• Bulletin of the Korean Chemical Society
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• 제18권2호
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• pp.149-151
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• 1997

Barrier height on the surface was monitored at 77 K by observing the inflection of V-I characteristics of ZnO(1010)-ZnO(1010) contact in the surface reaction of oxygen species with carbon monoxide. The contact showed inflections at 10-20 mV and 10-50 mV for the sample adsorbed oxygen at 298 K and 573 K, respectively. When the sample adsorbed oxygen at 573 K was exposed to carbon monoxide at 298 K and 573 K, inflections were observed at 10-40 mV and 10-30 mV, respectively. The results indicated that the adsorption of oxygen on ZnO increased the surface barrier height, and the reaction of carbon monoxide with the oxygen-preadsorbed (at 573 K) ZnO decreased the surface barrier height.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 하계학술대회 논문집
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• pp.1010-1013
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• 2001

Zinc oxide(ZnO) films were prepared by ultrasonic spray pyrolysis on indium (In) films deposited by evaporation and subsequently submitted to rapid thermal annealing (RTA). The RTA was processed in air or a vacuum ambient. The crystallographic properties and surface morphologies of the films were characterized before and after the RTA by X-ray diffraction (XRD) and scanning electron microscopy(SEM), respectively. The resistivity variation of the films with RTA temperature and time was measured by the 4-point probe method. Auger electron spectroscopy(AES) was carried out to figure out the distribution of indium atoms in the ZnO films. The resistivity of the ZnO on In(ZnO/In) films decreased to 2${\times}$10$\^$-3/ $\Omega$cm by diffusion of the In. The In diffusion into the ZnO films roughened the surface of the ZnO films. The results of depth profile by AES showed a hump of In atoms around ZnO/In interface after the RTA at 800$^{\circ}C$, which disappeared by the RTA at 1000$^{\circ}C$. The effects of temperature, time and ambient during the RTA on the structural and electrical properties of the ZnO/In films were discussed.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 제6회 학술대회 논문집 일렉트렛트 및 응용기술연구회
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• pp.52-56
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• 2004

The movement of electron in the semiconductor-gap-semiconductor was observed by the variation of V-I characteristic as a distance two ZnO(1010) single crystals. When the resistance between two crystals was $10^2{\sim}10^4{\Omega}$, V-I characteristics had the pattern of the field emission or ohmic contact. On the other hand, when the resistance was larger than $10^7{\Omega}$ by increasing the distance between two crystals, the effect of surface barrier was prominent. This result leads to the conclusion that both the field emission (or ohmic contact) and the surface barrier effect including the tunneling have the influence on V-I characteristics of mechanically contacted crystals.

• 한국재료학회지
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• 제13권6호
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• pp.365-368
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• 2003

Small amounts of additives such as mol % 0.13 NiO and mol % 0.01 $CaCO_3$were added to Cu-Zn-Mg ferrites. Basic composition of the Cu-Zn-Mg ferrites was $Cu_{Cu}$X/$Fe_{0.054}$ /$Zn_{0.486}$$Mg_{0.407}$ $Fe_{1.946}$ $O_4$(group A) and $Cu_{0.263}$$Fe_{0.027}$ $Zn_{0.503}$ $Mg_{0.262}$ $Fe_{1.973}$ $O_4$(group B). Specimens were sintered at different temperatures (1010, 1030, $1050^{\circ}C$) for 2 hours in air followed by an air cooling. Then, effects of various composition and sintering temperatures on the microstructure and the magnetic properties such as inductions, coercive forces, and initial permeabilities of the Cu-Zn-Mg ferrites were investigated. The average grain size increased with the increase of sintering temperature. The magnetic properties obtained from the aforementioned Cu-Zn-Mg ferrite specimens were 1,724 gauss for the maximum induction, 1.0 oersted for the coercive force, and 802 for the initial permeability. These magnetic properties indicated that the specimens could be utilized as the core of IFT (intermediate frequency transformer) and antenna in the amplitude modulation.

