Superconductor technology: apparatus – material – process – High temperature – per se – Free metal containing
Reexamination Certificate
1998-12-14
2001-01-09
Kopec, Mark (Department: 1751)
Superconductor technology: apparatus, material, process
High temperature , per se
Free metal containing
C505S126000, C505S781000, C505S785000
Reexamination Certificate
active
06172007
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an oxide superconductor which exhibits excellent superconducting properties such as a high critical current density. Further, the present invention is applicable to, for example, a current lead, magnetic bearing, a magnetic shielding and to a bulk magnet.
2. Description of the Related Art
Hitherto, there has been known a conventional method of manufacturing such a kind of an oxide superconductor (see Japanese Examined Patent Publication No. Hei 7-51463/1995 Official Gazette), by which a RE—Ba—Cu—O oxide superconductor (incidentally, RE is a rare earth element including Y) is manufactured by performing a treatment on a raw material mixture containing a RE compound, Ba compound and a Cu compound (incidentally, this treatment includes at least a burning (or baking) process to be performed in a range of temperatures that are higher than the melting point of such a raw material mixture).
In the case of this conventional manufacturing method, the raw material mixture, in which the RE compound, the Ba compound and the Cu compound are mixed in a predetermined mole ratio, is once melted. Thereafter, the raw material mixture is quenched and solidified. Then, the solidified raw material mixture is pulverized or crushed into fine powder. Subsequently, such powder is heated again to a temperature of a high temperature region in which the powdery mixture partially presents a liquid phase. Thereafter, the mixture is gradually cooled. Thus, a superconducting phase is grown. Furthermore, an oxide superconductor exhibiting a relatively high critical current density can be obtained by performing annealing process in an oxygen atmosphere.
However, in the case of the aforementioned manufacturing method, the coagulation and condensing of the raw materials occur when once melting the raw material mixture for forming a RE—Ba—Cu—O superconductor. Thus, it is necessary for uniformly dispersing the raw materials to crush the raw materials into very fine powder. Moreover, the density of a sample (or specimen), which is melted and recrystallized by using fine raw materials, becomes very high. Thus, the conventional method has problems in that the diffusion velocity of oxygen is low and that an oxygen annealing time is very long.
The present invention is accomplished to solve the aforementioned problems of the prior art.
SUMMARY OF THE INVENTION
Accordingly, an object of the present invention is to provide an oxide superconductor which has superconducting properties and uniform higher critical current density.
Further, another object of the present invention is to provide a simple method of manufacturing such an oxide superconductor at a low cost.
To achieve the foregoing objects, in accordance with an aspect of the present invention, there is provided an oxide superconductor (hereunder sometimes referred to as a first oxide superconductor of the present invention) in which fine particles (or grains) of a RE
2
BaCuO
5
phase (RE is one or more kinds of rare earth elements including Y) are dispersed in a crystal of a REBa
2
Cu
3
O
7−x
phase. In the first oxide superconductor of the present invention, fine voids, each of which has a diameter of 10 to 500 &mgr;m, are dispersed therein.
In accordance with another aspect of the present invention, there is provided an oxide superconductor in which a Re
2(1+q)
Ba
1+r
CuO
5+a
phase to a RE
4(1+q)
Ba
2(1+r)
Cu
2(5+a)
phase are minutely disposed in a RE
1−x
Ba
2+y
Cu
8
O
d
phase (RE signifies one or more kinds of rare earth metal elements including Y), wherein voids each having a diameter of 10 to 500 &mgr;m are minutely disposed in the oxide superconductor, and Ag having a diameter of 0.1 to 100 &mgr;m are disposed therein.
In accordance with another aspect of the present invention, there is provided another oxide superconductor (hereunder sometimes referred to as a second oxide superconductor of the present invention) in which fine particles of a RE
2
BaCuO
5
phase (RE is one or more kinds of rare earth elements including Y) are dispersed in a crystal of a REBa
2
Cu
3
O
7−x
phase. In the second oxide superconductor of the present invention, the density thereof is 5 to 6 g/cm
3
.
In accordance with a further aspect of the present invention, there is provided still another oxide superconductor (hereunder sometimes referred to as a third oxide superconductor of the present invention) in which fine particles of a RE
2
BaCuO
5
phase (RE is one or more kinds of rare earth elements including Y) are dispersed in a crystal of a REBa
2
Cu
3
O
7−x
phase. In the third oxide superconductor of the present invention, fine voids, each of which has a mean particle diameter (or size) of 10 to 500 &mgr;m, are dispersed therein. Moreover, the density thereof is 5 to 6 g/cm
3
.
In the case of an embodiment (hereunder sometimes referred to as a fourth oxide superconductor of the present invention) of the first, second or third oxide superconductor of the present invention), the fourth oxide superconductor of the present invention contains 0.05 to 5 in percent by weight (wt %) of one or more kinds of elements of metals Pt, Pd, Ru, Rh, Ir and Os and compounds thereof.
In the case of an embodiment (hereunder sometimes referred to as a fifth oxide superconductor of the present invention) of the first, second, third or fourth oxide superconductor of the present invention), the fifth oxide superconductor of the present invention contains 1 to 30 wt % of Ag.
In accordance with still another aspect of the present invention, there is provided an oxide-superconductor manufacturing method (hereunder sometimes referred to as a first method of the present invention) of manufacturing a RE—Ba—Cu—O oxide superconductor (RE is one or more kinds of rare earth elements including Y) by performing a treatment, which includes at least a burning process to be performed in a range of temperatures that are higher than the melting point of a raw material mixture containing a RE-compound raw material, Ba-compound raw material and a Cu-compound raw material, on the aforesaid raw material mixture. The first method of the present invention further comprises the step of crushing the aforesaid raw material mixture into particles after the burning thereof, and of establishing the mean particle diameter (or size) of one or all of the aforesaid raw materials as ranging from 50 to 80 &mgr;m.
In the case of an embodiment (hereunder sometimes referred to as a second method of the present invention) of the first method of the present invention, 0.05 to 5 wt % of one or more kinds of elements of metals Pt, Pd, Ru, Rh, Ir and Os and compounds thereof are added to the aforesaid raw material mixture.
In the case of an embodiment (hereunder sometimes referred to as a third method of the present invention) of the first or second method of the present invention, 1 to 30 wt % of Ag is further added to the aforesaid raw material mixture.
When manufacturing a RE—Ba—Cu—O oxide superconductor (RE is one or more kinds of rare earth elements including Y) by performing a treatment, which includes at least a burning process to be performed in a range of temperatures that are higher than the melting point of a raw material mixture containing a RE-compound raw material, Ba-compound raw material and a Cu-compound raw material, on the aforesaid raw material mixture, fine particles of the RE
2
BaCuO
5
phase, which have a mean particle diameter of 1 to 30 &mgr;m or so, are dispersed in a crystal of the REBa
2
Cu
3
O
7−X
phase. Consequently, the critical current can be increased.
Moreover, according to the oxide superconductor manufacturing method of the present invention, the aforesaid raw material mixture is burned and pulverized into particles in such a manner that the mean particle diameter of one or all of the aforesaid raw materials is adjusted to a size in the range from 50 to 80 &mgr;m Thus, the density of each compact (or pellet) is lowered to 4 to 5 g/cm
3
by using such a raw
Haseyama Shuetsu
Kohayashi Shuichi
Yamaguchi Kazuya
Yoshizawa Shuji
Dowa Mining Co. Ltd.
Kopec Mark
Oliff & Berridg,e PLC
LandOfFree
Oxide superconductor does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Oxide superconductor, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Oxide superconductor will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2536893