• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 추계학술대회 논문집
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• pp.77-77
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• 2009

$Pb(Zr,Ti_O_3$계 세라믹스는 우수한 압전 특성으로 인하여 압전변압기 및 액츄에이터, 센서 등 많은 분야에 응용이 되어져 왔다. 그러나, 최근 들어 $1000^{\circ}C$에서 급속도로 많은 휘발을 하는 PbO는 환경 및 인체에 나쁜 영향을 미칠 뿐 아니라 사용 후의 처리도 어려워 선진국에서는 사용을 제한하거나 줄이고 있는 추세에 있다. 따라서, PbO를 포함하지 않은 무연 (Lead-free)계 압전 세라믹스에 대한 연구가 많은 관심을 끌고 있으며 앞으로는E 장래성 있는 하나의 이슈 분야가 될 것이다. 이러한 Pb-based System 세라믹스를 대체 할 재료로서 $(Bi_{1/2}Na_{1/2})TiO_3$나 Tungsten-Bronze type, $(K_{1/2}Na_{1/2})NbO_3$ 등이 주로 연구가 되고 있다. 특히, alkali niobate를 기초로 한 $(K_{1/2}Na_{1/2})NbO_3(NKN)$은 무연 압전 물질로서 많은 주목을 받고 있다. 그러나, NKN의 주요 성분인 K 의 높은 조해성 때문에 일반적인 고상방법으로는 고 밀도의 세라믹을 얻기 힘들뿐더러 낮은 상전이 온도 때문에 많은 응용에는 제약이 되고 있다. 이러한 세라믹의 단점을 보완하고자 Hot forging, RTGG, SPS 등 과 같이 특수한 소결방법을 사용하여 고밀도의 세라믹을 제작하지만 이 방법들은 제품 대량 생산에 있어 경제적으로나 복잡한 제조과정을 고려할 때 매우 비효율적이라고 판단된다. 그러므로 $BaTiO_3$, $LiTaO_3$, Mg, Ca등을 첨가 시켜 소결을 향상시키고 고밀도를 얻기 위해 많은 연구가 진행 중이다. 따라서 본 연구에서는 Pb-based계의 세라믹스를 대체할 우수한 특성의 세라믹스를 제작하고자 기존의 $(K_{1/2}Na_{1/2})NbO_3(NKN)$세라믹스에서 낮은 용융온도 때문에 소결하기 어려운 $KNbO_3$를 제거한 $NaNbO_3$에 $LiNbO_3$와 $BaTiO_3$를 추가한 $NaLiNbO_3-BaTiO_3$세라믹스에 $K_4CuNb_8O_{23}$(KCN)을 첨가함으로서 이에 따른 압전 및 유전 특성을 조사하였다.

• 센서학회지
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• 제17권6호
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• pp.418-424
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• 2008

The PZT based piezoelectric thick films prepared by screen printing method have been mainly used as a functional material for MEMS applications due to their compatibility of MEMS process. However the screen printed thick films generally reveal poor electrical and mechanical properties because of their porous microstructure. To improve microstructure we mixed attrition milled powder with ball milled powder of 0.01Pb$(Mg_{1/2}W_{1/2})O_3$-0.41Pb$(Ni_{1/3}Nb_{2/3})O_3$-$0.35PbTiO_3$-$0.23PbZrO_3$+0.1 wt% ${Y_2}{O_3}$+1.5 wt% ZnO composition. By mixing 25 % of attrition milled powder and 75 % of ball milled powder, the broadest particle size distribution was obtained, leading to a dense thick film with crack-free microstructure and improved dielectric properties. The X-ray diffraction analysis revealed that the film was in wellcrystallized perovskite phase. The remanent polarization was increased from $13.7{\mu}C/cm^2$ to $23.3{\mu}C/cm^2$ at the addition of 25 % attrition milled powder.

• 한국전기전자재료학회논문지
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• 제21권8호
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• pp.755-759
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• 2008

For the development of a new white dielectric layer in plasma display panel, different $TiO_2$ types as a filler was add to the $Bi_2O_3$-BaO-ZnO glass matrix. The reflectance and dielectric constant of dielectric have been investigated as a function of the mixing content (rutile and anatase), and sintering temperature. The reflectance of dielectric sintered at the 520$^{\circ}C$ appeared most highly and suitable in terms of the adhesion and reflectance of the soda-lime glasses. Also, the thermal expansion coefficient of dielectric was found to be $85.6\times10^{-7}/K$, which was similar to that of the soda-lime glasses. Especially, the dielectric constants were not increased with increasing of $TiO_2$ filler contents.

• 한국전기전자재료학회논문지
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• 제17권8호
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• pp.830-834
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• 2004

In this study, lead-free pirzoelectric ceramics were investigated for pressure sensor applications as a function of the amount of ${La}_2{O}_3$ addition at $Bi(Na, K)Ti{O}_3-SrTi{O}_3$system. With increasing the amount of addition, the density and dielectric constant increased up to 0.9 wt% ${La}_2{O}_3$ addition and decreased above 0.9 wt% ${La}_2{O}_3$addition. Electromechanical coupling factor( $K_{P}$) showed the maximum value at 0.2 wt% ${La}_2{O}_3$addition and decreased above 0.2 wt% ${La}_2{O}_3$ addition. Electromechanical coupling $factor{(K)}_P$, density, dielectric constant$(\varepsilon_\Gamma)$, piezoelectric constant$(d_33)$ and curie temperature$(T_C)$ showed optimum value of 0.40, 5.75 g/㎤, 768, 215 pC/N and 320 $^{\circ}C$ at 0.2 wt%${La}_2{O}_3$addition, respectively.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 하계학술대회 논문집 Vol.5 No.2
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• pp.590-594
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• 2004

