• 제목/요약/키워드: $O_{3}$ concentration

검색결과 5,143건 처리시간 0.032초

Controllability of Structural, Optical and Electrical Properties of Ga doped ZnO Nanowires Synthesized by Physical Vapor Deposition

  • Lee, Sang Yeol
    • Transactions on Electrical and Electronic Materials
    • /
    • 제14권3호
    • /
    • pp.148-151
    • /
    • 2013
  • The control of Ga doping in ZnO nanowires (NWs) by physical vapor deposition has been implemented and characterized. Various Ga-doped ZnO NWs were grown using the vapor-liquid-solid (VLS) method, with Au catalyst on c-plane sapphire substrate by hot-walled pulsed laser deposition (HW-PLD), one of the physical vapor deposition methods. The structural, optical and electrical properties of Ga-doped ZnO NWs have been systematically analyzed, by changing Ga concentration in ZnO NWs. We observed stacking faults and different crystalline directions caused by increasing Ga concentration in ZnO NWs, using SEM and HR-TEM. A $D^0X$ peak in the PL spectra of Ga doped ZnO NWs that is sharper than that of pure ZnO NWs has been clearly observed, which indicated the substitution of Ga for Zn. The electrical properties of controlled Ga-doped ZnO NWs have been measured, and show that the conductance of ZnO NWs increased up to 3 wt% Ga doping. However, the conductance of 5 wt% Ga doped ZnO NWs decreased, because the mean free path was decreased, according to the increase of carrier concentration. This control of the structural, optical and electrical properties of ZnO NWs by doping, could provide the possibility of the fabrication of various nanowire based electronic devices, such as nano-FETs, nano-inverters, nano-logic circuits and customized nano-sensors.

고농도 $NO_x$ 감지용 $In_2O_3$ 후막가스센서의 Al, Ru 및 $SnO_2$ 첨가에 의한 특성 향상 (Gas Sensing Characteristics of Catalyst-added $In_2O_3$ Thick Film for Detecting $NO_x$ of High Concentration)

  • 박종현;김동현;이종영;김광호
    • 한국세라믹학회지
    • /
    • 제36권12호
    • /
    • pp.1322-1326
    • /
    • 1999
  • In2O3 thick film gas sensor for detecting NOx gas of high concentration was fabricated by a screen printing technique. This work focussed on investigation of the change of sensitivity to NOx gas with firing temperatures of sensing layer and on improvement of the sensitivity by adding catalysts such as Al,. Ru, and SnO2 The cross sensitivites of sensor to CO, H2, CH4 and i-C4H10 gases were also examined under NO2 gas concentration of 200ppm Pure In2O3 gas sensor prepared at a firing temperature of 50$0^{\circ}C$ showed a maximum sensitivity to NOx gas at the operating temperature of 40$0^{\circ}C$ Al(0.004 wt%)-In2O3 sensor largely improved the sensitivities to both NO2 and NO gas and showed a superior selectivity compared with other gas sensors.

  • PDF

1%미만의 부피비를 가지는 알루미나 나노유체의 유효 열전도도 (Effective Thermal Conductivities $Al_2O_3$ Nanoparticles Suspended in Water with Low Concentration)

  • 이병호;김준호;공유찬;장석필;구자예
    • 대한기계학회:학술대회논문집
    • /
    • 대한기계학회 2007년도 춘계학술대회B
    • /
    • pp.2177-2181
    • /
    • 2007
  • In this paper, effective thermal conductivities of water-based $Al_2O_3$-nanofluids with low concentration from 0.01 vol. % to 0.3 vol. % are experimentally obtained by transient hot wire method (THWM). The water-based $Al_2O_3$-nanofluids are manufactured by two-step method which is widely used. To examine suspension and dispersion characteristics of the water-based $Al_2O_3$-nanofluids, Zeta potential as well as transmission electron micrograph (TEM) is observed. We confirm the manufactured $Al_2O_3$-nanofluids have good suspension and dispersion. The effective thermal conductivities of the water-based $Al_2O_3$-nanofluids with low concentration are enhanced up to 1.64% compared with that of DI water at $21^{\circ}C$. In addition, experimental results are compared with theoretical results from Jang and Choi model.

  • PDF

산소 가스를 이용한 산화아연의 전자 농도와 광발광 세기 조절 (Control of electron concentration and photoluminescence intensity of ZnO thin films using oxygen gas)

  • 강홍성;김재원;이상렬
    • 한국전기전자재료학회:학술대회논문집
    • /
    • 한국전기전자재료학회 2004년도 하계학술대회 논문집 Vol.5 No.1
    • /
    • pp.185-187
    • /
    • 2004
  • The electron concentration of ZnO thin film fabricated by pulsed laser deposition was controlled by varying oxygen gas pressure. The electron concentration of ZnO was increased from $10^{17}\;to\;10^{19}/cm^3$ as oxygen gas pressure increased from 20 mTorr to 350 mTorr. Ultraviolet(UV) intensity of photoluminescence of ZnO was controlled, too. UV intensity of ZnO was increased as oxygen gas pressure increased from 20 mTorr to 350 mTorr. The relation between electron concentration and UV intensity was investigated.

