• 한국전기전자재료학회논문지
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• 제37권2호
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• pp.202-207
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• 2024

This study examines a manufacturing process for the photoelectrode material of dye-sensitized solar cell (DSSC) intending to increase efficiency through the surface plasmon resonance phenomenon of nanoparticles with a composite structure made of Ag and TiO₂. This invention involves the use of Ag and TiO₂ nanoparticles in the solar cell. These nanoparticles cause surface plasmon resonance, which amplifies and scatters incident solar energy, enhancing the dye's rate of light absorption. It also makes it possible to absorb energy in wavelength ranges that were previously difficult to do, which increases efficiency. Centrifugal separation and heat synthesis are used to create the composite metal structures, and certain combinations are used to decide the particle morphologies. To increase the efficiency of organic solar cells and DSSC, the Ag/TiO₂ composite structure is therefore quite likely to be used.

• 한국진공학회지
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• 제17권4호
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• pp.317-321
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• 2008

세라믹 강유전체 $0.65Pb(Mg_{1/3}Ta_{2/3})O_3-0.35PbTiO_3$ 고용체에 $ZrO_2$를 첨가하여 유전 및 초전 특성을 관찰하였다. 유전상수, 유전손실 및 초전계수의 측정온도는 상온에서 $250^{\circ}C$사이에서 측정되었다. 유전상수와 초전계수는 $0.2\;mol%ZrO_2$ 첨가에서 최대값을 얻었다. $ZrO_2$의 첨가량이 증가할수록 각 시료의 유전상수와 초전계수의 최대값은 낮은 온도로 이동하였고, 최대유전상수의 퍼짐현상은 증가하였다.

• 한국전기전자재료학회논문지
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• 제35권1호
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• pp.24-31
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• 2022

This study investigated microstructures, crystal structures, polarization, dielectric and electromechanical properties of 0.76Bi_1/2Na_1/2TiO₃-0.24SrTiO₃ (BNT-24ST)-based piezoceramcs by adding Li₂CO₃ and B₂O₃ (LB) as sintering aids for low-temperature sintering. All samples were successfully synthesized using conventional solid-state reaction method and sintered at 950, 1,000, 1,050, 1,100 and 1,175℃ for 2 hours. Without LB, specimens required sintering temperatures over 1,175℃ for sufficient densification, while the addition of 0.10-mol LB decreased the sintering temperatures down to 950℃. The average grain size and dielectric properties of BNT-24ST-10LB ceramics were enhanced with increasing sintering temperature. We found that the low-temperature sintered BNT-24ST piezoceramics by adding LB showed the d₃₃*value of 402 pm/V at 4 kV/mm after sintering at 1,050℃, which was better than that of high-temperature fired specimens sintered at 1,175℃ without LB (242 pm/V). We believe that the results of this study promise a candidate for low-cost multilayer ceramic actuator applications.

• 공업화학
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• 제7권6호
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• pp.1192-1203
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• 1996

알루미늄 및 티타늄 알콕사이드의 가수분해방법을 인용하여 고온수중에 적용할 수 있는 $Al_2O_3-TiO_2$ 복합옥사이드형 흡착제를 제조하였다. 제조한 흡착제는 $600{\sim}1400^{\circ}C$의 온도로 하소되었으며, 결정전이, 열적 특성, 비표면적 등의 물성변화를 알아 보기 위하여 X선회절, 적외선분광분석, 열분석 전자현미경 관찰, BET 방법에 의한 측정 등을 수행하였다. 그리고 Autoclave를 이용한 회분식 흡착실험으로 이 흡착제들의 $TiO_2$ 함량 및 하소 온도 변화에 따르는 고온수중에서의 $Co^{2+}$ 흡착 특성을 알아 보았다. $150{\sim}250^{\circ}C$의 온도 범위에서 $Al_2O_3-TiO_2$ 흡착제의 $Co^{2+}$ 흡착반응에 대한 표준 엔탈피 변화값은 $TiO_2$ 함량이 26mol%, 43mol%, 80mol%에 대하여 $16.5{\sim}26.0kJ{\cdot}mol^{-1}$범위에 있었으며, 이 흡착반응이 비가역적인 흡열반응임을 알 수 있었다. $250^{\circ}C$의 고온수에서 하소 온도가 $600^{\circ}C$, $TiO_2$함량이 26mol%인 흡착제의 코발트 평형흡착용량은 $0.1674meq{\cdot}g^{-1}$이었다.

• 한국전기전자재료학회논문지
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• 제35권1호
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• pp.93-97
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• 2022

We report highly efficient quantum dot light-emitting diodes (QLEDs) with TiO₂ nanoparticles (NPs) as an alternative electron transport layer (ETL) and poly (methyl methacrylate) (PMMA) as an insulating layer. TiO₂ NPs were applied as ETLs of inverted structured QLEDs and the effect of the addition of PMMA between ETL and emission layer (EML) on device characteristics was studied in detail. A thin PMMA layer supported to make the charge balance in the EML of QLEDs due to its insulating property, which limits electron injection effectively. Green QLEDs with a PMMA layer produced the maximum luminance of 112,488 cd/m² and a current efficiency of 25.92 cd/A. We expect the extended application of TiO₂ NPs as the electron transport layer in inverted structured QLEDs device in the near future.

