• 한국전기전자재료학회논문지
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• 제14권7호
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• pp.562-566
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• 2001

The effects of MnO$_2$ addition on the properties in Pb(Mg$_{1}$3/Nb$_{2}$3/)O$_3$ relaxor ferroelectrics were studied in the phase transition temperature range from -4$0^{\circ}C$ to 11$0^{\circ}C$. Specimens were made via solid state processing method. Dielectric properties, piezoelctric properties, electric-field-induced strain were examined to clarify the effect of MnO$_2$ addition in 0.9MN-0.1PT. As the amount of MnO$_2$ increases, the maximum dielectric constant and the dielectric loss decreases. Q$_{m}$ increased by increasing the doping contents of Mn. When 0.5wt% MnO$_2$ was doped, Q$_{m}$ increased from 95 to 480. The electric-filed-induced strain and polarization decreases as the amount of MnO$_2$ increases. From the experimental results, it was suggested that Mn behaves as an ferroelectric domain pinning element.ent.

• The Korean Journal of Ceramics
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• 제5권1호
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• pp.1-11
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• 1999

The effect of aliovalent dopents, $Nb_3O_5$ and MnO, on the grain growth kinetics of 12 mol% ceria stabilized tetragonal zirconia polycrystals (Ce-TZP) was studied. All specimens were sintered at $1550^{\circ}C$ for 20 minutes prior to annealing at different temperatures to study grain growth kinetics. Grain growth kinetics of Ce-TZP and 1 mol% $Nb_2O_5$ doped Ce-TZP (Ce-TZP/$Nb_3O_5$) during annealing at 1475, 1550, and $1600^{\circ}C$ adequately matched with square law $(D^2-D_\;o^2=k_at)$. However, grain growth in 1 mol% MnO suppressed grain growth in Ce-TZP by drag force exerted by $Mn^{+2}$ ions which segregated strongly to the positively-charged grain boundaries of Ce-TZP, $Nb_2O_5$ enhanced grain growth by increasing the concentration of vacancies of $Zr^{+4}$ ion and $Ce^{+4}$ ions. Surface analysis with X-ray photoelectron spectroscopy (XPS) showed the segregation of Mn+2 ions to grain boundaries. The kinetics of grain growth obtained in the base Ce-TZP and the Ce-TZPs with the aliovalent dopants were examined in the context of impurity drag effect and space charge effect.

• 한국전기전자재료학회논문지
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• 제21권10호
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• pp.906-910
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• 2008

$(K_{0.5}Na_{0.5})NbO_3$ (NKN) ceramics doped with $Li_{2}CO_3$ as sintering aids were manufactured in order to develop the low temperature sintering ceramics for piezoelectric device. The sintering aids were proved to lower the sintering temperature of doped NKN ceramics due to the effect of $Na_{2}CO_{3}-Li_{2}CO_3$ liquid phase. All the specimens showed the orthorhombic phase without secondary phase. And also, the piezoelectric properties of specimens were improved with increasing $Li_{2}CO_3$ contents. At sintering temperature of $930^{\circ}C$, the density, electromechanical coupling factor (kp), mechanical quality factor (Qm) and dielectric constant(${\epsilon}_{\gamma}$), piezoelectric constant of 0.3 wt.% $Li_{2}CO_3$ added specimen showed the optimum values of $4.255 g/cm^3$, 0.37, 234, 309, 136 pC/N, respectively.

• 마이크로전자및패키징학회지
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• 제12권4호통권37호
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• pp.339-343
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• 2005

Pt-$SrBi_2Nb_2O_9(SBN)-Pt-Y_2O_3-Si$ 게이트 전계효과 트랜지스터 (MFMISFETs)의 정보저장 특성향상을 위하여 SBN 박막을 산소 플라즈마 내에서 급속열처리 하였다. 그 결과 SBN 박막의 결정크기는 $700^{\circ}C$의 동일한 열처리조건에서 급속열처리한 SBN 결정립의 크기가 전기로 열처리에 의한 SBN 결정립보다 4배 이상 성장하였다. 또한 분극 특성을 비교한 결과 잔류분극은 2배이상 급속열처리 방법으로 제조된 SBN 박막을 이용한 MFMISFET의 메모리윈도우 (memory window)와 on/off상태의 정보저장특성(programming characteristics)은 월등히 향상되었다.