  • PDF

차량용 산소발생기의 성능 측정 (The Evaluation of Oxygen Generator Performance For Car)

  • 송근호;유진호;김정은;장화익;이광래
    • 산업기술연구
    • /
    • 제25권A호
    • /
    • pp.151-156
    • /
    • 2005
  • Auto exhausts and air pollution can become trapped in the cabin of vehicle, reducing the amount of oxygen available for breathing. Driver may feel sleepy, headaches, nausea, confusion, dizziness and lower levels of oxygen can damage the driver's general health. Consequently, oxygen generator purified oxygen into the car to help driver get the oxygen driver's body needs. In this study, in order to evaluate the oxygen generator performance, the samples that the various conditions(humidity(50%, 100%), flow and oxygen concentration) were examined. There were three types of oxygen generator; sample 1($2.5{\ell}/min$, $36%O_2$), sample 2($4.5{\ell}/min$, $41%O_2$) and sample 3($5{\ell}/min$, $39%O_2$). As the humidity increased from 50% to 100%, the oxygen concentration of the sample 1(36%), 2(41%) and 3(39%) was reduced $31%O_2$, $38%O_2$ and $38%O_2$, respectively. Also, the each sample measured that effect of human in car on oxygen concentration, if the oxygen concentration is one person in car, each sample of oxygen concentration was $20.8%O_2$, $23.7%O_2$ and $21.2%O_2$. From the above results, it was shown that oxygen generator for car, if the oxygen concentration is increased, effect of humidity is reduced, and that in the sample of supplying a high-rate of oxygen, the oxygen concentration is increased. It was suggested that effect of humidity on oxygen generator for car can be reduced according to the supply of oxygen.

  • PDF

임간초지 개발에 관한 연구 X III. 차광조건하에서 칼리시비수준이 계절별 , 생육시기별 목초의 건물생산과 사료가치 및 질산태질소 함량에 미치는 영향 (Studies on the Grassland Development in the Forest XIII. Effect of potassium fertilization on grass production, nutritive value and nitrate nitrogen concentration by growing senson and growth stage under shading condition)

  • 서성
    • 한국초지조사료학회지
    • /
    • 제13권2호
    • /
    • pp.93-98
    • /
    • 1993
  • To determine the effects of potassium($K_2O$) fertilization level(0, 100, 200 and 300 kg/ha/year) on the growth, dry matter(DM) yield, nutritive value and nitrate nitrogen($NO_3$-N) concentration of grasses grown under shading condition, this experiment was carried out in Grassland Div., LES, 1989. The plants were sampled on different growing seasons (spring, summer and autumn) and growth stages (grazing and soiling), respectively. Shade was controlled artificially ca. 45-50%, and the level of nitrogen fertilization was 200 kg/ha/year in all treatments. Higher DM was produced in spring 1, 453 kg at grazing and 2, 364 kg/ha at soiling stage, and DM production was increased with increasing level of $K_2O$. In this experiment, the optimum amount of $K_2O$ fertilizer was 200 kg/ha. The neutral detergent fiber, acid detergent fiber, DM digestibility, and relative feed value of grasses were not affected by $K_2O$ fertilization, regardless of growing season and growth stage. The $NO_3$-N concentration of grasses grown in spring was very low (ca. 1.0%), regardless of growth stage and $K_2O$ level. However, $NO_3$-N concentration was very high in summer and autumn season, also $NO_3$-N was decreased significantly with increasing level of $K_2O$ fertilization (P<0.05). Application of $K_2O$ fertilizer, therefore, is thoughs to be desirable for reducing $NO_3$-N concentration of grasses, especially in summer and autumn season. So annual split fertilization of $K_2O$ could be recommended on woodland pasture.

  • PDF

Theoretical Calculation and Experimental Verification of the Hf/Al Concentration Ratio in Nano-mixed $Hf_xAl_yO_z$ Films Prepared by Atomic Layer Deposition

  • Kil, Deok-Sin;Yeom, Seung-Jin;Hong, Kwon;Roh, Jae-Sung;Sohn, Hyun-Cheol;Kim, Jin-Woong;Park, Sung-Wook
    • JSTS:Journal of Semiconductor Technology and Science
    • /
    • 제5권2호
    • /
    • pp.120-126
    • /
    • 2005
  • We have proposed a characteristic method to estimate real composition when multi component oxide films are deposited by ALD. Final atomic concentration ratio was theoretically calculated from the film densities and growth rates for $HfO_2$ and $Al_2O_3$ using ALD processed HfxAhOz mms.W e have transformed initial source feeding ratio during deposition to fins] atomic ratio in $Hf_xAl_yO_z$ films through thickness factors ($R_{HFO_2}$ ami $R_{Al_2O_3}$) ami concentration factor(C) defined in our experiments. Initial source feeding ratio could be transformed into the thickness ratio by each thickness factor. Final atomic ratio was calculated from thickness ratio by concentration factor. It has been successfully confirmed that the predicted atomic ratio was in good agreement with the actual measured value by ICP-MS analysis.

