• Title/Summary/Keyword: %24TiO_2%24

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Cation Ordering and Microwave Dielectric Properties of Complex Perovskite Compounds $La(Mg_{1/2}Ti_{1/2})O_3$ and $La(Mg_{1/2}Zr){1/2})O_3$ ($La(Mg_{1/2}Ti_{1/2})O_3$$La(Mg_{1/2}Zr){1/2})O_3$에서의 양이온 규칙과 고주파 유전특성)

  • 조서용;고경현;홍국선;박순자
    • Journal of the Korean Ceramic Society
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    • v.34 no.3
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    • pp.330-336
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    • 1997
  • 1:1 복합 페로스카이트 물질인 La(Mg1/2Ti1/2)O3 and La(Mg1/2Zr1/2)O3의 양이온 규칙 존재와 고주파 유전특성을 x선 회절과 회로망분석기를 사용하여 조사하였다. 기존의 연구에서는 두 물질 모두 양이온 규칙이 없으며 입방정 구조를 갖는다고 보고되었지만, 본 연구에서의 x선 분석에서는 양이온 규칙을 나타내는 초격자회절선과 비입방정 구조를 의미하는 기본회절선의 split이 발견되었다. 고주파 영역에서의 유전율은 La(Mg1/2Ti1/2)O3의 경우 29,La(Mg1/2Zr1/2)O3는 24, 품질계수(Q*f)는 각각 73000, 49000이다. 공진주파수 온도계수는 La(Mg1/2Ti1/2)O3의 경우 - 65ppm/$^{\circ}$C,La(Mg1/2Zr1/2)O3는 -80ppm/$^{\circ}$C로 음의 값을 가진다.

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Fabrication of Electrochemical method (전기화학 합성)

  • Lee, Sang-Heon;Choi, Yong
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2010.06a
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    • pp.284-284
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    • 2010
  • YBCO ceramic specimens were fabricated by added $BaTiO_3$ as donors and sintered $950^{\circ}C$/24hrs. Average grain size decreased with increased in added $BaTiO_3$. Affect to grain growth. XRD result, peak strength was lowed then crystallization not well all specimens. All specimens critical temperature about 90k.

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The effects of UV excited $TiO_{2}$ and ZnO coating on activated carbon for Escherichia coli (활성탄에 침착시킨 $TiO_2$와 ZnO가 자외선에 의하여 활성화되었을때 Escherichia coli의 살균효과에 미치는 영향에 관한 연구)

  • 최명신;정문호;김영규
    • Journal of environmental and Sanitary engineering
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    • v.10 no.3
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    • pp.105-114
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    • 1995
  • There has been increasing awareness on the importance of not only removal of organic materials but also sterilization of microbial cell in the drinking water purification research, so there has been many researches on that area. This study has been designed to analyze the effects of $TiO_{2}$ and ZnO coated on activated carbon on Escherichia coli. In this study, the sterilization power was analyzed by (1) variation of $TiO_{2}$ and ZnO concentration coated on activated carbon (2) variation of UV intensity. In addition, the kinetics between exposure time and sterilization velocity was viewed by the method of Chick. The results are as follows. 1. Survival ratio of E. coli decreased as time goes on in application of $TiO_{2}$, ZnO and $TiO_{2}{\cdot}ZnO$. In $TiO_{2}$ and ZnO, the effect increased upto certain concentration, but decreased there-after. In $TiO_{2}{\cdot}ZnO$, the effect of sterilization was in similar way among 3 combinations. 2. Survival ratio of E. coli decreased proportionately to an increase of light intensity in ZnO and $TiO_{2}{\cdit}ZnO$. In $TiO_{2}$, the survival ratio differed over extent of irradiation but the difference over the light intensity was not significant. 3. When Chick's law of sterilization was applied, m values of three concentrations of $TiO_{2}$ were 1.57,0.98, 1.96 respectively. M values of three concentration of ZnO were 1.10, 1.18,0. 11 respectively and those of three combination of $TiO_{2}{\cdot}ZnO$ were 1.17, 1.24, 1.74 respectively.

