• 한국전기전자재료학회논문지
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• 제14권1호
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• pp.20-25
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• 2001

To develop the piezoelectric actuator, the structural, dielectric and piezoelectric properties and electric fieldinduced strain of the ceramics(Pb$\_$1-2/Ba$\_$x/)[Mg$\_$1/2/W$\_$1/2/)$\_$0.03/-Ni$\_$1/3/Nb$\_$2/3/)$\_$0.12/-(Zr$\_$0.5/Ti$\_$0.5/)$\_$0.85/]O$_3$(x=0, 0.01, 0.03, 0.05, 0.07, 0.1) were investigated with the substitution of Ba. The tetragonality of crystal structure and grain size decreased by the substitution of Ba. Curie temperature decreased due to the decrease of the tetragonality, and dielectric constants increased with the substitution of Ba. The coercive field, remnant polarization and electromechanical coupling factor also decreased, whereas the piezoelectric constatns d$\_$33/ and d$\_$31/ were showed the highest value of 430 and 209(x10$\^$-12/C/N), respectively, because of the increase of dielectric constant. The strain induced by 60Hz AC electric field had the maximum value of 204x10$\^$-6/Δℓ/ℓ at the substitution of Ba 3mol%. As the applied electric field approaches to the coercive field, the piezoelectric element is depolarized and the electric field induced strain revealed non-linearity.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 하계학술대회 논문집 Vol.4 No.2
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• pp.660-663
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• 2003

In this Study, lead-free $Bi_{0.5}(Na_{0.84}K_{0.16})_{0.5}TiO_3$ system ceramics were fabricated with the variations of Sr substitution and their dielectric and piezoelectric characteristics were investigated. With the increase of Sr substitution, dielectric constant increased linearly and Curie temperature decreased slightly. Also, the temperature dependence curve of dielectric constant was moved to left-ward. At 4mol% Sr substitution, Tc of 292, kp of 34.03%, kt of 45.32% and ${\epsilon}r$ of 868 were shown, respectively.

• 한국전기전자재료학회논문지
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• 제21권3호
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• pp.232-235
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• 2008

In this study, in order to develop the composition ceramics for multilayer piezoelectric actuator, PMN-PNN-PZT ceramics were fabricated using $Li_2CO_3$, $Na_2CO_3$, ZnO as sintering aids and their piezoelectric and dielectric properties were investigated according to the Bi substitution, Bi substitution induced grain growth and increase of sinterablity, And also, Bi substitution suppress secondary phase due to the liquid phase sintering effect. Bi substitution enhanced electromechanical coupling factor ($k_p$) and dielectric constant ($\varepsilon_r$), However, mechanical quality factor($Q_m$) was deteriorated, At the sintering temperature of 870 $^{\circ}C$ and Bi substitution of 1 mol%, density, electromechanical coupling factor ($k_p$), mechanical quality factor ($Q_m$), Dielectric constant ($\varepsilon_r$) and piezoelectric constant ($d_{33}$) of specimen showed the optimum values of 7,878 $g/cm^3$, 0,608, 835, 1603 and 397 pC/N, respectively for multilayer piezoelectric actuator application.

• 한국전기전자재료학회논문지
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• 제17권5호
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• pp.492-496
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• 2004

In this study, (0.96 －x)(PSN-PZT)－xBF－0.04 PNW＋0.3wt%MnO$_2$＋0.6wt%CuO ceramics were fabricated with the variations of the amount of BiFeO$_3$substitution and sintering temperature for the development of modified ceramics which can be sintered in the low temperature($\leq$100$0^{\circ}C$ ), and their microstructural, dielectric and piezoelectric characteristics were investigated. As the amount of BiFeO$_3$ substitution was increased, the density, mechanical quality factor(Q$_{m}$) and electromechanical coupling factor(k$_{p}$) showed the maximum value at each of sintering temperature. At sintering temperature of 98$0^{\circ}C$ and BiFeO$_3$substitution of 2 mol%, the density, dielectric constant and electromechanical coupling factor(k$_{p}$) showed the maximum value of 7.84 g/㎤, 1415 and 0.49, respectively. And at sintering temperature of 95$0^{\circ}C$ and BiFeO$_3$substitution of 3mol%, mechanical quality factor showed the maximum value of 1062. 1062.

• 한국전기전자재료학회논문지
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• 제14권5호
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• pp.356-361
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• 2001

The structureal, dielectric and piezoelectric properties of Pb[(Sb$\_$1/2/Nb$\_$1/2/)$\_$x/-(Ni$\_$1/3/Nb$\_$2/3/)$\_$0.15-x/-(Zr$\_$y/Ti$\_$1-y/)$\_$0.85/]O$_3$(x=0∼0.05, y=0.47∼0.52) ceramics were investigated with the substitution of Pb(Sb$\_$1/2/Nb$\_$1/2/)O$_3$(abbreviated PSN) and the Zr/Ti ratio. At Zr/Ti ratio of 50/50, tetragonality was decreased and grain size abruptly decreased with the increase of PSN substitution. Curie temperature was decreased and dielectric constant increased with the substitution of PSN. The coercive field increased and remnant polarization decreased with the substitution of PSN. Electromechanical coupling factor(k$\_$p/) showed the highest value of 0.622 at 1mol% PSN, but mechanical quality factor(Q$\_$m/) showed the minimum value at that composition. Dielectric constant and electromechanical coupling factor with the Zr/Ti ratio showed maximum values at Zr/Ti ratio of 50/50 and mechanical quality factor showed minimum values near the Zr/Ti ratio of 50/50.

