JPH0764622B2 - 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 material magnets, and various sensors.

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

(Problem to be Solved by the _{Invention) LnBa 2 (Cu 1-x} Zn x) 3 O 7-y is any substitution of Zn Tc
However, there is a problem that the critical current density (Jc) is generally low because of its large dependence on the magnetic field.

Therefore, it is an object of the present invention to provide a method for producing a superconducting 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 Zn _x ) ₃ O _7-y (where Ln is Y, La, Nd, S
m, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu or more) and the composition of the oxide superconductor (where 0 <x≤0.1, 0.1≤y≤0.
According to 2), the raw material is adjusted so that the metal ion has a molar ratio of the above composition formula, and after firing, high-pressure oxygen treatment is carried out, which is a method for producing an oxide superconductor.

(Example) As a starting material, barium carbonate (BaC
O ₃ ), yttrium oxide (Y ₂ O ₃ ), cupric oxide (Cu
O) and zinc oxide (ZnO), and weigh each. YB
In a ₂ (Cu _1-x Zn _x ) ₃ O _7-y , a single phase composition cannot be obtained in the range of x> 0.1. 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 850-9 in oxygen.
Sintered at a temperature of 00 ° C for 4 hours. 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 a fired body that had been subjected to high-pressure oxygen treatment. As a result, 0.1 ≦ y ≦
A value of 0.2 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. The change in the L component of the sample was adjusted to the correct ΔL at 4.2K for lead of the same volume and shape, 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 Zn _0.05 ) ₃ O _7-y shows a large magnetic field dependence on a magnetic field of 0.1,1,10 Oe as shown in FIG. However, as shown in Fig. 2, the high-pressure treatment of this in oxygen at 100 atm reduced the magnetic field dependence, and the Jc at a temperature 10 K lower than Tc was 300 A / cm ² to 600 A / cm ²
It was confirmed that

Also, when Ln is La, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tw, 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. is there.

[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 Shiba 5-33-1 NIPPON ELECTRIC CO., LTD. (72) Inventor Mikio Takano 17 Uzumaya Yasui Touramachi, Ukyo-ku, Kyoto City, Kyoto Prefecture (72) Inventor Yasuo Takeda Kannonji Town, Tsu City, Mie Prefecture 736-5 (72) Inventor Toshio Takada 1 Nishise no Uchimachi, Kitashirakawa, Sakyo-ku, Kyoto City, Kyoto 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 Japanese Journal of Applied Physics Vol. 26 No. 4 P. L337 to L338 Physical Review B Vol. 33 No. 16 P. 8782-8784 Powder and powder metallurgy Vol. 34, No. 10, P. 601-602

Claims (1)

[Claims] 1. LnBa ₂ (Cu _1-x Zn _x ) ₃ O _7-y (where Ln is Y, La, N
d, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu or more) and the composition (where 0 <x ≤ 0.01, 0.1 ≤ y ≤ 0.2) molar ratio of metal ions A raw material is adjusted so that the above conditions are obtained, and after firing, high-pressure oxygen treatment is performed, and a method for producing an oxide superconductor.