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Effects of $B_2O_3$ Addition on the Sintering Behavior and the Microwave Dielectric Properties of $(Mg_{0.93}Ca_{0.07})TiO_3$ Ceramics ($(Mg_{0.93}Ca_{0.07})TiO_3$ 세라믹스의 소결 및 마이크로파 유전특성에 미치는 $B_2O_3$의 영향)

  • 이득우;박재환;김인태;박재관;김윤호;최덕균
    • Journal of the Korean Ceramic Society
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    • v.35 no.3
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    • pp.287-293
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    • 1998
  • The effects of B2O3 addition on the sintering behavior and th microwave dielectric properties of $(Mg_{0.93}Ca_{0.07})TiO_3$ ceramics were investigated. By addition of $B_2O_3$, increases the density of the ceramics increases and grain growth enhances, It was densified to over 94% of $(Mg_{0.93}Ca_{0.07})TiO_3$ theoretical density by the addition of 0.15-1.0wt% B2O3 and stable microwave dielectric properties observed by the addition of 0.2-0.4wt% $B_2O_3.\;(Mg_{0.93}Ca_{0.07})TiO_3$ ceramics sintered at $1200^{\circ}C$ exhibits maximum dielectric constants of 24-25 quality factor($Q{\times}f$) of more than 70000 and temperature coefficient of resonant frequency of $0\;ppm/^{\circ}C$ by adding of 0.15-0.4wt% $B_2O_3$.

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Influence of Ag Thickness on the Properties of TiO2/Ag/TiO2 Trilayer Films (Ag 중간층 두께에 따른 TiO2/Ag/TiO2 박막의 광학적 특성 변화)

  • Kim, So-Young;Jeon, Jae-Hyun;Gong, Tae-Kyung;Kim, Sun-Kyung;Choi, Dong-Hyuk;Son, Dong-Il;Kim, Daeil
    • Journal of the Korean Society for Heat Treatment
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    • v.28 no.2
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    • pp.63-67
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    • 2015
  • $TiO_2/Ag/TiO_2$ trilayer films were deposited with radio frequency (RF) and direct current (DC) magnetron sputtering onto the glass substrate to consider the influence of Ag interlayer on the optical properties of the films. The thickness of $TiO_2$ films was kept at 24 nm, while the thickness of Ag interlayer was varied as 5, 10, 15, and 20 nm. As-deposited $TiO_2$ single layer films show the optical transmittance of 66.7% in the visible wave-length region and the optical reflectance of 16.5%, while the $TiO_2$ films with a 15 nm thick Ag interlayer show the enhanced optical transmittance of 80.2% and optical reflectance of 77.8%. The carrier concentration was also influenced by Ag interlayer. The highest carrier concentration of $1.01{\times}10^{23}cm^{-3}$ was observed for a 15 nm thick Ag interlayer in $TiO_2/Ag/TiO_2$ films. The observed result means that an optimized Ag interlayer in $TiO_2/Ag/TiO_2$ films enhanced the structural and optical properties of the films.

Effect of calcination temperature on the Coloring of $TiO_2-WO_3$-NiO Pigments ($TiO_2-WO_3$-NiO 안료의 발색특성에 대한 소결온도의 영향)

  • Chun, Myuong-Pyo;Kang, Kyung-Min;Cho, Jeong-Ho;Kim, Byung-Ik;Kwon, Myon-Joo
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2010.06a
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    • pp.274-274
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    • 2010
  • 안료의 색상은 출발원료의 조성, 입자크기 및 소결온도에 의한 결정구조 등에 의존한다. 본 연구에서는 Rutile구조를 갖는 세라믹안료인 $TiO_2-WO_3$-NiO의 합성에서 소결온도를 결정하기 위해 소결전 출발원료를 습식법에 의하여 Jar Mill에서 0.7-0.9um로 혼합분쇄한 후 $100^{\circ}C$에서 24시간 건조하였다. 건조후 $1100-1280^{\circ}C$에서 5구간을 선정하여 소결한 시료를 Jar Mill에서 0.8-1um로 분쇄한 후, 다시 $100^{\circ}C$에서 24시간 건조하였다. 이렇게 얻어진 시료를 XRD로 상합성 정도를 조사하고, 색상 및 착색력을 spectrophotometer를 분석하였다. 색상은 1150와 $1250^{\circ}C$에서 가장 좋은 Yellow 색상이 관찰되었으며, XRD에 의한 결정성의 분석결과와 비교적 일치하고 있다. Rutile구조를 갖는 세라믹안료의 색상은 소결시의 결정화도에 따라 민감하게 변화되고 있음을 알 수 있다.

