• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 하계학술대회 논문집
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• pp.94-98
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• 2000

Polycrystalline SBTN ferroelectric thin films were prepared by sol-gel method with various Nb mole ratios on Pt/ $SiO_2$/Si (100) substrates. The films were annealed at different temperatures and characterized in terms of phase and microstructure. Relatively a well saturated hysteresis pattern was obtained at x =0.2 in S $r_{0.8}$B $i_{2.3}$(T $a_{1-x}$ N $b_{x}$)$_2$ $O_{9+}$$\alpha$/ thin films. At an applied voltage of 5V, the dielectric constant ($\varepsilon$$_{r}$) and dissipation factor (tan $\delta$) of typical S $r_{0.8}$B $i_{2.3}$(T $a_{1-x}$ N $b_{x}$)$_2$ $O_{9+}$$\alpha$/ thin film (x=0.2) were about 236.2 and 0.034. Measured remanent polarization (2Pr) and coercive field (Ec) were 4.28C/c $m_2$, and 38.88kv/cm respectively. No fatigue was observed up to 6$\times$10$_{10}$ switching cycles at 5V and the normalized polarization reduced by a factor of only 4%.%. 4%.%. 4%.%.%.%.%.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2005년도 춘계학술대회 논문집
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• pp.377-382
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• 2005

본 연구에서는 이송장비의 조별운행방식과 Pooling 운행방식에 따른 컨테이너 터미널의 하역시스템 생산성을 비교분석하였다. 기존 컨테이너 터미널에서는 다수의 이송장비가 1개조로 구성되어 하나의 컨테이너 크레인(C/C)에 대해서만 양 ${\cdot}$ 적하작업을 지원하는 고정할당방식을 채택하고 있다. 이러한 할당방식은 하역작업시 혼선이 적고 차량이 일괄적 운행경로를 가지므로 지금까지 매우 광범위하게 적용되어 왔다. 그러나, 각기 다른 조에 편성된 이송장비간에는 상호지원을 하지 않기 때문에 이송장비의 작업융통성이 떨어진다고 볼 수 있다. 이에 비해 본 연구에서는 이송장비의 작업조를 편성하지 않고 투입된 모든 이송장비가 자유롭게 다수의 C/C에 대한 이송작업을 지원할 수 있는 4가지의 동적할당기법을 제시한다. 제시된 4가지의 동적할당은 차량할당시에 C/C의 순번(Se), 대기시간(Qt), 생산성(Pr), 차량할당수(Nv), 버퍼수(Nb)를 고려하는 것으로 연구결과에서 C/C의 현재대기시간, 할당수, 버퍼수를 동시에 고려한 동적할당방식이 가장 효율적이였고, 그 다음으로 할당순서에 기준한 방식이 우수한 결과를 보였다. 그러나, C/C의 현재생산성이나 대기시간만을 고려한 할당방식은 상대적으로 고정할당방식보다 낮은 효율성을 보이는 것으로 나타났다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 하계학술대회 논문집 Vol.5 No.2
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• pp.960-964
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• 2004

[ $Ba_2NaNb_5O_{15}$ ](BNN) thin films have been prepared by the ion beam sputter deposition (IBSD) method on Pt coated Si substrate at temperature as low as $600^{\circ}C$ XRD, SEM were used to investigate the crystallization and microstructure of the films. It was found that the films were crack-free and uniform in microstructure. The electric properties of thin films were carried out by observation of D-E hysteresis loop, dielectric constant and leakage current. It was found the deposition rate strongly influenced the phase formation of the films, where the phase of $BaNb_2O_6$ was always formed when the deposition rate was high. However, the single phase (tungsten bronze structure ) BNN thin film was obtained with the deposition rate as low as $22{\AA}/min$. The remanent polarization Pr and dielectric constant are about 1-2 ${\mu}C/cm^2$ and $100\sim200$, respectively. It was also founded the electric properties of thin films were influenced by the deposition rate. The Pr and dielectric constant of films increased with the decrease of deposition rate. The effects of annealing temperature and annealing time to the crystallization behavior of films were studied. The crystallization of thin film started at about $600^{\circ}C$. The adequate crystallization was gotten at the temperature of $650^{\circ}C$ when the annealing time is 0.5 hour or at the temperature of $600^{\circ}C$ when the annealing time is long as 6 hours.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 추계학술대회 논문집 전기물성,응용부문
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• pp.157-159
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• 2005

In this study, 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 by conventional mixed oxide method and their piezoelectric characteristics were investigated according to the poling condition. The transition temperature from orthorhombic phase to tetragonal phase observed at $93[^{\circ}C]$ and Curie temperature was $346[^{\circ}C]$. At $50[^{\circ}C]$ poling temperature, dielectric constant, electromecha nical coupling factor kp, piezoelectric $d_{33}$ const ant, coercive field Ec, remanant polarization Pr and mechanical quality factor Qm showed the optimum value of 737, 0.45, 209[pC/N], 1l.34[kV/cm], $7.14[{\mu}C/cm^2]$ and 205, respectively.

