• Journal of the Korean Electrochemical Society
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• v.18 no.2
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• pp.51-57
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• 2015

We report the effect of the impurities including water and bromide in the propylmethylpyrrolidinium bis(trifluoromethanesulfonyl)imide (PMPyr-TFSI) on the electrochemical performance of lithium ion batteries. The several kinds of PMPyr-TFSI electrolytes with different amount of impurities are applied as the electrolyte to the cell with the high potential electrode, $LiNi_{0.5}Mn_{1.5}O_4$ spinel. It is found that the impurities in the electrolytes cause the detrimental effect on the cell performance by tracing the cycleability, voltage profile and Coulombic efficiency. Especially, the polarization and Coulombic efficiency go to worse by both impurities of water and bromide, but the cycleability was not highly influenced by bromide impurity unlike the water impurity.

• Bulletin of the Korean Chemical Society
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• v.35 no.11
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• pp.3275-3279
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• 2014

A mass balance method for purity assessment of thermolabile organic reference materials was established by combining several techniques, including liquid chromatography with UV/VIS detector (LC-UV), Karl-Fischer (K-F) Coulometry, and thermal gravimetric analysis (TGA). This method was applied to three fluoroquinolones like enrofloxacin, norfloxacin and ciprofloxacin. LC-UV was used to analyze structurally related organic impurities based on UV/VIS absorbance spectra obtained in combination with LC separation. For all three organic reference materials, the UV/VIS spectra of the separated impurities were similar to that of the major component of the corresponding materials. This indicates that the impurities are structurally related to the respective reference material sharing common chromophores. Impurities could be quantified by comparing their absorbances at the wavelength of maximum absorbance (${\lambda}_{max}$). The water contents of the reference materials were measured by K-F Coulometry by an oven-drying method. The total inorganic impurities contents were assayed from ash residues in TGA analysis with using air as a reagent gas. The final purities estimated from results of those analytical techniques were assigned as ($99.91{\pm}0.06$), ($97.09{\pm}0.17$) and ($91.85{\pm}0.17$)% (kg/kg) for enrofloxacin, norfloxacin and ciprofloxacin, respectively. The assigned final purities would be applied to the reference materials which will be used as calibrators for the certification of those compounds in matrix CRMs as starting points for the traceability of their certified values to SI units.

• ETRI Journal
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• v.24 no.4
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• pp.270-279
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• 2002

We present a self-consistent numerical method for calculating the conduction-band profile and subband structure of AlGaN/GaN single heterojunctions. The subband calculations take into account the piezoelectric and spontaneous polarization effect and the Hartree and exchange-correlation interaction. We calculate the dependence of electron sheet concentration and subband energies on various structural parameters, such as the width and Al mole fraction of AlGaN, the density of donor impurities in AlGaN, and the density of acceptor impurities in GaN, as well as the electron temperature. The electron sheet concentration was sensitively dependent on the Al mole fraction and width of the AlGaN layer and the doping density of donor impurities in the AlGaN. The calculated results of electron sheet concentration as a function of the Al mole fraction are in excellent agreement with some experimental data available in the literature.

• Journal of Industrial Technology
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• v.10
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• pp.83-88
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• 1990

The samples used for this work were low grade c1ay($Fe_2O_3$ : 2.90%, $TiO_2$ : 1.65%) produced from Youngsan-po district, and for the iron-bearing impurities removal having a bad influence on Kaoline sample was carried out column floatatoin using Oleic acid, Potassium oleat, Aero 840 promotor, Aero 870 promotor and Keroseneas collectors. For removal of the iron-vearing impurities from the kaoline, investigated first chemical composition size distribution of Kaoline sample, also performanced a basic study on pulp density, collector and pH change on a sort of frother. The flotation separation of impurities from kaoline can be achieved by using both oleic acid and Aero 840 promotor as collectors within narrow acid limits(pH 2-3). Pine oil was more effective frother than MIBC with olelic acid as aa collector.

