• 한국자기학회지
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• 제16권5호
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• pp.245-248
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• 2006

Sol-gel법을 이용하여 단일상을 갖는 $Tb_{3-x}Bi_xFe_5O_{12}$ 분말 시료를 제조하였으며, 그 결정학적 및 자기적 특성을 x-선 회절법(XRD), 진동 시료 자화율 측정법(VSM), $M\"{o}ssbauer$ 분광법으로 연구하였다. XRD 분석 결과 결정구조는 Ia3d의 공간그룹을 갖는 cubic 구조임을 알 수 있었고, Bismuth의 치환량이 x=0.5, 0.75, 1.0 및 1.25로 증가할수록 격자상수가 각각 $a_0=12.466{\AA},\;12.487{\AA},\;12.499{\AA},\;12.518{\AA}$으로 선형적으로 증가함을 확인할 수 있었다. VSM을 이용한 온도에 따른 자기모멘트 측정 결과 Bismuth의 치환량이 증가하면 $N\'{e}el$ 온도는 증가하며 compensation 온도는 감소함을 확인할 수 있었다. 또한 field cooled 조건에서 비정상적인 음의 자화값이 관측되었다. $M\"{o}ssbauer$ 스펙트럼은 4.2 K에서부터 $N\'{e}el$ 온도까지 측정하였으며, 분석 결과 상온에서 모든 시료의 이성질체 이동치의 값은 평균적으로 0.27mm/s로 철의 이온상태가 +3가 임을 확인할 수 있었다.

• 전기화학회지
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• 제12권4호
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• pp.335-341
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• 2009

Organic-inorganic hybrid sol-gel matrices were used as hosts for chloro (5, 10, 15, 20-tetraphenylporphyrinato) cobalt (III) (Co[TPP]Cl), a known ionophore for nitrite. The sol-gel precursor was prepared by the reaction of (3-isocyanopropyl) triethoxysilane with 1,4-butanediol. An appropriate amount of the anion-exchanger, tridodecylmethylammonium chloride (TDMAC) and the plasticizer, tributylphosphate (DBP) were used as membrane additives. On mixing with an acidic catalyst, the sol-state precursors slowly gelled, yielding a membrane in which the active components, Co[TPP]Cl and TDMAC, were encapsulated. The performances of the sol-gel membrane-based electrodes were compared to those of Co[TPP]Cl-based poly(vinyl chloride) (PVC) membrane electrodes. Membranes with a molar ratio of Co[TPP]Cl: TDMAC (1 : 0.1) showed reasonable response slopes toward nitrite. The response slopes were typically 53 mV/decade between $10^{-5.4}$ and $10^{-1.0}\;M$. Selectivities toward nitrite over hydrophilic and small anions such as chloride were somewhat inferior to those observed with PVC-based membranes, but selectivities over lipophilic anions were quite similar. Reduced asymmetry potentials due to protein adsorption were found to occur with the sol-gel matrix relative to PVC-based films when the sensors were employed as a detector in flow-through configuration.

• 한국세라믹학회지
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• 제36권4호
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• pp.391-402
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• 1999

Characteristics of composite electrolytes which were prepared by coating a thin film of YSZ (yttria sta-bilized zirconia : (ZrO2)0.92 (Y2O3)0.08) on YDC (yttria doped ceria : Ce0.8Y0.2O1.9) with mixed conductivity have been investigated in order to develop the low-temperature solid oxide fuel cell. The thickness (t) of spin-coated YSZ thin films after the heat-treatment at 600$^{\circ}C$ was increased proportionally to the sol con-centrations (C) while the decrease in its thickness with the spin rate ($\omega$) could be expressed in the e-quation of ln t=9.49-0.53 ln $\omega$(0.99mol//s sol conc.) When the sol concentration and the spin rate being less than 0.99 mol/l and higher than 1000 rpm respectively reliable YSZ/YDC composite electrolytes could be obtained by multi-coating although several micro-cracks were observed in singly coated YSZ film surfaces. The dense YSZ film with a 1$\mu\textrm{m}$ thickness was prepared by coating of 0.99 mol/l YSZ sol five-times at 2000 rpm followed by heat-treatment at 1400$^{\circ}C$ for 2h, The adhesion between YSZ film and YDC substrate was found to be very good. The open circuit voltages of H2/O2 single cell with YSZ/YDC composite electrolytes were 0.79∼0.82 V at 800$^{\circ}C$ and 0.75∼0.77V at 900$^{\circ}C$ The open circuit voltage was inversely proportioned to the thickness ratio of YSZ thin film (1$\mu\textrm{m}$) to YDC substrate(0.28-2.22 mm)

• 한국자기학회지
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• 제13권6호
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• pp.231-236
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• 2003

Co-페라이트 CoF $e_2$ $O_4$에서 Fe 이온의 소량을 Al 이온으로 치환시킨 시료인 $A_{10.2}$ CoF $e_{1.8}$ $O_4$을 sol-gel 방법으로 제조하여 열처리 온도에 따른 결정학적 및 자기적 특성의 변화를 밝히기 위하여 x-선 회절기, FE-SEM, Mossbauer 분광기, 진동자력계 등을 이용한 측정을 하였다. 결정 구조는 spinel임을 알 수 있었으며, 격자 상수 값은 열처리 온도가 증가함에 따라 837 K 때 8.425 $\AA$에서 1073 K 때 8.321 $\AA$으로 감소하였다. 입자크기는 열처리 온도가 증가함에 따라 673 K 때 약 39 nm에서 1073 K 때 약 108 nm로 크게 증가하였다. 873 K 이상에서 열처리한 시료의 Mossbauer spectrum은 상온에서 F $e^{3+}$ 가 A와 B자리에 위치하여 나타나는 한 세트의 육중선이 중첩된 모양이었는데, 열처리 온도 증가에 따라 A자리의 초미세 자기장 값은 서서히 증가하였으나 B자리의 값은 빠르게 증가하였다. 이성질체 이동값과 사중극자 분열값은 거의 일정하였다. 포화자화는 473 K 때 0.7 emu/g 1073 K 때 72.1 emu/g로 선형적으로 급격히 증가하고, 보자력은 673 K 때 0.951 tOe에서 1073 K 때 0.374 tOe로 급격히 감소하였다.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2003년도 춘계종합학술대회
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• pp.374-377
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• 2003