• 한국재료학회지
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• 제12권12호
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• pp.947-954
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• 2002

HCl concentration and reaction time are the decisive factors in determining the structure of precipitates in the process of synthesis of $TiO_2$ particles from aqueous $TiOCl_2$ solution by precipitation and the volumetric proportion of brookite phase in $TiO_2$ particles can be controlled by these two factors. As reaction rate increases with increase of reaction temperature, the reaction time, at which maximum volumetric proportion of brookite phase in $TiO_2$ particles was obtained, was reduced. The brookite was transformed directly to rutile phase with only increase of reaction time. And precipitation was delayed with increase of HCl concentration because the amount of $H_2$O, which is necessary source of oxygen for conversion of $Ti^{+4}$ to $TiO_2$, was relatively reduced with increase of that. Brookite in the mixture phase powder was finally transformed to rutile phase via anatase through heat-treatment.

• 한국세라믹학회지
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• 제45권4호
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• pp.220-225
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• 2008

Lead-free ferroelectric ceramics are widely researched today for industrial applications as sensors, actuators and transducers. Since $Pb(Zr_aTi_{1-a})O_3$-(PZT) has high Curie temperature($T_C$), high piezoelectric properties near its morphotropic phase boundary(MPB) composition and small temperature dependence electrical behavior, it has been used to commercial materials for wide temperature range and different application fields. According to the tolerance factor concept, since the $Bi^{3+}$ cation with 12-fold coordinate has a smaller ionic radius than 12-fold coordinate $Pb^{2+}$, most bismuth based perovskites possess a smaller tolerance factor. Therefore, MPBs with a higher $T_C$ may be expected in $Bi(Me^{3+})O_3PbTiO_3$ solid solutions. As in lead based perovskite systems, it is clear that we need to explore more materials in simple or complex bismuth based MPB systems. The objective of this study is to investigate the $Bi(Ni_{1_a}X_a)O_3-PbTiO_3(X=Ti^{4+},\;Nb^{5+})$ perovskite solid-solution. For improving the electronic conduction problem, the magnesium and manganese modified system was also studied.

• 한국전기전자재료학회논문지
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• 제16권7호
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• pp.599-603
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• 2003

Ferroelectric B $i_4$$_{-x}$N $d_{x}$ $Ti_3$ $O_{12}$ (BNdT) thin films with the composition(x=0.75) were prepared on Pt/Ti/ $SiO_2$(100) substrate by metal-organic deposition. The films were annealed by various temperatures from 550 to $650^{\circ}C$ and then the electrical and structural characteristics of BNdT films were investigated for the application of FRAM. Electrical properties such as dielectric constant, 2Pr and capacitance were quite dependent on the thermal heat treatment. The measured 2Pr value on the BNdT capacitor annealed at $650^{\circ}C$ was 56$\mu$C/$\textrm{cm}^2$ at an applied voltage of 5V. In fatigue characteristics value remained constant up to 8$\times$10$^{10}$ read/write switching cycles at a frequency of 1Mhz regardless of annealing temperatures.

• 한국결정성장학회지
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• 제21권5호
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• pp.214-217
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• 2011

Fresnoite 결정화 유리는 최근 비선형 광학특성으로 인하여 널리 연구되어 지고 있다. 그러나, 이전 연구 결과를 통하여 투명결정화 유리의 화학 조성으로는 정량적으로 Fresnoite 구조에 유사한 조성을 조절하는 것에 한계가 있음을 확인 할 수 있다. 본 연구에서는 $K_2O-TiO_2-SiO_2$ glass의 제조한 후, 제조된 유리를 $Sr(NO_3)_2$ 용융염에 담지하여 모유리의 표면에 Fresnoite 결정을 형성시키는 방법으로 투명결정화 유리를 제조하고, 이 때 Sr 이온이 비선형광학효과에 미치는 영향을 살펴보았다. XRD를 통하여 담지 시간에 따른 결정상 변화와 열처리를 통한 결정상 변화를 관찰하였으며, FE-SEM을 사용하여 생성된 결정의 미세구조와 Nd : YAG laser를 사용하여 2차비선형특성의 유무를 관찰하였다.

• 한국전기전자재료학회논문지
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• 제29권6호
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• pp.342-347
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• 2016

We investigated the effect of $Bi_{1/2}(Na_{0.82}K_{0.18})_{1/2}TiO_3$ (BNKT) modification on the ferroelectric and electric-field-induced strain (EFIS) properties of lead-free $0.97Bi_{1/2}(Na_{0.82}K_{0.18})_{1/2}TiO_3-0.03LaFeO_3$ (BNKTLF) ceramics as a function of BNKT content (x= 0, 0.1, 0.2, 0.3, 0.5, and 1). BNKT-modified BNKTLF powders were synthesized using a conventional solid-state reaction method. As the BNKT content x increased from 0 to 1 the normalized electric-field-induced strain ($S_{max}/E_{max}$) was observed to increase at relatively low fields, i.e., below the poling field. Moreover, BNKTLF-30BNKT showed about 460 pm/V as low as at 3 kV/mm, which is a considerably high value among the lead-free systems reported so far. Consequently, it was confirmed that ceramic-ceramic composite, a mixture of an ergodic relaxor matrix and embedded ferroelectric seeds, is a salient way to make lead-free piezoelectrics practical with enhanced EFIS at low field as well as less hysterical.