In this study, lead-free piezoelectric ceramics were investigated for pressure sensor applications as a function of the amount of $CeO_2$ addition at Bi(Na,K)$TiO_3-SrTiO_3$ system. With increasing the amount of $CeO_2$ addition, the density and dielectric constant increased. Electromechanical coupling factor($k_p$) showed the maximum value(kp, 0.39) at 0.1wt% $CeO_2$ addition and decreased above 0.1wt% $CeO_2$ addition., Density, dielectric constant(${\varepsilon}_r$) increased but mechanical quality factor(Qm), piezoelectric constant(d33) decreased in $CeO_2$ addition, respectively.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 추계학술대회 논문집
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• pp.276-276
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• 2007

기존에 전자부품들에 사용되어 온 봉착용, 결합용, 코팅용 유리들은 타유리와 비교하여 낮은 융점을 가지고 있으면서도 열처리 전후에 물리, 화학적으로 매우 안정한 특성을 가지고 있는 PbO를 50~85% 이상 함유한 유리들이 대부분을 차지해왔다. 그러나 PbO 성분은 산성비 등의 산에 용해되어 Pb이온이 생성되면서 환경오염의 원인이 되기 때문에 유해성분으로 규정하고 있다. 최근 유해물질의 규제가 강화됨에 따라 PbO를 대체할 수 있는 $B_2O_3,\;Bi_2O_3,\;V_2O_5,\;P_2O_5$ 등의 새로운 조성의 유리에 대한 연구가 활발히 진행되고 있다. 본 연구에서는 봉착용으로 사용되는 인산계 유리에서 RO계 첨가에 따른 TMA와 고온현미경, 필테스트를 통하여 접합성 및 열적특성 등의 변화에 대하여 조사하였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 추계학술대회 논문집
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• pp.12-12
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• 2009

We weal know that PbO was poisonous and prone to volatilize, then to pollute the circumstance and hurt to people, so we should dope other innocuous additives instead of lead to increase Tc of composite PTC material. In order to prepare lead-free $BaTiO_3$-based PTC with middle Curie point, the incorporation on $(BaNaK)(TiNb)O_3$ into $BaTiO_3$-based ceramics was investigated on samples containing 0.05, 0.07 and 0.1mol% of $(BaNaK)(TiNb)O_3$. $(BaNaK)(TiNb)O_3$ was compounded as standby material by conventional solid-state reaction technique. The starting materials were $Na_2O_3$,$K_2CO_3$, $BaCO_3$, $TiO_2$ and $Nb_2O_5$ powder, and using solid-state reaction method, too. The microstructure of samples were investigated by SEM, DSC, XRD and dielectric properties. Phase composition and lattice parameters were investigated by X-ray diffraction. Also, we are measure the resistivity of sintered bodies with calcinations condition.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2005년도 추계학술대회 논문집 Vol.18
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• pp.218-219
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• 2005

In this paper, in order to develop Pb-free piezoelectric ceramics, $[Li_{0.04}(Na_{0.44}K_{0.52})-(Nb_{0.86}Ta_{0.10}Sb_{0.04})]O_3$ ceramic was fabricated with the variation of ZnO addition. Piezoelectric properties of the ceramic were varied with the amount of ZnO addition and showed the maximum kp value at 0.2 wt% ZnO addition. Qm of ZnO added ceramics showed lower values than the non-added ceramics, however, the kp was increased by the addition of ZnO up to 0.2 wt%. At the sintering temperature of 1110$^{\circ}C$ and the calcination temperature of 850$^{\circ}C$, the optimal values of density=473g/$cm^3$, kp=0.473, $\varepsilon_r$=1403 were obtained.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2005년도 하계학술대회 논문집 Vol.6
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• pp.305-306
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• 2005

In this paper, in order to develop Pb-free piezoelectric ceramics, $(Li_{0.04}Na_{0.44}K_{0.52})(Nb_{0.86}Ta_{0.10}Sb_{0.04})O_3$ ceramics were fabricated with the variation of calcination temperature and sintering temperature. Specimens couldn't be sintered below $111^{\circ}C$ and showed the largest density at calcination temperature of $800^{\circ}C$. Specimens manufactured with the variation of calcination temperature showed pseudo-tetragonal phase, and showed the optimal values of kp=0.45, ${\varepsilon}r$=1336 and $d_{33}$=254 at calcination temperature of $800^{\circ}C$ and sintering temperature of $1110^{\circ}C$.

• 한국세라믹학회지
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• 제31권11호
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• pp.1315-1322
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• 1994

In this study, stable PbTiO3 coating solution was prepared using diethanolamine(DEA) complexing agent and deposited on indium-tin oxide(ITO) coated glass substrate. Prepared thin films were dense and crack-free. Perovskite-type PbTiO3 thin films could be obtained above 50$0^{\circ}C$, while the films heat-treated above $650^{\circ}C$ showed undesired properties due to interface reactions between films and substrates and warpage phenomena of substrates. Measured maximum dielectric constant and loss tangent were found to be 144 and 0.0163 at 1 kHz, 55$0^{\circ}C$ heat-treatment, respectively.