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Evaluation of OH Radical Generation to Nanotube Morphology of TiO2 Nanotube Plate (TiO2 nanotube plate의 nanotube 형태에 따른 OH radical 생성량 평가)

  • Lee, Yongho;Pak, Daewon
    • Journal of Korean Society on Water Environment
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    • v.32 no.5
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    • pp.403-409
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    • 2016
  • In this study, a TiO2 nanotube was grown on a titanium plate by using anodic oxidation method for the evaluation of TiO2 nanotube morphology. The TiO2 nanotube was grown in an electrolyte containing ethylene glycol, 0.2 wt% of NH4F and 2 vol% of H2O. Applied voltage varied from 30 to 70 V and the morphology of the TiO2 nanotube was observed. After anodization, a TiO2 nanotube plate was immersed in 35℃ ethanol for 24 hours. Anatase and rutile crystal forms of TiO2 nanoutbe were observed after annealing. 4-chrolobenzoic acid, a probe compound for OH radicals, was dissolved in H2O in order to measure the OH radical. Liquid chromatography was used to check the concentration of the 4-chrolobenzoic acid. The OH radical generation by TiO2 nanotube plate was proportionate to the length of the TiO2 nanotube. Furthermore, when the number of TiO2 nanotube plate increased, the OH radical generation increased as well.

Characteristics of Disc-Type V2O5 Catalyst Impregnated Ceramic Filters for NOx Removal (질소산화물 제거를 위한 디스크형 바나디아 촉매담지 세라믹필터의 특성)

  • 홍민선;문수호;이재춘;이동섭
    • Journal of Korean Society for Atmospheric Environment
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    • v.20 no.4
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    • pp.451-463
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    • 2004
  • The performance of disk-type catalytic filters impregnated by TiO$_2$ or TiO$_2$-3Al$_2$O$_3$ㆍ 2SiO$_2$ supports and V$_2$O$_{5}$ catalyst was evaluated for selective catalytic reduction (SCR) of NO with ammonia as a reductant. XRD, FT -IR, BET and SEM were used to characterize the catalytic filters prepared in this work. Optimal V$_2$O$_{5}$ loading and reaction temperature for V$_2$O$_{5}$/TiO$_2$ catalytic filters were 3-6 wt.% and 350-40$0^{\circ}C$ at GHSV 14,300 $hr^{-1}$ in the presence of oxygen, respectively. With increasing the V$_2$O$_{5}$ loading from 0.5 to 6 wt%, NO conversion increased from 24 to 96% at 40$0^{\circ}C$ and 14.300$hr^{-1}$, and maintained at 80% over in the V$_2$O$_{5}$ loading range of 3-6 wt.% and then dropped at V$_2$O$_{5}$ loading of 7wt.% over. In comparing V$_2$O$_{5}$/ TiO$_2$ and V$_2$O$_{5}$/ TiO$_2$-3Al$_2$O$_3$ㆍ2SiO$_2$ catalytic fillers, which have same 3wt.% V$_2$O$_{5}$ loading, the V$_2$O$_{5}$/ TiO$_2$-3A1$_2$O$_3$ㆍ2SiO$_2$ catalytic filter showed higher activity than V$_2$O$_{5}$/ TiO$_2$ catalytic filter, but higher differential pressure drops owing to its low air permeability. low air permeability.

