• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 추계학술대회 논문집 Vol.21
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• pp.30-30
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• 2008

Lead-free piezoelectric ceramics 0.97$(Na_{0.5}K_{0.5})NbO_3$-0.03Ba$(Ti_{1-x}Sn_x)O_3$ [NKN-BTS-x] ceramics doped with 1 mol% $MnO_2$ have been fabricated by a sintering technique with muffling. The $MnO_2$-doped NKN-BTS-x ceramics with x$\leq$0.2 have pure orthorhombic perovskite structure at room temperature. The dense microstructure was developed with grain growth as an increase of amount of Sn. Moreover, the addition of Sn was found to have a significant influence on piezoelectric properties. In particular, the $MnO_2$-doped NKN-BTS-0.1 ceramics showed improved piezoelectric properties of piezoelectric constant ($d_{33}$=145pC/N), relatively large electromechanical coupling factor ($k_p$=43%), dielectic constant (${\varepsilon}^T_{33}/{\varepsilon}_0$=676) dielectric loss (tan$\delta$=1.3%).

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 추계학술대회 논문집 전기물성,응용부문
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• pp.100-102
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• 2001

In this paper, the piezoelectric and dielectric properties of $Pb(Zr_xTi_{1-x)O_3$ - $Pb(Co_{1/3}Nb_{1/3})O_3)$ piezoelectric ceramics have been investigated as a function of Zr/Ti mole ratio. From the results, when Zr/Ti mole ratio is 49/51, electromechanical coupling coefficient($k_p$), piezoelectric strain constant($d_{33}$) mechanical quality factor($Q_m$), and Permittivity(${{\varepsilon}_{33}}^T/{\varepsilon}_0$) is 64[%], 469[PC/N], 360 and 2000, respectively. Morphotropic Phase Boundary is Zr/Ti mole ratio(49/51) from XRD analysis. Also. From SEM observation, when sintering temperature is 1150[$^{\circ}C$], grain size is about $1{\sim}2[{\mu}m]$ and maximum sintering density is 7.85[$g/cm^3$].

• 대한전기학회논문지
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• 제41권5호
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• pp.517-524
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• 1992

In this study, 0.10Pb(SbS11/2TSnS11/2T)OS13T-(0.90-x)PbZrOS13T (0.25 x 0.40) ceramics were fabricated by the atmospheric method. The sintering temperature and time were 1250[$^{\circ}C$] and 2[2hr], respectively. The structureal, dielectric and piezoelectric properties with composition of PbTiOS13T were studied. As the results of XRD ans SEM, the crystal structure of a specimen was rhombohedral, lattice constant and average grain size were decreased with increasing the contents of PbTiOS13T. Relative dielectric constant and Curie temperature were increased with increasing the contents of PbTiOS13T, 0.10PSS-0.40PT-0.50PZ specimen had the highest values of 904 and 265[$^{\circ}C$], respectively. In increasing of PbTiOS13T contents form 25[mol%] to 40[mol%], piezoelectric charge constant and electromechanical coupling factors were increased form 114[pC/N] to 142[pC/N], 17[%] to 24[%] and mechanical quality factor were decreased with increasing the contents of PbTiOS13T. In the 0.10PSS-0.40PT-0.50PZ specimens, those values were 14.2[kV/cm] and 9.43[x10S0-6TC/cmS02T], resectively.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2009년도 춘계학술발표대회
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• pp.33.1-33.1
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• 2009

Lead-free (1-x)$(Na_{0.5}K_{0.5})NbO_3$-xBa($Ti_{0.9}Sn_{0.1})O_3$ [NKN-BTS-100x] ceramics doped with 1 mol% $MnO_2$ have been prepared by the conventional solid state method and their structural and piezoelectric properties were investigated. The NKN-BTS-100x ceramics exhibited a dense and homogeneous microstructure when they were sintered at $1030-1150^{\circ}C$. Grain growth was observed for the specimen sintered at relatively low temperature of $1050^{\circ}C$. A tetragonal/orthorhombic morphotropic phase boundary (MPB) in the perovskite structure was also appeared for the NKN-BTS-100x ceramics (0.04$1050^{\circ}C$. The enhanced piezoelectric properties in the NKN-BTS ceramics with a MPB composition were obtained. Especially, for the NKN-BTS-6 ceramics, a high dielectric constant (${\varepsilon}^T_3/\varepsilon_0=1,400$), piezoelectric constant ($d_{33}=237$) and electromechanical coupling factor ($k_p=0.42$) were obtained.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 하계학술대회 논문집
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• pp.689-692
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• 2001

In this paper, the pizoelectric and dielectric properties of 0.95Pb(ZrxTil-x)O$_3$- 0.05Pb(Mn$\_$0.2/Fe$\_$0.4/W$\_$0.4/)O$_3$piezoelectric ceramics is investigated as a function of Zr/Ti mole ratio. Also, MPB(Morphotropic Phase Boundary) and optimal sintering temperature is studied using XRD and SEM. As a results, when Zr/Ti mole ratio is 52/48, electromechanical coupling factor, k$\_$p/, is 58[%], permittivity, $\varepsilon$$\^$T/$\_$33//$\varepsilon$0, is 1360 and piezoelectric strain constant, d$\_$33/ is 265[pC/N] and the piezoelectric and dielectric properties become maximum. Phase transition temperature of its ternary piezoelectric system is about 350[$^{\circ}C$]. From the XRD analysis, when Zr/Ti mole ratio is 52/48, tetragonal phase transits to rhombohedral phase. Also, From measuring results of the sintering density, when sintering temperature is 1050[$^{\circ}C$], sintering density become maximum and is about 7930[kg/㎥], and average grain size is about 2-3[$\mu\textrm{m}$].

