• 아시안잔디학회지
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• 제11권4호
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• pp.289-294
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• 1997

The cycles of heavy metals, mercury, lead and cadmium, were investigated on in dynamic grassland ecosystems at a steady state in Zoysia japonica and Miscanthus sinensis in Mt. Kwanak, Korea. Estimates of decay constants of heavy metals based on experimental and methomatical model, were Hg 0.14, Pb 0.17 and Cd 0.41 of Z. japonica grassland, and Hg 0.33, Pb 0.13 and Cd 0.56 of M sinensis grassland. The durations of reaching half of initial amounts in Z. japonica and M. sinensis grassland, were Hg 4.95, Pb 4.07 and Cd 1.69 years, and Hg 2.10, Pb 5.33 and Cd 1.24 years respectively. Times needed for 99% decomposed were longer in Z. japonica than M. sinensis grassland. Decay velocity of constituents of surface soil layers were more rapidly in M. sinensis than Z. japonica grassland. Key words: Cycles of heavy metals, Mercury, Lead, Cadmium, Zoysia japonica. Miscanthus sineusis, Mt. Kwanak, Decay constants.

• 한국광물학회지
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• 제28권2호
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• pp.187-193
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• 2015

익산 미륵사지 석탑의 사리공 내에서 출토된 납유리 9점의 납동위원소비를 분석하여 납 원료의 산지를 추정하고, 이를 왕궁리 출토 납유리의 연구결과와 비교하여 상관관계를 알아보고자 하였다. 납유리는 주화학성분 분석결과, PbO가 약 70 wt.%, $SiO_2$가 약 30 wt.% 함유된 전형적인 $PbO-SiO_2$계의 유리였다. 납동위원소비를 이용한 납유리의 원료산지 추정결과, 기존 동북아시아 납동위원소비 분포도로는 대부분이 한국북부의 방연석 광산에 속하는 것으로 나타났다. 반면, 한반도 납동위원소비 분포도로는 한국남부의 방연석 광산이 납유리의 주요 원료 산지로 추정할 수 있어 두 분포도의 결과가 상이하게 나타났다. 또한 동일지역, 동시대에 조성된 것으로 알려진 왕궁리 출토 납유리의 기존 연구데이터와 비교한 결과, 납 원료의 산지가 서로 유사한 것으로 판단된다.

• 대한화학회지
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• 제6권2호
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• pp.133-142
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• 1962

This study was carried out to investigate the lead-bismuth-sodium ternary system which a basis of the Dittmer method as a part of "the fundamental study of pyrometallurgical debismuthizing of lead". Thermodynamic properties of each liquid Pb-Bi, Pb-Na binaries as well as liquid Pb-Bi-Na ternary solution were measured by e.m.f. of these concentration cells, and those of each component were also determined. Furthermore, iso-activity lines including Pb rich side composition of Pb-Bi-Na ternary solution were determined. The relationship between those thermodynamic characteristics and tendency of intermetallic compound formation was discussed through the above experiments.

• 한국세라믹학회지
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• 제48권1호
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• pp.99-105
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• 2011

Lead titanate ($PbTiO_3$) powder was prepared from lead nitrate ($Pb(NO_3)_2$) and titania ($TiO_2$) by hydrothermal route. Phase formation process was investigated by observing the phases formed in various experimental conditions like different KOH concentration, reaction temperature and time. $PbTiO_3$ powder was fabricated when the KOH concentration was 0.8M or higher. An intermediate compound, $PbTi_{0.8}O_{2.6}$, was formed at first by a reaction between PbO and $TiO_2$ and changed into $PbTiO_3$ powder with a perovskite crystal structure. A $PbTiO_3$ phase was formed in a shorter time when a KOH concentration was increased from 0.8M to 8M because a driving force for a $PbTiO_3$ formation was increased due to an increase in a degree of supersaturation. And $TiO_2$ (rutile) and $3PbO{\cdot}H_2O$ were observed at room temperature in a 0.8M KOH solution and $TiO_2$(rutile) and PbO (litharge) in a 8M KOH. A $PbTiO_3$phase was also formed in a shorter time at a higher reaction temperature as a reaction temperature influenced the rates for a dissolution and a precipitation.

• 한국전기전자재료학회논문지
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• 제33권4호
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• pp.315-320
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• 2020

Methylammonium lead iodide (MAPbI₃) thin films were grown at low temperatures on glass substrates via 3-zone chemical vapor deposition. Lead iodide (PbI₂) and lead bis (dipivaloylmethanate) [Pb(dpm)₂] precursors were used as lead sources. Due to the high sublimation temperature (~400℃) of the PbI₂ precursor, a low substrate temperature could not be constantly maintained. Therefore, MAPbI₃ thin films degraded into the PbI₂ phase. In contrast, for the Pb(dpm)₂ precursor, a substrate temperature of ~120℃ was maintained because the sublimation temperature of Pb(dpm)₂ is as low as 130℃ at a high vapor pressure. As a result, high-quality MAPbI₃ thin films were successfully grown on glass substrates using Pb(dpm)₂. The rms (root-mean-square) roughness of MAPbI₃ thin films formed from Pb(dpm)₂ was as low as ~19.2 nm, while it was ~22.7 nm for those formed using PbI₂. The grain size of the films formed from Pb(dpm)₂ was as large as approximately 350 nm.