음/비이온계 혼합계면활성제 용액에서 $\alpha-Fe_2O_3$ 입자의 분산안정성 (The Dispersion Stability of $\alpha-Fe_2O_3$ Particulate Soil in the Anionic/Nonionic Mixed Surfactant Solution)

  • 정선영;강인숙
    • 한국의류학회지
    • /
    • 제28권6호
    • /
    • pp.854-861
    • /
    • 2004
  • To estimate dispersion stability of particles in anionic and nonionic surfactant mixed solution, suspending power was examined as functions of duration time of suspension, ionic and nonionic surfactant mixed ratio, surfactant concentration, kinds of electrolyte, ionic strength and mole numbers of oxyethylene additions to nonionic surfactant using $\alpha$-Fe$_2$O$_3$ particle as the model of particulate soil. The suspending power of anionic and nonionic surfactant mixed solution was relatively higher than that of anionic and nonionic surfactant single solution regardless of solution concentration. The suspending power was gradually decreased with increasing duration time of suspension. In the absence of electrolyte, the effect of surfactant concentration on suspending power was small but in solution with electrolyte, suspending power was lowest at 1 % surfactant concentration. With 1${\times}$10$^{-3}$ ionic strength and polyanionic electrolyte in solution, the suspending power was high but effects of oxyethylene mole number to nonionic surfactant on suspending power was small. Generally the suspending power was gradually increased with decreasing the particle size. Hence the suspending power was inversely related to the particle size.

Phosphorus-Doped ZnO 나노로드의 열처리 효과 (Annealing Effect of Phosphorus-Doped ZnO Nanorods Synthesized by Hydrothermal Method)

  • 황성환;문경주;이태일;명재민
    • 한국재료학회지
    • /
    • 제23권5호
    • /
    • pp.255-259
    • /
    • 2013
  • An effect of thermal annealing on activating phosphorus (P) atoms in ZnO nanorods (NR) grown using a hydrothermal process was investigated. $NH_4H_2PO_4$ used as a dopant source reacted with $Zn^{2+}$ ions and $Zn_3(PO_4)_2$ sediment was produced in the solution. The fact that most of the input P elements are concentrated in the $Zn_3(PO_4)_2$ sediment was confirmed using an energy dispersive spectrometer (EDS). After the hydrothermal process, ZnO NRs were synthesized and their PL peaks were exhibited at 405 and 500 nm because P atoms diffused to the ZnO crystal from the $Zn_3(PO_4)_2$ particles. The solubility of the $Zn_3(PO_4)_2$ initially formed sediment varied with the concentration of $NH_4OH$. Before annealing, both the structural and the optical properties of the P-doped ZnO NR were changed by the variation of P doping concentration, which affected the ZnO lattice parameters. At low doping concentration of phosphorus in ZnO crystal, it was determined that a phosphorus atom substituted for a Zn site and interacted with two $V_{Zn}$, resulting in a $P_{Zn}-2V_{Zn}$ complex, which is responsible for p-type conduction. After annealing, a shift of the PL peak was found to have occurred due to the unstable P doping state at high concentration of P, whereas at low concentration there was little shift of PL peak due to the stable P doping state.

Polarography에 依한 Titanium Oxalato 및 Oxalatous Complex에 關한 硏究 (Polarographic Study of Titanium Oxalato and Oxalatous Complex)

  • 김황암;한동진
    • 대한화학회지
    • /
    • 제9권2호
    • /
    • pp.71-74
    • /
    • 1965
  • Reduction of Ti(Ⅳ)-oxalate complex on dropping mercury electrode has been studied as a function of oxalate concentration and of pH varied with HCl. Assuming there are equilibrium $TiO(C_2O_4)_2= \;+\;2H^+\;=\;Ti^{+4}\;+\;2C_2O_4\;=\;+\;H_2O,\;K_4$ in addition to $TiO(C_2O_4)_2\;^=\;=\;TiO^{++}\;+\;2C_2O_4=\;K_2\;Ti(C_2O_4)_2\;^-\;=\;Ti^{+3}\;+\;2C_2O_4=\;K_3$ in the system cathodic wave has been well explained for that pH is higher than 0.5. The equilibrium constants $K_2,\;K_3$ and $K_4$ have been to be $2{\times}10^{-12},\;5{\times}10^{-13}$ and $10^{-11}$, respectively. The reduction of Ti(Ⅳ)-oxalate system is $Ti^{+4}\;+\;e\;{\to}\;Ti^{+3}$ in the concentration of hydrochloric acid, higher than 3M.

  • PDF