• 센서학회지
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• 제6권5호
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• pp.392-399
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• 1997

본 연구에서는 $0.125Pb(Mg_{1/2}Nb_{2/3})O_{3}-0.435PbTiO_{3}-0.44PbZrO_{3}$의 조성을 갖는 hard계 압전 재료에 0.5 wt%의 $MnO_{2}$를 첨가하였으며, 이 시편으로 초음파 전동기를 제작하고자, 소결 온도에 따른 시편의 유전 및 압전특성에 대하여 연구하였다. 실험 결과, $1270^{\circ}C$의 소결 온도에서 다음과 같이 가장 우수한 압전특성을 나타냈다. 즉 시편의 밀도는 $7.72\;g/cm^{3}$ 유전상수는 570, 유전손실은 0.82 %f, 잔류분극 Pr은 $19.18{\mu}C/cm^{2}$ 항전계 Ec는 9.63 kW/cm, 전기기계 결합계수 kp는 55.1%, 기계적 품질계수 Qm은 886이 되었다. 또한 $1270^{\circ}C$ 에서 소결된 시편의 유전상수 및 유전손실을 주파수 변화와 온도 변화에 따라 조사하였다.

• Transactions on Electrical and Electronic Materials
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• 제13권4호
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• pp.171-176
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• 2012

As langasite $A_3BC_3D_2O_{14}$ compounds with piezoelectric properties exhibit no phase transition up to the melting point of 1,400-$1,500^{\circ}C$, many high temperature applications are expected for the SAW filter, temperature sensor, pressure sensor, and so on, based on the digital transformation of wider bandwidth and higher-bit rates. It has a larger electromechanical coupling factor compared to quartz and also nearly the same temperature stability as quartz. The $La_3Ga_5SiO_{14}$ (LGS) crystal with the $Ca_3Ga_2Ge_4O_{14}$-type crystal structure was synthesized and the crystal structure was analyzed by Mill et al. It is also an important feature that the growth of the single crystal is easy. In the case of three-element compounds such as $[R_3]_A[Ga]_B[Ga_3]_C[GaSi]_DO_{14}$ (R=La, Pr and Nd), the piezoelectric constant increases with the ionic radius of R. In this study, crystal structures of four-element compounds such as $[A_3]_A[B]_B[Ga_3]_C[Si_2]_DO_{14}$ (A = Ca or Sr, B = Ta or Nb) are analyzed by a single crystal X-ray diffraction, and the mechanism and properties of the piezoelectricity depending on the species of cation was clarified based on the crystal structure.

• Transactions on Electrical and Electronic Materials
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• 제6권1호
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• pp.10-13
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• 2005

$Sr_{0.6}Ba_{0.4}Nb_{2}O_{6}$, hereafter SBN60, thin films of 300 nm thickness were deposited using ion beam sputtering technique, in which sintered ceramic target of the same composition was utilized and the $Ar:O_{2}$ gas ratio was controlled during deposition onto $Pt(100)/TiO_{2}/SiO_{2}/Si$ substrate. Crystallization and orientation behavior as well as electrical properties of the films were examined after annealing treatment at $650{\sim}800{\cric}C$. It was found that the film orientation was dependent upon $Ar:O_{2}$ratio, in which strong (00l) orientation was developed when the gas ratio was about 1:4 at $4.3{\times}10^{-4}$ torr. Typical remanent polarization (2Pr), the coercive field (Ec) and the dielectric constant of Pt/SBN60/Pt thin film capacitor were approximately $10{\mu}C/cm^{2}$, 60 kV/cm, and 615, respectively.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 제5회 영호남 학술대회 논문집
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• pp.85-88
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• 2003

$Sr_xBa_{1-x}Nb_2O_6$(SBN, $025{\leq}x{\leq}0.75$) ceramic is a ferroelectric material with tetragonal tungsten bronze (TTB) type structure, which has a high pyroelectric coefficient and a nonlinear electro-optic coefficient value. In spite of its advantages, SBN has not been investigated well compared to other ferroelectric materials with perovskite structure. In this study, SBN thin film was manufactured by ion beam sputtering technique using the prepared SBN target in Ar/$O_2$ atmosphere. SBN30 thin film of 500 ${\AA}$ was pre-deposited as a seed layer on Pt(l00)/$TiO_2$/$SiO_2$/Si substrate followed by SBN60 deposition up to 4500 ${\AA}$ in thickness. SBN60/SBN30 layer was deposited at different Oxygen amount of 0, 8.1, 17, and 31.8 sccm, respectively. The crystallinity and orientation behavior as well as electric properties of SBN60/SBN30 multi-layer were examined. The deposited layer was uniform and the orientation was shown primarily along (001) plane from XRD pattern. The crystal structure and the electric properties depended on the Oxygen amount, heating temperature and was the best at O2 = 8.1 seem, $750^{\circ}C$. In electric properties of Pt/SBN60/SBN30/Pt thin film capacitor prepared, the remnant polarization (2Pr) value was 13 ${\mu}C/cm^2$, the coercive field (Ec) 75 kV/cm, and the dielectric constant 1492, respectively.