• Environmental Engineering Research
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• 제11권1호
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• pp.54-61
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• 2006

An electron probe microanalysis (EPMA) investigation can provide quantitative and qualitative insight into the nature of the surface and bulk chemistry on solidified waste forms(SWF). The proportion of Pb in grain areas is below 0.3 wt. %, and the proportion near the border of the grain slightly increases to 0.98 wt. % but in the inter-particle areas farther from the grain, the concentration of Pb markedly increases. It is apparent that very little Pb diffuses into the tricalcium silicate($C_3S$) particles and most of the Pb exists as precipitates of sulfate, hydroxide, and carbonate in the cavity areas between $C_3S$ grains. Calcite additions on Pb-doped SWF are also observed to induce deeper incorporation of lead into the cement grains with EPMA line-analysis of cross-sections of cement grains. The line-analysis reveals the presence of $0.2{\sim}5$ weight % Pb over $5\;{\mu}m$ from cement grain boundaries. In the inter-particle areas, the ratio of Ca, Si, Al and S to Pb is relatively similar even at some distance from the grain border and the Pb (wt. %) ratio is reasonably constant throughout the whole inter-particles area. It is apparent that the enhanced development of C-S-H on addition of calcite can increasingly absorbs lead species within the silica matrix.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1995년도 하계학술대회 논문집 C
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• pp.1048-1050
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• 1995

Lead-acid battery is used widely as a power source at a automobile, industrial machines, folk lifts, U.P.S. etc. Lead-acid battery is cheaper than arty other secondary battery, but this battery has many disadvantages such as heavy, low energy density, environment problem etc. In this article, we introduce cyclic voltammetry methods to investigate corrosion behaviour of positive grids of Pb-Ca alleys.

• 보존과학연구
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• 통권15호
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• pp.52-58
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• 1994

To protect corrosion of bronze roofing tile for Choson Royal Historic Museum, lead coating on tile was performed by electroplating method with thickness of $35\mum$. Lead coated tile samples were inverstigated what corrosion products were formed with color changes on them by testing Accelerated Weathering. No sulfides were formed on samples contacting with 300ppm sulfur dioxide and any color changes were not found. In Accelerated Weathering test, White hydrocerussite, basic lead carbonate($2PbCO_3Pb(OH)_2$) having protective structure made of compact adhering crystals.

• Bulletin of the Korean Chemical Society
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• 제16권12호
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• pp.1148-1152
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• 1995

Oxidative dimerization of methane to C2-hydrocarbons was performed over lead aluminate spinel catalysts. These spinel catalysts were prepared by co-precipitation, aerogel, and sol-gel methods. The active phase of lead aluminate oxides was found to be PbAl2O4 spinel. The activities of the catalysts were strongly dependent on the preparation method as well as the composition of PbAl2O4 phase. The proper oxygen mobility of PbAl2O4 spinel oxides appeared to be important to get high catalytic activity and selectivity for C2-hydrocarbon formation.

• Bulletin of the Korean Chemical Society
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• 제20권3호
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• pp.355-361
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• 1999

To improve the volatility and stability of lead complexes, the principle of stabilization by saturating the metal coordination sphere by intramolecular coordination through a β-diketonates with an ethereal group has was tested. Several new lead complexes with alkoxyalkyl-substituted β-diketonates, Pb(R1C(O)CHC(O)(CH2)3OR2)2(Rl=t-Bu, Me, OMe, i-Pr, R2=Me, Et), or carboxylate, Pb(OC(O)(CH2)3OEt)2, were prepared by the reaction between Pb(OAc)2 and corresponding alkoxyalkyl-substituted β-diketonates, and they were found to have a viscous liquid phase. The nature of the head (β-diketonate or carboxylate) or tails and substituents of β-diketonates appeared not to be important for the formation of the liquid phase. It is worth mentioning that Pb(OAc)2, which has limited use due to its low solubility, was successfully adopted as a starting material for the preparation of new lead complexes. Easy hydrolysis, reaction with HCl, and 13C NMR spectra indicated that tail portions were not coordinated to the metal as a copper derivative, Cu(t-BuC(O)CHC(O)(CH2)3OMe)2. All these complexes were not volatile enough for the MOCVD experiments, but a methyl derivative, Pb(MeC(O)CHC(O)(CH2)3OEt)2, showed some sublimation. The methoxy derivative, Pb(MeOC(O)CHC(O)(CH2)3OEt)2, was thermally unstable due to possible equilibrium between species coordinating with a keto oxygen atom and an ethereal atom of a methoxy group, which was confirmed by IR and 13C NMR spectra.