• 한국전기전자재료학회논문지
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• 제18권2호
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• pp.136-141
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• 2005

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.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 하계학술대회 논문집 Vol.8
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• pp.306-306
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• 2007

최근, LED 구동 인버터, DC-DC 컨버터, AC-DC 컨버터 및 형광등 ballaster 등의 고전압전원장치등에 압전변압기를 적용하고자 하는 연구가 활발히 진행되고 있다. 순수한 $PbTiO_3$는 큐리온도($490^{\circ}C$)가 높고, 기계적강도가 크며, 비유전율(약 200 정도)이 작다. 또한, 두께방향 진동의 전기기계 결합계수 ($K_t$)가 윤곽진동의 전기기계 결합계수($K_p$)보다 크므로 두께방향의 진동모드를 이용한 벌크파 진동자의 경우 윤곽진동방향으로 불요신호(spurious signal)가 적고, 작은 grain size($1\;{\mu}m$정도)로 미세가공이 가능하여 고주파 재료로 이용되고 있다. 압전변압기의 출력 전력을 향상시키기 위해서는 적층으로 제작하여야 하는데 적층 압전변압기 제작시 층간의 내부 전극이 도포된 상태에서 소결하여야 한다. 이때 소걸 온도가 높으면 Pd 함랑이 높은 전극을 사용하여야 하는데 Pd 전극의 가격이 비싸 소자의 경제성이 떨어지게 된다. 따라서 순수한 Ag 전극을 내부전극으로 사용하기 위해서는 $900^{\circ}C$ 이하에서 소결이 가능하여야 한다. 따라서 본 연구에서는 $(Pb,Ca,Sr)Ti(Mn,Sb)O_3$ 조성을 이용하여 $900^{\circ}C$ 이하의 저온소결이 가능한 두께방향진동모드 적층 압전변암기를 제작하여 그에 대한 전기적 특성을 조사하였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 하계학술대회 논문집 Vol.7
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• pp.271-271
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• 2006

The structural, dielectric and piezoelectric properties of $[Bi_{1-x}(Na_{0.7-x}K_{0.2}Li_{0.1})]_{0.5}BaxTiO_3$ (BNKLBxT) ceramics were studied for the compositional range, x = 0-0.08. The samples were prepared by conventional sintering technique. The result of X-ray diffraction (XRD) suggest that $Ba^{2+}$ diffuse into the $[Bi(Na_{0.7}K_{0.2}Li_{0.1})]_{0.5}TiO_3$ (BNKLT) lattices to form a solid solution with a single phase perovskite structure. The ceramic show excellent piezoelectric and ferroelectric properties, and optimum properties measured are as follows: piezoelectric constant $d_{33}=230pC/N$, planar electromechanical coupling factor $k_p\;=\;40.3%$, remanent polarization $P_r\;=\;30\;{\mu}C/cm^2$, and coercive field $E_c\; =\;2.5\;kV/mm$, respectively.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2005년도 하계학술대회 논문집 Vol.6
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• pp.68-69
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• 2005

Low temperature ($\leq900^{\circ}C$) sintering piezoelectric ceramics $0.01Pb(Mg_{1/2}W_{1/2})O_3$-0.41Pb$(Ni_{1/3}Nb_{2/3})O_3-0.35PbTiO_3-0.23PbZrO_3+0.1wt%Y_2O_3+xwt%ZnO$ $(0{\leq}x{\leq}2.5)$ have been developed and investigated. The electromechanical coupling coefficient ($k_p$), piezoelectric constant ($d_{33}$), and mechanical quality factor ($Q_m$) have been measured to characterize the piezoelectric materials system. When 2.0 wt% ZnO is added, the properties of the system, $d_{33}$ = 559 pC/N, $k_p$ = 55.0 % and $Q_m$ = 73.4 are obtained which are very suitable for piezoelectric actuators. A bending mode multilayer actuator has been also developed using the materials which size is $27(L)\times9(W)\times1.07(t)mm^3$. The actuators are fabricated by multilayer ceramic (MLC) process and consist of24 layers and each layer thickness is $35{\mu}m$. At this time, the displacement of actuator was $100{\mu}m$ at 28V.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 D
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• pp.1726-1728
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• 1999

Dielectric and piezoelectric properties of xPb$(Al_{1/2}Ta_{1/2})O_3$-(1-x)Pb$(Zro_{0.52}Ti_{0.48})O_3$ system were investigated. The highest density of $7.80g/cm^3$ for PAT-PZT ceramics of 5mol% PAT was obtained. The relative permittivity of PAT-PZT ceramics of 5mol% PAT was 1.642 at room temperature. The maximum value of electromechanical coupling factor $k_p$ of 55% and $k_t$ of 33% were obtained at the composition of 5mol% PAT. The grain sizes were reduced by increasing the amount of PAT, however mechanical quality factor$(Q_m)$ had a minimum value of 44 at the composition of 5mol% PAT.