• 암석학회지
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• 제12권3호
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• pp.135-153
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• 2003

선캠브리아기 변성퇴적암류를 관입하고 있는 탄산염암에 배태하는 홍천 철-희토류 광상은 자철석, 안케라이트, 능철석, 마그네사이트, 스트론티아나이트 등의 다양한 탄산염광물과 모나자이트, 아지린휘석, Na가 섬석 및 황화광물들이 산출되어 이들 암석의 지화학적특성과 성인을 규명하고자 주 원소, 미량원소, 희토류원소 및 산소-탄소의 안정동위원소의 광물 및 암석화학연구가 이루어졌다. 각 원소(주원소, 미량원소, 희토류원소)들을 본 연구지역의 탄산염암과 유사한 철질 카보나타이트(ferro-carbonatite)와 비교하면 주 원소에서는 농집된 FeO와 결핍된 CaO가 관찰되며, $SiO_2$가 증가하면서 $TiO_2$와 $A1_2O_3$증가, CaO, FeO, MgO 및 $P_2O_{5}$의 약한 감소가 인지되나 분산되어 뚜렷한 경향은 아니다. 미량원소는 Nb, Zr 및 Zn이 철질 카보나타이트보다 결핍되어 나타나며, $SiO_2$의 증가에 따른 V 및 Ni의 증가, U 및 Rb의 미약한 증가가 확인되나 타 원소들은 분산되어 뚜렷한 경향을 나타내지 않는다. 희토류원소는 전희토류(TREE)함량이 매우 높고 La, Ce, Pr, Nd 및 Sm 같은 경희토류의 농집, 그리고 결핍된 중희토류로 인하여 높은 La/Lu 값을 보이고 있다. 안케라이트, 스트론티아나이트 및 전암의 산소 및 탄소 안정동위원소 결과는 본 암이 화성기원의 카보나타이트용융체에서 유래된 것으로 나타난다. 홍천 철-희토류 광상 탄산염암의 암석화학적 특성은 일반적인 철질 카보나타이트와는 차이가 있으며 러시아 Kovdor 및 핀랜드 Sokli 지역에서 산출되는 카보나타이트의 일종인 포스코라이트(phoscorite)의 암석화학성분과 매우 유사하다.

• 자원환경지질
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• 제56권6호
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• pp.745-764
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• 2023

In the Republic of Congo, Banded iron formations (BIFs) occur in two areas: the Chaillu Massif and the Ivindo Basement Complex, which are segments of the Archean Congo craton outcropping in the northwestern and southwestern parts of the country. They show interesting potential with significant mineral resources reaching 2 Bt and grades up to 60% Fe. BIFs consist mostly of oxide-rich facies (hematite/magnetite), but carbonate-rich facies are also highlighted. They are found across the country within the similar geological sequences composed of amphibolites, gneisses and greenschists. The Post-Archean Australian Shale (PAAS)-normalized patterns of BIFs show enrichment in elements such as SiO₂, Fe₂O₃, CaO, P₂O₅, Cr, Cu, Zn, Nb, Hf, U and depletion in TiO₂, Al₂O₃, MgO, Na₂O, K₂O, Sc, Th, Ba, Zr, Rb, Ni, V. REE diagrams show slight light REEs (rare earth elements; LREEs) compared to heavy REEs (HREEs), and positive La and Eu anomalies. The lithological associations, as well as the very high (Eu/Eu^*)_SN ratios> 1.8 shown by the BIFs, suggest that they are related to Algoma-type BIFs. The positive correlations between Zr and TiO₂, Al₂O₃, Hf suggest that the contamination comes mainly from felsic rocks, while the absence of correlations between MgO and Cr, Ni argues for negligeable contributions from mafic sources. Pr/Pr^* vs. Ce/Ce^* diagram indicates that the Congolese BIFs were formed in basins with redox heterogeneity, which varies from suboxic to anoxic and from oxic to anoxic conditions. They were formed through hydrothermal vents in the seawater, with relatively low proportions of detrital inputs derived from igneous sources through continental weathering. Some Congolese BIFs show high contents in Cr, Ni and Cu, which suggest that iron (Fe) and silicon (Si) have been leached through hydrothermal processes associated with submarine volcanism. We discussed their tectonic setting and depositional environment and proposed that they were deposited in extensional back-arc basins, which also recorded hydrothermal vent fluids.