• 한국전기전자재료학회논문지
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• 제18권3호
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• pp.237-242
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• 2005

In this paper, in order to develop the low temperature sintering ceramics for multilayer piezoelectric transformer, PMN-PZT ceramics were manufactured with the variations of sintering times, and their microstructural, piezoelectric and dielectric properties were investigated. Li$_2$CO$_3$ and Bi$_2$O$_3$ were used as sintering aids and the specimens were sintered during 30, 60, 90, 120, 150, and 180 minutes, respectively. At the specimen sintered during 90 minute, mechanical quality factor(Qm), electro-mechanical coupling factor(kp) and dielectric constant were showed the optimum values of 2,356, 0.504 and 1,266, respectively.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 하계학술대회 논문집 Vol.8
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• pp.290-291
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• 2007

In this study, in order to develop the low temperature sintering multilayer piezoelectric actuator, PZW-PMN-PZT system ceramics were manufactured according to variation of sintering aids. At the sintering temperature of $900^{\circ}C$, $0.3wt%Li_2CO_3$, $0.2wt%Bi_2O_3$ and 0.2wt%CuO added specimen showed a maximum value of kp = 0.552, $d_{33}\;=\;344pC/N$ and Qm = 1320, respectively.

• 한국재료학회지
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• 제7권1호
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• pp.40-49
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• 1997

기계적 합금화 공정과 가압소결법으로 $Bi_{2}(Te_{0.9}Se_{0.1})_{3}$ 열전재료를 제조하여, 가압소결온도 및 dopant첨가에 따른 미세구조와 열전특성의변화를 연구하였다. 평균 3.6mm 크기의 Bi, Te, Se granule을 볼과 원료금속의 무게비 5:1에서 3 시간 기계적 합금화 하므로써 $Bi_{2}(Te_{0.9}Se_{0.1})_{3}$ 합금분말의 형성이 완료되었다. $Bi_{2}(Te_{0.9}Se_{0.1})_{3}$ 가압소결체의 성능지수는 $450^{\circ}C$ 이상의 온도에서 가압소결시 급격히 증가하였으며, $550^{\circ}C$에서 가압소결한 시편에서 $1.9{\times}10^{-3}/K$의 값을 얻었다. $550^{\circ}C$에서 가압소결한 $Bi_{2}(Te_{0.9}Se_{0.1})_{3}$의 성능지수는 acceptor dopant 인 Bi를 0.015wt %첨가함에 따라 $2.1{\times}10^{-3}/K$로 향상되었다.

• 마이크로전자및패키징학회지
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• 제6권3호
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• pp.37-43
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• 1999

고주파에서 사용하기 위한 $SiO_2-TiO_2-Bi_2O_3$-RO계(RO:BaO-CaO-SrO)를 주성분으로 하는 결정화 유리와 세라믹 충진재로서 $Al_2O_3$를 혼합하여 제조한 저온 소성용 Glass/Ceramic 유전체 모재와 Ag-thick film의 동시 소결시 발생할 수 있는 소결 부정합과 그 해소 방안을 연구하였다. 적층된 Glass/Ceramic 유전체 sheet와 Ag-thick film의 동시 소결시에 소결체는 sheet와 film의 densification rate 차 등에 의해 큰 camber 현상과 그로 인해 Ag-film에 crack이 발생하였다. 이를 교정하기 위해 유리 성분과 $Al_2O_3$성분이 혼합된 유전체 분말에 $B_2O_3$를 6, 8, 10, 12, 14 vol% 첨가한 결과를 보면 $B_2O_3$첨가량이 증가함에 따라 소결체의 camber 현상은 점점 크게 줄어들었으며 14 vol% 첨가된 경우에는 거의 관찰되지 않았다. 또한 $BaO_3$첨가량이 증가함에 따라 유전율($varepsilon_{r}$)은 점점 감소하였고 Q$\times$f 값은 크게 증가하는 경향을 나타내었으며 $\tau_{f}$ 값은 양(+)의 값으로 점점 크게 변하였다.

• 한국전기전자재료학회논문지
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• 제23권12호
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• pp.929-935
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• 2010

$(1-x)BaTiO_3-x(Bi_{0.5}Na_{0.5})TiO_3$ ($0.01{\leq}x{\leq}0.10$) ceramics were fabricated with muffled sintering by a modified synthesis process. Their positive temperature coefficient of resistivity (PTCR) characteristics were investigated systematically. All specimen showed a perovskite structure with a tetragonal symmetry. Both the lattice parameter of a and c axes were slightly decreased with increasing $(Bi_{0.5}Na_{0.5})TiO_3$ (BNT) content. Grain growth was achieved when the incorporated BNT was increased to 6 mol% and the inhibition of grain growth is considered to be due to the appearance of Ba vacancy ($V^{"}_{Ba}$) in the $(1-x)BaTiO_3-x(Bi_{0.5}Na_{0.5})TiO_3$ ($0.08{\leq}x$). With 4 mol% BNT addition, room temperature resistivity decreased to $48 \Omega{\cdot}cm$ and a resistivity jump ($\rho_{max}/\rho_{min}$) was as high as $1.1{\times}10^4$, respectively. Curie temperature was also increased to $171^{\circ}C$ with increasing BNT content.

