JPH0764624B2 - Method for producing oxide superconductor composition - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an oxide superconducting material used in various superconducting application devices and superconducting elements.

(Prior Art) As superconducting materials, various materials such as metal element superconducting materials, compound superconducting materials, and alloy superconducting materials are known. Superconducting materials are used to make electronic devices such as Josephson devices, coils for superconducting magnets, and various sensors.

By the way, the superconducting transition temperature T above the boiling point of liquid nitrogen (77K)
It is known that the Tc of LnBa ₂ Cu ₃ O _7-y having c changes by substituting Cu with a transition metal Al. This
Compounds with arbitrary Tc can be synthesized according to the substitution amount of Al, and expectations for it as a practical material for various sensors are increasing.

(Problems to be Solved by the Invention) LnBa ₂ (Cu _1-x Ga _x ) ₃ O _7-y is an arbitrary Tc depending on the substitution amount of Ga.
However, there is a problem that the critical current density (Jc) is generally low because of its large dependence on the magnetic field. An object of the present invention is to provide a method for producing a superconductor composition that can change Tc, has a small magnetic field dependency, and has a high Jc.

(Means for Solving the Problem) The present invention is LnBa ₂ (Cu _1-x Ga _x ) ₃ O _7-y (where Ln is Y, La, Nd, S
One or more of m, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, 0 <x ≦
0.2) is a method for producing an oxide superconductor, characterized in that the raw materials are adjusted so that the molar ratio of the metal ions is represented by 0.2), and high-pressure oxygen treatment is performed after firing.

(Example) As a starting material, barium carbonate (BaC
O ₃ ), yttrium oxide (Y ₂ O ₃ ), cupric oxide (Cu
O) and gallium oxide (Ga ₂ O ₃ ) are used and weighed respectively.
In YBa ₂ (Cu _1- xGa _x ) ₃ O _7-y , a single-phase composition cannot be obtained in the range of x> 0.2. Next, each of the weighed materials was wet mixed in a ball mill and then calcined at 800 to 850 ° C. This powder was crushed using a mortar, an organic binder was put therein, and the powder was sized and then pressed to prepare a disk having a diameter of 16 mm and a thickness of 1.5 mm. Next, the sample of the composition range of the present invention is 85% in oxygen.
Sintered for 4 hours at a temperature of 0-900 ° C. This was subjected to high-pressure oxygen treatment in oxygen at 100 to 150 atm at a temperature of 300 to 400 ° C for 40 to 50 hours.

The value of y in the composition formula was measured by non-dispersive infrared spectroscopy using the calcined body subjected to high-pressure oxygen treatment, and as a result, -0.1 ≦ y
A value of ≦ 0.1 was shown.

The resistivity was measured by the DC four-terminal method. Gold was attached to the electrodes by a sputtering method, and gold wires were used as leads.

Furthermore, the ratio of the superconducting phase at 4.2K was measured by measuring the AC susceptibility.

The AC susceptibility was measured by putting a sample in a coil and measuring the change in the L component. Change the L component of the sample to the same volume, ΔL at 4.2K of lead of the same shape at 10
It was set to 0, and the ratio of the superconducting phase was calculated. These measurements were performed from room temperature to helium temperature (4.2K).

For example, a composition of YBa ₂ (Cu _0.95 Ga _0.05 ) ₃ O _7-y shows a large magnetic field dependency with respect to a magnetic field of 0.1,1,10 Oe as shown in FIG. However, as shown in Fig. 2, the dependence of the magnetic field is reduced when this is subjected to high-pressure treatment in 100 atm of oxygen.
Tc also rose from 60K to 80K. It was also confirmed that Jc at a temperature lower than Tc by 10 K increased from 500 A / cm ² to 800 A / cm ² .

Also, when Ln is La, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, the same result as Y was obtained.

(Effects of the Invention) As described in the examples, the composition synthesized according to the production method of the present invention has less dependence on the magnetic field than the conventional material, and thus is very practical as a method for producing a superconducting material composition. It is a thing.

[Brief description of drawings]

FIG. 1 is a diagram showing a temperature change of an AC susceptibility of a fired body produced by a conventional manufacturing method. FIG. 2 is a diagram showing a temperature change of the AC susceptibility of the fired body according to the present invention.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Internal reference number FI Technical indication location H01L 39/24 ZAA Z // H01B 12/00 ZAA (72) Inventor Yoshimi Kubo Minato-ku, Tokyo 5-33-1 Shiba Electric Company (72) Inventor Toshio Takada 1 Nishiseuchi-cho, Kitashirakawa, Sakyo-ku, Kyoto City, Kyoto Prefecture (72) Inventor Mikio Takano Uzumasa Yasui-Touramachi, Ukyo-ku, Kyoto City, Kyoto Prefecture 17 (72) Inventor Yasuo Takeda 736-5 Kanonji-cho, Tsu City, Mie Prefecture (56) References Japanese Journal of Applied Physics Vol. 26 No. 5 P. L815 to L817 Japanese Journal of Applied Physics Vol. 26 No. 5 P. L633 to L634 Powder and powder metallurgy Vol. 34 No. 10 P. 537-544 Powder and powder metallurgy Vol. 34 No. 10 P. 601-602

Claims (1)

[Claims] 1. LnBa ₂ (Cu _1-x Ga _x ) ₃ O ₇ (where Ln is Y, La, Nd,
One or more of Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, 0 <x
A method for producing an oxide superconductor composition, which comprises adjusting the raw materials so that the molar ratio of metal ions has a composition represented by ≦ 0.2), firing and then performing high-pressure oxygen treatment.