• 한국세라믹학회지
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• 제33권7호
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• pp.743-754
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• 1996

In this study (Ba1-xPbx)TiO3 was synthesized by modified oxalate process in order to prevent vaporization of PbO through low temperature synthesis climinate Cl ion reproducibly substitute Pb for by and uniformly distribute ion (Ba1-xPbx)TiO3 was synthesized by coprecipitation of lead acetate barium acetate and ammonium titanyl oxalate have been used as starting materials. The substitution of Pb for Ba was reproducibly possible synthetic temperature of perovskite structure becomes lowed as the Pb concentration increases and fine partic-les (specific surface are :7.2 cm2/g) were obtained, BaTiO3 powders calcined at 90$0^{\circ}C$ for 3 hours were cubic from in XRD analysis and as Pb content was increases evident split of tetragonal peaks could be observed The optimum conditions to synthesize (Ba,Pb)TiO3 powder are the followings ; synthesis temperature (5$^{\circ}C$)

• 대한화학회지
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• 제27권4호
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• pp.273-278
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• 1983

합성표준시료를 이용하여 주석슬랙 중 유가금속들인 $Ta_2O_5, Nb_2O_5, TiO_2, SnO_2 $및 $ZrO_2$를 X-선형광분광법으로 정량하였다. 분석시료와 표준시료분말들을 융제인 무수 $Li_2B_4O_7$과 $La_2O_3$를 무게비 15:42:3의 비율로 균일하게 혼합한다. 혼합분말을 $1,150^{\circ}C$에서 30분간 용융하여 유리구슬을 만든다. 이 구슬을 325메쉬 이하로 분쇄하여 수압기를 이용 pellet으로 만들어 시편으로 사용한다. 분석결과들은 다른 분석법에 의해 얻은 값들과 허용오차 범위내에서 잘 일치한다. 또 PTS-H시료에 대한 표준편차가 함량 3.40 %에서 0.12 %로 재현성도 좋음을 보여 주었다.

• 한국전기전자재료학회논문지
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• 제28권9호
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• pp.561-564
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• 2015

Nano-size $BaTiO_3$ powder was synthesized by relatively simple hydrothermal reaction method. Finely dispersed Ti hydroxide precursor was first precipitated using $Ti(SO_4)_2$ and NaOH solution by applying ultrasonic power and washed thoroughly to remove $SO_4{^{2-}}$ and $Na^+$ ion. Then hydrothermal reaction was done at $160^{\circ}C$ for 6 hrs using solution prepared by washed Ti hydroxide precursor slurry and $Ba(OH)_2{\cdot}8H_2O$ with Ti:Ba mole ratio of 1:1. 200 ~ 500 nm size and uniform size distributed $BaTiO_3$ powder was synthesized by relatively low temperature and simple process.

• 한국세라믹학회지
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• 제33권10호
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• pp.1138-1146
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• 1996

Al2TiO5 powder was prepared by the sol-gel processing from th metal alkoxides ; aluminium sec-butoxide (Al(OC4H9)3 and tetraethyl orthotitanate (Ti(OC2H5)4) The particles of Al2TiO5 produced from alkoxides were measured to be below $1.5mutextrm{m}$ and mre than 90% weere below 1 ${\mu}{\textrm}{m}$ however those from commercial alumina and titania were over 0.5-7${\mu}{\textrm}{m}$ and only 60% were below 1${\mu}{\textrm}{m}$ and 90% were below 2.5${\mu}{\textrm}{m}$ Therefore Al2TiO5 powder produced from alkoxides had the narrower distributionin size than that produced from the commercial alumina and titania powders. The addition of mullite or Al2O3 powder to the prepared aluminum titanate inhibited the grain growth and this resulted in decreased and increase in density.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2004년도 International Symposium on Powder Materials and Processing
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• pp.71-72
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• 2004

• 한국산학기술학회논문지
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• 제6권6호
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• pp.457-460
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• 2005

금속 알콕사이드의 가수분해법인 졸-겔 공정을 이용하여 일차로 $TiO_2$와 $ZrO_2$ 나노 입자를 합성하고 난 후 $TiO_2$ 나노입자와 PbO를 혼합하여 $PbTiO_3$의 나노 입자를 얻었다. 2차 공정으로 나노입자 크기의 $ZrO_2$와 혼합하여 최종적으로 $PbZrTiO_3(PZT)$ 분말을 합성하였다. 소결된 압전체의 결정상을 분석하기 위하여 X-선 회절분석을 시행하였으며, 소결전 합성분말의 모양과 크기를 투과전자현미경을 이용하여 관찰하였으며 $900^{\circ}C$의 저온에서 소결한 $PbZrTiO_3$시편의 미세조직을 관찰하기 위하여 주사전자현미경을 이용하였다. 합성된 입자들의 크기는 각각 $TiO_2$는 약 20 ${\~}$ 30nm, $ZrO_2$는 15${\~}$30nm이였으며, $900^{\circ}C$ 저온에서 소결한 PZT 시편의 SEM 관찰결과 평균 입경은 $2{\~}4{\mu}m$의 페로 브스카이트 결정으로 치밀한 조직을 나타내었으며, 우수한 압전 특성도 나타내었다.