• Journal of Magnetics
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• 제7권4호
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• pp.143-146
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• 2002

Mechanical milling technique is considered to be a useful way of processing the fine Nd-Fe-B-type powder with high coercivity. In the present study, phase evolution of the $Nd_{15}(Fe_{1-x}Co_{x})_{77}B_{8}$ (x=0-0.6) alloys during the high energy mechanical milling and annealing was investigated. The effect of Co-substitution on the crystallization of the mechanically milled $Nd_{15}(Fe_{1-x}Co_{x})_{77}B_{8}$ amorphous material was examined. The Nd-Fe-B-type alloys can be amorphized completely by a high-energy mechanical milling. On annealing of the amorphous material, fine $\alpha$-Fe crystallites form first from the amorphous. These fine $\alpha$-Fe crystallites reacts with the remaining amorphous afterwards, leading to crystallization to $Nd_2Fe_{14}$B phase. The Co-substitution for Fe in $Nd_{15}(Fe_{1-x}Co_{x})_{77}B_{8}$ ($\mu$x=0∼0.6) alloys lower significantly the crystallization temperature of the amorphous phase to the $Nd_2Fe_{14}$B phase. The mechanically milled and annealed $Nd_{15}Fe_{77}B_8$ alloy without Co-substitution exhibits consistently better magnetic properties with respect to the alloys with Co-substitution.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 춘계학술대회 논문집 반도체 재료 센서 박막재료 전자세라믹스
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• pp.161-164
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• 2004

In this study, to develop the composition ceramics for the Ultrasonic vibrator, $Pb(Mn_{1/3}Nb_{2/3})O_3Pb(Zr.Ti)O_3$ system ceramics were manufactured as a function of PCN substitution. Its dielectric and piezoelectric characteristics were investigated. With increasing the amount of PCN substitution, electromechanical coupling factor(kp) were increased until 3mol% PCN and that after decreased. mechanical quality factor(Qm) showed the maxinum value at 2mol% PCN. Eletromechanical coupling factor, mechanical quality factor and dielectric constant were showed optimum value at PCN 2mol% as 0.58, 1630 and 1407, respectively for ultrasonic vibrator applications.

• Bulletin of the Korean Chemical Society
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• 제33권8호
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• pp.2765-2768
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• 2012

• Composites Research
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• 제32권1호
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• pp.29-36
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• 2019

본 논문의 목적은 소재대체법과 치수최적화 기법을 이용한 2층 고속열차 알루미늄 압출재 차체의 경량 설계를 제시하는 것이다. 소재대체법을 수행하기 위해 위상최적화 기법을 이용하여 차체 구조물의 샌드위치 복합재 적용 부위를 결정하였다. 해석결과, 루프와 2층 언더프레임에 샌드위치 복합재가 적용 가능함을 보여주었다. 치수최적화는 알루미늄 압출재와 카본/에폭시 복합재의 두께를 결정하는데 사용되었다. 치수최적화를 수행하기 위해, 설계변수, 제약조건, 목적함수를 정식화 하였으며 이러한 조건에 의해 유효설계를 도출하였다. 경량 설계의 결과로 2층 고속열차 하이브리드 차체의 무게를 2.18 ton(17.70%)까지 줄일 수 있음을 보여주었다.

• 한국전기전자재료학회논문지
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• 제20권9호
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• pp.766-770
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• 2007

In this study, in order to develop low temperature sintering ceramics for multilayer piezoelectric actuator, $0.07Pb(Mn_{1/3}Nb_{2/3})O_3-xPb(Ni_{1/3}Nb_{2/3})O_3-(0.93-x)Pb(Zr,Ti)O_3$ ceramics system were fabricated using $Li_2CO_3-Bi_2O_3-CuO$ sintering aids and the specimens were sintered at $930^{\circ}C$. Thereafter, their piezoelectric and dielectric characteristics were investigated according to the amount of PNN substitution. At 9 mol% PNN substitution, density, electromechanical coupling factor ($k_p$), dielectric constant, mechanical quality factor ($Q_m$) and piezoelectric constant ($d_{33}$) showed the optimum value of $7.86g/cm^3$, 0.60, 1640, 1323 and 387 pC/N, respectively. It is considered that these values are suitable for piezoelectric divece application such ad multilayer piezoelectric actuator and ultrasonic vibrator with pure Ag internal electrode.