JPH0764623B2 - 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 Tc of LnBa ₂ Cu ₃ O _7-y having c changes by substituting the transition metal Ni for Cu. This
Compounds with arbitrary Tc can be synthesized according to the substitution amount of Ni, 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 Ni _x ) ₃ O _7-y is an arbitrary Tc depending on the substitution amount of Ni.
However, there is a problem that the critical current density (Jc) is generally low because it has a large dependence on the magnetic field.

Therefore, an object of the present invention is to provide a method for producing a superconducting composition that can change Tc, has a small magnetic field dependency, and has a high Jc.

(SUMMARY for a) the invention _{LnBa 2 (Cu 1-x Ni} 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 nickel oxide (NiO) are used and weighed respectively. In YBa ₂ (Cu _1- xNi _x ) ₃ O _7-y , a single-phase composition cannot be obtained when 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 in oxygen.
Sintered at a temperature of ~ 900 ° 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. 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 Ni _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 high-pressure treatment of this in oxygen at 100 atm reduces the magnetic field dependence, and Jc at a temperature 10 K lower than Tc is 500 A / cm ² to 800 A / cm ²
It was confirmed that

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. ..

[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. 5 P. L774 to L776 Japanese Journal of Applied Physics Vol. 26 No. 4 P. L337 to L338 Powder and powder metallurgy Vol. 34, No. 10, P. 601-602

Claims (1)

[Claims] 1. LnBa ₂ (Cu _1-x Ni _x ) ₃ O _7-y (where Ln is Y, La, N
d, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu) and the composition (where 0 <x ≦ 0.1, 0.1 ≦ y ≦ 0.2) of the metal ion molar ratio After adjusting the raw materials so that
A method for producing an oxide superconductor, which comprises performing high-pressure oxygen treatment.