• 한국전기전자재료학회논문지
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• 제21권2호
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• pp.126-130
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• 2008

In this study, in order to develop low loss multilayer piezoelectric actuator, PZN-PZT ceramics were fabricated using $Li_2CO_3,\;Bi_2O_3$, CuO and ZnO as sintering aids, their structural, piezoelectric and dielectric characteristics were investigated according to the amount of ZnO addition, At the sintering temperature of $870^{\circ}C$, the density, electromechanical coupling factor(kp), mechanical quality factor(Qm), dielectric constant(${\epsilon}_r$) and piezoelectric constant($d_{33}$) of 0.4 wt% ZnO added specimen (sintered at $870^{\circ}C$) showed the optimum value of $7.812g/cm^3$, 0.535, 916, 1399, 335 pC/N respectively. Taking into consideration above piezoelectric properties of the specimen sintered at low temperature, it was concluded that PZN-PZT ceramics using 0.4 wt% ZnO as additive showed the optimum characteristics as the composition ceramics for low loss multilayer piezoelectric actuator application.

• 한국전기전자재료학회논문지
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• 제20권2호
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• pp.130-134
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• 2007

In this study, in order to. develop the low temperature sintering ceramics for multilayer piezoelectric actuator, PMN-PNN-PZT ceramics using CuO, $Bi_{2}O_{3}\;and\;Li_{2}CO_{3}$ as sintering aids were manufactured with the amount of $WO_{3}$ addition. The ceramics were sintered at $900,\;930,\;960^{\circ}C$, respectively. Thereafter, their microstructural, dielectric and piezoelectric properties were investigated. The $WO_{3}$ was proved to lower the sintering temperature of piezoelectric ceramics due to the effects of PbO and $WO_{3}$ liquid phase. At 0.3 wt% $WO_{3}$ added specimen sintered at $930^{\circ}C$, electromechanical coupling factor($k_{p}$), mechanical quality factor($Q_{m}$), dielectric constant and $d_{33}$ showed the optimum values as the values of 0.60, 1,402, 1,440 and 360 pC/N, respectively, for multilayer piezoelectric actuator application.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 추계학술대회 논문집 Vol.19
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• pp.214-216
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• 2006

In this study, in order to develop the composition ceramics for low loss and low temperature sintering multilayer piezoelectric actuator, PMN-PZN-PZT ceramics were fabricated using two stage calcination method and $Li_2CO_3$, $Bi_2O_3$ and CuO as sintering aids and their piezoelectric characteristics were investigated according to the 2nd calcination and sintering temperature. At the calcination temperature of $750^{\circ}C$ and sintering temperature of $930^{\circ}C$, 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 value of $7.94g/cm^2$ 0.581, 1554, 1555 and 356pC/N, respectively for multilayer piezoelectric actuator application.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 추계학술대회 논문집 Vol.17
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• pp.425-430
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• 2004

In this paper, in order to develop the low temperature sintering ceramics for multilayer piezoelectric transformer, PMN-PZT ceramics were manufactured with the variations of sintering times, and their microstructural, piezoelectric and dielectric properties were investigated. To manufacture multilayer piezoelectric transformer, the low temperature sintering composition is need, hence, $Li_2CO_3$ and $Bi_2O_3$ were used as sintering aids and the specimens were sintered during 30, 60, 90, 120, 150 and 180 minutes, respectively. At the specimen sintered during 90 minute, mechanical quality factor(Qm), electromechanical coupling factor(kp) and dielectric constant were showed the optimum values of 2356, 0.504 and 1266, respectively. All the specimens showed tetragonality phase, and pyrochlore phase was not shown.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 영호남학술대회 논문집
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• pp.185-189
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• 2000

ZnO varistor has many merits as compared with SiC varistor. But, because of leakage current and non-linear coefficient, it has unstable function properties. For the purpose of improvement of ZnO varistor properties, ZnO varistor is studied according to sintering condition and mixing condition. ZnO varistor, $ZnO-Bi_2O_2-Y_2O_3-MnO-Cr_2O_3-Sb_2O_3$ series, is fabricated with $Sb_2O_3$ mol ratio(0.5-4[mol%]) and sintered at $1250[^{\circ}C]$ In accordance with $Sb_2O_3$ mol ratio and sintering temperature, grain size and non-linear coefficient are measured. The specimen, $Sb_2O_3$ mol ratio is 1[mol%], has small grain size. It has best properties because of its liquid phase shape. When $Sb_2O_3$ mol ratio is 1[mol%], grain size is decreased.