Superconductor technology: apparatus – material – process – High temperature – per se – Having tc greater than or equal to 150 k
Patent
1989-02-07
1993-12-07
Silbaugh, Jan H.
Superconductor technology: apparatus, material, process
High temperature , per se
Having tc greater than or equal to 150 k
209 2, 209 11, 209212, 505932, H01L 3912, B03B 100
Patent
active
052683532
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to a method for manufacturing an oxide superconductor and more particularly to a novel method for separating superconductor powder.
BACKGROUND ART
FIG. 1 is an explanatory view showing the conventional method for manufacturing an oxide superconductor disclosed for example in a paper entitled "Manufacture and Evaluation of Ceramics High-Temperature Superconducting Material", Koji Kishidera, Industrial Chemical Engineering, Department of Engineering, Tokyo University published at a symposium entitled "Manufacture and Application of High-Temperature Superconducting Material" on Apr. 6, 1987. As the first step, an oxide of lanthanoid metal and alkaline earth metal and an oxide of copper are weighed (1). The second step is mixing (2) in a mortar, the third step is pre-baking (3) at a temperature of several hundred degrees, the fourth step is crushing and mixing (4), the fifth step is shaping (5) into a desired configuration, and the sixth step is final baking at a temperature from 900.degree. C. to 1100.degree. C.
This method is called the powder mixing method, and one example of the characteristics of the resistance relative to temperature of an oxide superconductor manufactured by this method is illustrated in a characteristic curve 100 in FIG. 2.
In FIG. 2, the axis of abscissa represents temperature and the ordinate represents resistance. The point E is the temperature usually referred to as the onset at which the change in resistance begins to rapidly decrease, and the point F is the temperature usually referred to as the offset at which the resistance disappears.
The change in resistance according to temperature of the oxide superconductor manufactured by the conventional manufacturing method is as shown by the characteristic curve 100, from which it is seen that the temperature difference between the point E of the onset and the point F of the offset is large, making the offset or the temperature at which the resistance disappears low, so that the necessary low temperature becomes even lower and the characteristics of the resulting superconductor are inferior. These considerations pose a problem.
DISCLOSURE OF THE INVENTION
This invention has been made in order to solve the above-discussed problem and has as its object the provision of a method for manufacturing an oxide superconductor which has a high offset temperature and a small temperature difference between the onset and the offset.
The method for manufacturing an oxide superconductor of the present invention comprises the step of mixing and baking a plurality of different kinds of ingredient material at a predetermined proportion and obtaining a mixed powder having an oxide superconducting powder as a main ingredient, and a step of placing a magnet close to said mixed powder to separate said oxide superconducting powder through the utilization of the magnetic repulsive force due to the Meissner effect of the superconductor.
The separating step according to the present invention can remove the ingredients which exhibit no superconductivity out of the mixed powder, so that a high-quality oxide superconductor in which the temperature difference between the onset and the offset is small and the offset temperature is high can be obtained.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an explanatory view showing the conventional method for manufacturing an oxide superconductor;
FIG. 2 is a graph showing the resistance-temperature characteristics of the oxide superconductors manufactured by the conventional method and one embodiment of the present invention;
FIG. 3 is an explanatory view showing the method for manufacturing an oxide superconductor according to one embodiment of the present invention;
FIG. 4 is a sectional view schematically showing the state of the mixed powder contained in a container;
FIG. 5 is a schematic diagram illustrating the separating step in one embodiment of the present invention;
FIGS. 6, 7, 8 and 9 are schematic diagrams illustrating the separating steps in other different embod
REFERENCES:
patent: 4743364 (1988-05-01), Kyrazis
patent: 4828685 (1989-05-01), Stephens
Hor et al, "Switching Phenomena . . . Superconductor", Nature, vol. 326, Apr. 1987, p. 669.
Newhouse, "Applied Superconductivity", Sep. 1965, pp. 6-10.
Barsoum et al, "Use Of the Meissner . . . Powders", Applied Physics Letters, vol. 51, No. 23, Dec. 1987, pp. 1954-1956.
Ohara Akinori
Yamada Tadatoshi
Yamamoto Shunji
Fiorilla Christopher A.
Mitsubishi Denki & Kabushiki Kaisha
Silbaugh Jan H.
LandOfFree
Method for separating superconductor powder from nonsuperconduct does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method for separating superconductor powder from nonsuperconduct, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for separating superconductor powder from nonsuperconduct will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2015759