Sol-gel processing of BaTiO$_3$ ceramics doped with La(0.01-1.00 at.%) were prepared from metal barium, titanium n-butoxide and lanthanum isopropoxide. Characterization of the sol-gel-derived powder using XRD, SEM is also reported. The obtained results suggested that insulator to semiconductor transition for highly donor-doped barium titanate was closely related to the incorporation of donor into the grains and to the resultant grain size, which were significantly affected by the sinterability of BaTiO$_3$ powders and sintering conditions used.

• The Korean Journal of Ceramics
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• 제1권3호
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• pp.160-164
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• 1995

Mechanical and chemical tests were performed on $Zro_2 \cdot SiO_2$ glass fibers manufactured by the sol-gel method and E-glass fibers-reinforced cement composites in order to investigate the interactions between glass fibers and cement matrices. Chemical attack leads to corrosion of the glass fiber surfaces. In the corrosion reactions, the surface of $30ZrO_2 \cdot 70 SiO_2$ glass fibers developed a densified concentric layer, which consists of glass corrosion products with much higher Zr and lower Si than the fresh glass fiber. The layer of reaction product is regarded to stiffen the cement matrices and provide a useful improvement to the mechanical properties. The addition of $ZrO_2$ content increases the corrosion resistance of glass fibers in cement by forming a passivating layer on the surface of glass fibers.

• E2M - 전기 전자와 첨단 소재
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• 제7권2호
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• pp.152-156
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• 1994

The rapid thermal annealing effects of Sol-Gel derived ferroelectric PZT thin films were investigated. It was found that rapid thermal annealing(RTA) of spin coated thin films on silicon typically >$800^{\circ}C$ for about 1 min. was changed to the perovskite phase. Rapid thermally annealed films recorded maximum remanent polarization of about 5 .mu.C/cm$^{2}$, coercive field of around 30kV/cm. The switching time for polarization reversal was about 220ns. The films of RTA process showed smooth surface, and high breakdown voltages of over 1 MV/cm and resistivity of $1{\times}{10^12}$ .ohm.cm at 1 MV/cm. It was verified that the polarization reversal of the PZT film was varied partially with applying the multiple short pulse.

• Journal of Electrical Engineering and Technology
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• 제8권1호
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• pp.163-167
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• 2013

Aluminum doped zinc oxide (AZO) thin films have been prepared on the glass substrates (Corning 1737) by sol-gel dip-coating method employing zinc acetate and aluminum chloride hexahydrate for the transparent conducting oxide (TCO) applications. 1 at% Al was doped to the ZnO thin films. The effects of post-heating temperature on the crystallization, optical and electrical properties of the AZO films have been investigated. Experimental results showed that post-heating temperature affected the microstructure, electrical resistance, and optical transmittance of the AZO films. From the X-ray diffraction analysis, all films have hexagonal wurtzite crystal structure. Optical transmittance spectra of the AZO films exhibited transmittance higher than about 80% within the visible wavelength region and the optical direct band gap ($E_g$) of these films was increased with increasing post-heating temperature. A minimum resistivity of $2.5{\times}10^{-3}{\Omega}cm$ was observed at $650^{\circ}C$.

• Transactions on Electrical and Electronic Materials
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• 제2권2호
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• pp.32-36
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• 2001

A new solid source for low temperature diffusion into silicon was developed. The source wafer consists of an “active” compound, which is sol-gel prepared phosphosilicate glass-ceramics containing 56% P$_2$O$\sub$5/, embedded in a skeletal foam-like, inert substrate. Phosphorus diffusion from the new solid sources at low temperatures (800-875$^{\circ}C$) produced reprodecible sheet resistances and shallow junctions. From a series of one hour doping runs, the life time of the phosphosilicate source was determined to be over 40 hours. The effective diffusion coefficient of phosphorus into silicon and the corresponding activation energy at 850$^{\circ}C$ were determined to be 7.5${\times}$10$\^$-15/ $\textrm{cm}^2$/sec and ∼3.9 eV, respectively.

• 한국광학회:학술대회논문집
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• 한국광학회 2001년도 제12회 정기총회 및 01년도 동계학술발표회
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• pp.266-267
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• 2001

TiO$_2$와 SiO$_2$는 일반적으로 가시광 영역에서부터 근적외선까지의 넓은 파장영역의 광학박막을 제작하기 위한 물질로서 사용되어져 오고 있다. 이 두 물질은 비교적 큰 굴절률 차이를 지니고 있어 이들을 이용한 다층박막 또는 혼합박막에 대한 연구가 이루어져왔다. TiO$_2$-SiO$_2$ 혼합박막을 제작하기 위해 e-beam evaporation, CVD, flame hydrolysis, sol-gel 등 다양한 방법이 연구되고 있다. 특히 sol-gel법은 혼합물질의 조성이 용이하고 최종 물질의 광학적 특성이 우수하다. (중략)