• 한국세라믹학회지
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• 제35권5호
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• pp.505-511
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• 1998

단결정 Si 기판 위에 증착한 Co/Hf과 Co/Nb 이중층으로부터 형성된 Co 실리사이드의 성장기구에 대하여 조사하였다. 두 경우 모두 500$^{\circ}C$ 이상에서 CoSi2가 주로 형성되었으나 그 결정방위의 성장양상은 서로 달랐다. Co/Hf/(100)Si 구조에서는 Si 기판과 에피텍셜 관계를 갖는 결정립과 그렇지 않은 결정립이 서로 혼합되어 성장하였다. 그러나 Co/Nb/(100)Si에서는 처음부터 에피텍셜 관계를 갖지 않는 결정립들만이 형성되었다. 동일한 구조임에도 불구하고 이렇게 내열금속 중간층에 따라 성장된 실리사이드의 결정방위가 달라지는 것으 안정한 반응제어층의 형성 및 고온에서의 그 분해과정과 관련이 있었다. 여러 구성원소들로 이루어진 반응제어층이 고온까지 안정할 경우에는 Co의 확산이동을 균일하게 제어하여 실리사이드의 에피텍셜 성장이 가능하다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2005년도 추계학술대회 논문집 Vol.18
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• pp.216-217
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• 2005

In this paper, in order to develop Pb-free piezoelectric ceramics, $(Li_{0.05}Na_{0.57}K_{0.38})NbO_3$ ceramic was fabricated with the variation of $Bi_2O_3$ addition. Piezoelectric properties of the ceramic were varied with the amount of $Bi_2O_3$ addition and showed the maximum kp value at.0.2 wt% $Bi_2O_3$ addition. Qm of $Bi_2O_3$ added ceramics showed lower values than the non-added ceramics, however, the kp was increased by the addition of $Bi_2O_3$ 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=4.52g/$cm^3$, kp=0.47, $\varepsilon_r$=400 were obtained.

• Transactions on Electrical and Electronic Materials
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• 제13권6호
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• pp.297-300
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• 2012

Lead-free (1-x)$(Na_{0.5}K_{0.5})NbO_3-xLiNbO_3$, i.e., NKN-LNx (x=0.0, 0.1, 0.2, 0.3, 0.4 mol) was prepared using the conventional solid state reaction method. The effects of LN mixing on the ferroelectric properties of NKN-LNx ceramics were studied using a dielectric constant and P-E (Polarization-electric field) measurements. Ferroelectricity was observed in the composition for x approximately varying between 0.0 and 0.4. Minimum remanent polarization $2P_r=5C/cm^2$ was achieved in the composition for x = 0.2. The ferroelectric phase transition temperature $T_C$ increased with increasing LN content. The ferroelectric phase transition of NKN-LNx ($x{\geq}0.1$) is a second-order phase transition, and that of NKN-LNx ($x{\leq}0.2$) is a first-order phase transition. These results indicate that the ferroelectric phase transition temperature of NKN-LNx change from that of second-order to weak first-order phase transition according to the LN content.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2006년도 하계종합학술대회
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• pp.985-986
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• 2006

The epitaxial $KTa_{0.524}Nb_{0.446}Ti_{0.03}O_3$ films with 3% Ti were investigated. Titanium (+4) substitution on the Nb/Ta site should reduce dielectric losses of KTN: Ti film by introducing an acceptor state. This acceptor state traps electrons due to oxygen vacancies that form during oxide film growth. KTN:Ti films were grown using pulsed laser deposition, and then annealed at different temperatures in oxygen ambient. The crystallinity, and surface morphology of KTN:Ti film were investigated using x-ray diffraction, and atomic force microscopy. The dielectric properties of Ti doped KTN films measured for unannealed and annealed films will be reported. Tunability and dielectric loss of as-deposited KTN:Ti film were determined to be 10% and 0.0134, respectively. For films annealed at $800^{\circ}C$ and $900^{\circ}C$, the dielectric loss decreased but with a decrease in tunability as well.

• 한국전기전자재료학회논문지
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• 제24권4호
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• pp.285-289
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• 2011

In this study, lead-free $(K_{0.5}Na_{0.5+X})(Nb_{0.96}Sb_{0.04})O_3+0.2mol%La_2O_3+1.2mol%$ $K_4CuNb_8O_{23}$ (X= 0~0.025) ceramics were fabricated by normal sintering method at $1060^{\circ}C$ for 5 h. Microstructures, piezoelectric and dielectric properties of specimens were investigated with special emphasis in the influence of Na excess addition. The grain size of specimen was slightly decreased with increasing Na content. In the 2 [mol%] Na excess addition of NKNS ceramics, density, electromechanical coupling factor, piezoelectric constant and electromechancal quality factor of specimen were found to reach the optimum values of 4.25 [$g/cm^3$], 0.4357, 154.43 [pC/N] and 580, respectively.

• 한국재료학회지
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• 제12권5호
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• pp.369-374
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• 2002

To investigate the corrosion behavior of Zr-1.0Nb-xSn (x=1.0, 1.5, 2.0 and 2.5wt. %)alloy system, the corrosion tests of Zr-1.0Nb-xSn alloys were carried out in steam at $400^{\circ}C$ for 125 days and in 70ppm LiOH solution at $360^{\circ}C$ for 180 days. The matrix microstructures of the test specimens were analyzed using TEM and the oxide structures on the test specimens were analyzed using XRD. It was found from the analyses that the more Sn content the alloy had, the faster it was corroded and with the increase of Sn content in the alloy the fraction of $t-ZrO_2$ to $m-ZrO_2$ was decreased. It was also found that the alloys having more Sn showed more dislocation density than those having less.