Two Anhydrous Zeolite X Crystal Structures, $Pd_{18}Ti_{56}Si_{100}Al_{92}O_{384} and Pd_{21}Tl_{50}Si_{100}Al_{92}O_{384}$

  • Yun, Bo Yeong;Song, Mi Gyeong;Lee, Seok Hui;Kim, Yang
    • Bulletin of the Korean Chemical Society
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    • v.22 no.1
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    • pp.30-36
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    • 2001
  • The crystal structures of fully dehydrated $Pd^{2+}$ - and $TI^{+}$ -exchanged zeolite X, $Pd_{18}TI_{56}Si_{100}Al_{92}O_{384}(Pd_{18}TI_{50-}X$, a = $24.935(4)\AA$ and $Pd_{21}TI_{50}Si_{100}Al_{92}O_{384}(Pd_{21}TI_{50-}X$ a = $24.914(4)\AA)$, have been determined by single-crystal X-ray diffraction methods in the cubic space group Fd3 at $21(1)^{\circ}C.$ The crystals were prepared using an exchange solution that had a $Pd(NH_3)_4Cl_2\;:TINO_3$ mole ratio of 50 : 1 and 200 : 1, respectively, with a total concentration of 0.05M for 4 days. After dehydration at $360^{\circ}C$ and 2 ${\times}$$10^{-6}$ Torr in flowing oxygen for 2 days, the crystals were evacuated at $21(1)^{\circ}C$ for 2 hours. They were refined to the final error indices $R_1$ = 0.045 and $R_2$ = 0.038 with 344 reflections for $Pd_{18}Tl_{56-}X$, and $R_1$ = 0.043 and $R_2$ = 0.045 with 280 reflections for $Pd_{21}Tl_{50-}X$; I > $3\sigma(I).$ In the structure of dehydrated $Pd_{18}Tl_{56-}X$, eighteen $Pd^{2+}$ ions and fourteen $TI^{+}$ ions are located at site I'. About twenty-seven $TI^{+}$ ions occupy site II recessed $1.74\AA$ into a supercage from the plane of three oxygens. The remaining fifteen $TI^{+}$ ions are distributed over two non-equivalent III' sites, with occupancies of 11 and 4, respectively. In the structure of $Pd_{21}Tl_{50-}X$, twenty $Pd^{2+}$ and ten $TI^{+}$ ions occupy site I', and one $Pd^{2+}$ ion is at site I. About twenty-three $TI^{+}$ ions occupy site II, and the remaining seventeen $TI^{+}$ ions are distributed over two different III' sites. $Pd^{2+}$ ions show a limit of exchange (ca. 39% and 46%), though their concentration of exchange was much higher than that of $TI^{+}$ ions. $Pd^{2+}$ ions tend to occupy site I', where they fit the double six-ring plane as nearly ideal trigonal planar. $TI^{+}$ ions fill the remaining I' sites, then occupy site II and two different III' sites. The two crystal structures show that approximately two and one-half I' sites per sodalite cage may be occupied by $Pd^{2+}$ ions. The remaining I' sites are occupied by $TI^{+}$ ions with Tl-O bond distance that is shorter than the sum of their ionic radii. The electrostatic repulsion between two large $TI^{+}$ ions and between $TI^{+}$ and $Pd^{2+}$ ions in the same $\beta-cage$ pushes each other to the charged six-ring planes. It causes the Tl-O bond to have some covalent character. However, $TI^{+}$ ions at site II form ionic bonds with three oxygens because the super-cage has the available space to obtain the reliable ionic bonds.

The Microstructure and Electrical Properties in the Pb(Sb1/2 Nb1/2)O3-PbTiO3-PbZrO3 System with MnO2 Addition (Pb[(Sb1/2 Nb1/2)0.08 Zr0.49 Ti0.48]O3에서의 MnO2 첨가에 따른 미세구조와 전기적 물성변화에 대한 연구)

  • 강원호;박원규;김호기
    • Journal of the Korean Ceramic Society
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    • v.24 no.6
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    • pp.537-542
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    • 1987
  • The microstructure and electrical properties of Pb[(Sb1/2 Nb1/2)0.08 Zr0.49 Ti0.48]O3 with MnO2 addition have been investigated in this work. The amount of MnO2 addition was 0, 0.4, 0.8, 1.2, 2.0 wt%, respectively. The soild solution range of MnO2 that assumed in this composition according to thevariations of micro-structure and electrical properties was 0.4-0.8 wt%.

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