| Project/Area Number |
61550561
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
工業分析化学
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| Research Institution | Tokyo University of Science |
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Principal Investigator |
TANAKA Tatsuhiko Science University of Tokyo, Faculty of Engineering, 工学部第1部, 講師 (40084389)
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| Project Period (FY) |
1986 – 1988
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| Project Status |
Completed (Fiscal Year 1988)
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| Budget Amount *help |
¥1,600,000 (Direct Cost: ¥1,600,000)
Fiscal Year 1988: ¥100,000 (Direct Cost: ¥100,000)
Fiscal Year 1987: ¥300,000 (Direct Cost: ¥300,000)
Fiscal Year 1986: ¥1,200,000 (Direct Cost: ¥1,200,000)
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| Keywords | High-precision coulometric titration / Determination of niobium / Determination of tin / Determination of gallium / Superconducting material / Stoichiometric analysis of superconductor / Nonstoichiometry / Nb_3Sn / 不定比組成の精密測定 / 精密電量滴定 / 超伝導ニオブ化合物 / ストイキオメトリー |
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| Research Abstract |
A slight deviation from stoichiometry of superconducting material influences remarkably on the critical temperature. Therefore, the accurate evaluation of the nonstoichiometry is required. In this investigation, niobium, tin and gallium were accurately assayed by high-precision coulometric titration with an amperometric end-point detection.
Niobium(V) was reduced to niobium(III) by Jones reductor in 3 M sulfuric acid. The sample solution was kept in the reductor for about 16 h. The reduced niobium(III) was reoxidized to niobium(V) with a large excess of ferric ion, and the ferrous ion produced was titrated with electrogenerated mangnese(III) fluoride.The operations of reduction and titration were carried out in an atmosphere of nitrogen. The proposed coulometric titration permits accurate and precise determination of niobium which is matrix constituent in a sample.
Tin(IV) was reduced to tin(II) by a hot antimony column in 3 M hydrochloric acid, and the produced tin(II) was titrated with electrolytically generated iodine. The optimum conditions for the determination of tin were found and the precision of the results was one order of magnitude better than that of usual method.
The method for the determination of gallium was based on the reaction of gallium(III) with a known excess of ESTA, the unconsumed EDTA being back-titrated with cadmium(II) electrogenerated from an amalgamated cadmium anode. The generation of cadmium(II) proceeded with 100% current efficiency over a wide range of current density, when both sodium chloride and sodium acetate concentrations were higher than 0.1 M. The use of cadmium(II) instead of zinc(II) as a coulometric titrant for complexometry reduced the error in amperometric indication of the end point, and the standard deviation of the results was about 0.01%.
In conclusion, the precision obtained by the proposed methods is enough to be used to measure the stoichiometric composition of superconducting material such as Nd3Sn and V3Ga.
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