酸化物における高温超伝導ならびに熱電能に関する研究

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This paper mainly concerns with the experimental results of a systematic approach to improving the superconducting critical temperature in the Bi-Sr-Ca-Cu-O oxide system as well as an attempt to increasing the thermo-e.m.f. of ferrites. The substitution of transition elements (IV b, V a, and VI a group) or non-transition elements (IV b and V b group) for Bi ions in the oxide was performed, and the effect of substitution on Tc, Jc, magnetization, temperature dependence of resistivity or magnetization and variation of solid phase was investigated. It was found that the substitution of P is the most effective and then the high Tc phase is formed in a large quantity by replacing Bi ions with 30% of P ions. Measurements were carried out of the thermo-e.m.f. of a thermoelectric junction composed of bulk ferrites or double-layered ferrite films as a function of the temperature. Thermo-e.m.f. of ferrites was much larger than that of the conventional thermoelectric junction made of metals. Application of a magnetic field reduced the thermoelectric power. A positive or negative thermo-e.m.f. was observed depending on the difference in the combination of ferrites. The origin of this phenomena was examined from various point of views, such as n-type or p-type ferrites and ion conduction.
帝京平成大学の論文
1997-12-28