• 대한화학회지
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• 제37권2호
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• pp.183-190
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• 1993

산화아연 단결정(1010) 면에서 나타나는 일산화탄소의 산화반응에 대한 특성을 298∼573 K 의 온도범위에서 두 결정면 사이의 축전용량변화를 추적함으로써 얻어진 절연층의 깊이 변화와 전도도 변화를 동시에 관찰하여 조사하였다. 흡착산소종이 없는 시료에 CO를 주입시켰을 때 373K 이하에서는 절연층의 깊이가 증가되었고, 473K 이상에서는 감소되었으나 그 변화는 $100{\AA}$ 이내로 적게 나타났다. 그러나 산소가 미리 흡착된 시료에 CO를 주입시켰을 때 실온에서는 절연층의 깊이와 전도도의 변화가 거의 없었으며, 373K에서는 절연층의 깊이가 약간 증가되고 전도도는 감소하였다. 또한 473K 이상의 온도에서는 절연층의 깊이가 크게 감소하였으며 전도도는 증가되었다. 이들 결과와 각 온도에서 존재하는 흡착산소종의 형태를 연관시켜 CO의 산화반응에 대한 반응성과 반응경로를 제시하였다.

• 자원환경지질
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• 제32권6호
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• pp.611-631
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• 1999

Enviromental geochemisty and heary metal contamination at the Kongjueil mine creek were underaken on the basis of physicohemical properties and mineralogy for various kinds of water (surface, mine and ground water),soil, precipitate and sediment collected of April and December in 1998. Hydrgeochemical composition of the water samples are characterized by relatively significant enricant of Ca+Na, alkiali ions $NO_3$ and Cl inground and surfore water, wheras the mine waters are relatively eneripheral water of the mining creek have the characteristics of the (Ca+Mg)-$(HCO_3+SO_4)$type. The pH of the mine water is high acidity (3.24)and high EC (613$\mu$S/cm)compared with those of surface and ground water. The range of $\delta$D and $\delta^{18}O$ values (relative to SMOW) in the waters are shpwn in -50.2 to -61.6% and -7.0 to -8.6$\textperthousand$(d value=5.8 to 8.7). Using computer program, saturation index of albite, calcite, dolomite in mine water are nearly saturated. The gibbiste, kaolinite and smectite are superaturated in the surface and ground water, respectively. Calculated water-mineral reaction and stabilities suggest that weathing of silicate minerals may be stable kaolinite owing to the continuous water-rock reaction. Geochemical modeling showed that mostly toxic heavy metals may exist larfely in the from of metal-sulfate $(MSO_4\;^2)$and free metal $(M^{2+})$ in nmine water. These metals in the ground and surface water could be formed of $CO_3$ and OH complex ions. The average enrichment indices of water samples are 2.72 of the groundwater, 2.26 of the surface water and 14.15 of the acid mine water, normalizing by surface water composition at the non-mining creek, repectively. Characteristics of some major, minor and rate earth elements (Al/Na, K/Na, V/Ni, Cr/V, Ni/Co, La/Ce, Th/Yb, $La_N/Yb_N$, Co/Th, La/Sc and Sc/Th) in soil and sediment are revealed a narrow range and homogeneous compositions may be explained by acidic to intermediate igneous rocks. And these suggested that sediment source of host granitic gneiss colud be due to rocks of high grade metamorphism originated by sedimentary rocks. Maximum concentrations of environmentally toxic elements in sediment and soil are Fe=53.80 wt.% As=660, Cd=4, Cr=175, Cu=158, Mn=1010, Pb=2933, Sb=4 and Zn=3740 ppm, and extremely high concentrations are found are found in the subsurface soil near the ore dump and precipitates. Normalizing by composition of host granitic gneiss, the average enerichment indices are 3.72 of the sediments, 3.48 of the soils, 10.40 of the precipitates of acid mine drainage and 6.25 of the soils near the main adit. The level of enerichment was very severe in mining drainage sediments, while it was not so great in the soils. mineral composition of soil and sediment near the mining area were partly variable being composed of quartz, mica, feldspar, chlorite, vermiculite, bethierin and clay minerals. reddish variable being composed of quartz, mica, feldspar, chlorite, vermiculite, bethierin and clay minerals. Reddish brown precipitation mineral in the acid mine drainage identifies by schwertmanite. From the separated mineralgy, soil and sediment are composed of some pyrite, arsenopyite, chalcopyrite, sphalerite, galena, malachite, goethite and various kinds of hydroxied minerals.