• YAKHAK HOEJI
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• v.7 no.2_3
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• pp.67-71
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• 1963

Studies the reaction mechanism and optimal reaction condition of the process of preparing sodium isocyanate, by means of heating of sodium carbonate and urea. Proposing, at the sametime, the quantitative analyzing method of sodium isocyanate in the presence of impurities of $Na_{2}CO_{3}$, urea and biuret. 1. Sodium isocyanate could be prepared by means of heating reaction of sodium carbonate and urea. 2. Adding urea into the heated sodium carbonate is reasonable. 3. Quantitative analysis of sodium isocyanate in the presence of impurities, $Na_{2}CO_{3}$, urea and biuret could be done by the following method:-adding nitrobarite solution into sample solution in order to remove $CO_{3}"$ and neutralize the solution, filtering off $BaCO_{3}$, and then precipitating isocyanate as a silver salt, filtering off AgNCO, and then, titrating remaining $AgNO_{3}$ with $NH_{4}SCN$, (indicator $FeNH_{4}(SO_{4})_{2})$/TEX>

• Economic and Environmental Geology
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• v.32 no.4
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• pp.399-409
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• 1999

Mullitization of kaolinite and dickite was examined with special attention to the influence of polytypism and impurities on the phase transformation. The phase transformation sequence in dickite is identical with that in kaolinite except that cristobalite is crystallized at $50^{\circ}C$ higher temperature in dickite. Difference in phase transformation above $1000^{\circ}C$ in kaolin minerals is attributed to the different crystal structures of metadickite and metakaolinite on the effect of impurities. A part of quartz is transformaed into cristobalite. Spinel-type phase produced in disordered kaolins including illite occurs over a short range of temperatures. Primary mullite is transformed into orthorhombic mullite at higher temperature as well. These results sustain the idea that disintegration of methkaolin and the spinel-type phase supplies extra sillica and promotes the growth of mullite cristobalite.

• 한국신재생에너지학회:학술대회논문집
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• 2008.05a
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• pp.526-529
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• 2008

The effect of air impurities on PEMFC performances were studied using electrochemical analysis, such as OCV monitoring, polarization, constant current operation, and electrochemical impedance spectroscopy. The nitrogen dioxide in air lowered the operation voltage at 1 A/$cm^2$ by 160 mV (10 ppm) and 227 mV (100 ppm), while the carbon monoxide effect was relatively not significant (30 mV at 100 ppm). For both nitrogen dioxide and carbon monoxide, the performances were largely recovered when pure air was provided again. Further study for additional air impurities and simulated air are under progress to provide fundamental data for the design of fuel cell vehicles.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1997.04a
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• pp.130-134
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• 1997

The structural defects, impurities, degree of crosslinking and shrinkage of 38 field-aged distribution cables have been analyzed. For the comparison of data, 9 new cables were also subjected to an analysis. It is observed that the structural defects and degree of crosslinking show a radial profile. The structural defects are different depending on the manufacturer. A large amount of impurities is present in the insulation shield, which hold true for the new cables manufactured recently. The degree of crosslinking near both shields is lower than that at the central region of the insulation layer. It was also found that, in some cal)toes, the ins난lation was not fully crosslinked. The shrinkage of field-aged cables is higher than that of new cables.

• 한국초전도학회:학술대회논문집
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• v.9
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• pp.99-101
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• 1999

To improve the texture and the hardness of Ni substrates, we added impurities such as Mn, Fe, Co, Cu and Cr and investigated the effect of impurities on the texture and the hardness of Ni tapes. The Ni tapes with 0.2% Co, Cr, Cu, showed poor in-plane textures. However, the Ni tapes with 0.1 ${\sim}$ O.2% Mn (or Fe), showed much better textures. We'll describe the detailed effects of the amount of Mn impurities.

• Proceedings of the Materials Research Society of Korea Conference
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• 2011.05a
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• pp.29.2-29.2
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• 2011

B-site substitution with isovalent and donor impurities was compared in terms of the piezoelectric properties of Bi-based ABO3 perovskite ceramics. X-ray diffraction study revealed that both impurities bring about degradation in their ferroelectric properties as well as piezoelectric characteristics. However, there existed a difference between the isovalent and heterovalent impurities that influence a phase transformation of ferroelectric anisotropic-to-electrostrictive pseudocubic symmetry. Based upon analyses including the crystal, microstructure, dielectric, ferroelectric properties, we believed that A-site vacancies in the ABO3 ceramic significantly contribute to a ferroelectric-nonpolar phase transition, which give rise to lead to a giant strains. The present paper will discuss the origin of giant strains in Bi-based perovskite ceramics.