor(Q$_{m}$) and Curie temperature(T$_{c}$) of 0.1 wt% MnO$_2$ added specimen showed the optimal values of 7.75 g/㎤, 1503, 0.57, 1502, and 337, respectively, for multilayer piezoelectric transformer application.ation.n.