• 한국세라믹학회지
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• 제31권11호
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• pp.1378-1386
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• 1994

The characteristic of calcined BaTiO3 powder and sintered PTC ceramics was investigated varing with calcination temperature and time of BaTiO(C2O4)2.4H2O synthesized from BaCl2.2H2O, TiCl4, oxalic acid and ethanol by oxalic acid method. When the particle size was less than 0.1 ${\mu}{\textrm}{m}$ by controlling calcination temperature and time, the resistance at room temperature was measured very high (above M{{{{ OMEGA }}). However, when the calcined particle sizes ranged from 0.2 to 0.3 ${\mu}{\textrm}{m}$, the resistance was 100 {{{{ OMEGA }} (After sintering, the grain size was 10~30 ${\mu}{\textrm}{m}$ homogeneously with the addition of dopant in sintering, the resistivity, resistance, $\alpha$ value and jumped to were 110{{{{ OMEGA }}.cm, 24$^{\circ}C$/% and 106{{{{ OMEGA }}, respectively.

• 마이크로전자및패키징학회지
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• 제18권2호
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• pp.57-62
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• 2011

염료 감응 태양 전지(Dye-Sensitized Solar Cells: DSSCs)의 에너지 변환효율은 $TiO_2$ 전극의 입자 크기, 구조 및 표면 형태에 의존한다. 높은 비표면적을 갖는 나노 크기의 아나타제 $TiO_2$는 많은 염료를 흡착할 수 있어 변환효율을 증가 시킨다. 또한 전극 내부에서 태양광의 산란을 증가 시키면, 염료가 태양광을 흡수하는 양이 증가하여 효율이 증가할 수 있다. 수열 합성법으로 합성한 $TiO_2$ 분말의 크기는 15-25 nm이고, 결정상은 구형의 anatase 상이다. 0.4 ${\mu}m$의 $TiO_2$ 산란입자를 합성한 나노 크기의 $TiO_2$ 분말에 혼합하여 전극을 제조하고, DSSCs를 제작한 후 변환효율을 측정하였다. 10% 의 산란 입자가 포함된 DSSCs는 단락전류 3.51 mA, 개방전압 0.79 V, 곡선인자 0.619로 6.86%의 변환 효율을 나타 내었다. 산란 입자의 영향으로 단락전류밀도는 11% 증가하였고, 효율은 0.77% 증가하였다. 산란 입자가 포함되지 않은 DSSCs 보다 산란 입자가 전극으로 들어온 태양광을 산란시켜 전자-홀 쌍의 생성을 증가 시키고, 전자가 전극을 따라 이동하는 경로가 감소하여 효율이 증가하였다. 10% 이상의 산란 입자는 전극 내부에 입자 크기의 큰 기공을 증가 시켜 효율이 감소하였다.

• 한국분말재료학회지
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• 제26권5호
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• pp.405-409
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• 2019

Piezoelectric ceramic specimens with the $Pb(Mg_{1/3}Nb_{2/3})_{0.65}Ti_{0.35}O_3$ (PMN-PT) composition are prepared by the solid state reaction method known as the "columbite precursor" method. Moreover, the effects of the $Li_2O-Bi_2O_3$ additive on the microstructure, crystal structure, and piezoelectric properties of sintered PMN-PT ceramic samples are investigated. The addition of $Li_2O-Bi_2O_3$ lowers the sintering temperature from $1,200^{\circ}C$ to $950^{\circ}C$. Moreover, with the addition of >5 wt.% additive, the crystal structure changes from tetragonal to rhombohedral. Notably, the sample with 3 wt.% additive exhibits excellent piezoelectric properties ($d_{33}=596pC/N$ and Kp = 57%) and a sintered density of $7.92g/cm^3$ after sintering at $950^{\circ}C$. In addition, the sample exhibits a curie temperature of $138.6^{\circ}C$ at 1 kHz. Finally, the compatibility of the sample with a Cu electrode is examined, because the energy-dispersive X-ray spectroscopy data indicate the absence of interdiffusion between Cu and the ceramic material.

• 한국분말재료학회지
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• 제25권1호
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• pp.1-6
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• 2018

Uniform $TiO_2$ blocking layers (BLs) are fabricated using ultrasonic spray pyrolysis deposition (USPD) method. To improve the photovoltaic performance of dye-sensitized solar cells (DSSCs), the BL thickness is controlled by using USPD times of 0, 20, 60, and 100 min, creating $TiO_2$ BLs of 0, 40, 70, and 100 nm, respectively, in average thickness on fluorine-doped tin oxide (FTO) glass. Compared to the other samples, the DSSC containing the uniform $TiO_2$ BL of 70 nm in thickness shows a superior power conversion efficiency of $7.58{\pm}0.20%$ because of the suppression of electron recombination by the effect of the optimized thickness. The performance improvement is mainly attributed to the increased open-circuit voltage ($0.77{\pm}0.02V$) achieved by the increased Fermi energy levels of the working electrodes and the improved short-circuit current density ($15.67{\pm}0.43mA/cm^2$) by efficient electron transfer pathways. Therefore, optimized $TiO_2$ BLs fabricated by USPD may allow performance improvements in DSSCs.