JP2913996B2 - Iodine-inserted oxide superconductor and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oxide superconducting material used for various superconducting devices and superconducting elements.

[0002]

2. Description of the Related Art At present, as a superconducting material, a metal / alloy superconducting material, a compound superconducting material and the like have already been put to practical use. Superconducting materials are used to make coils for superconducting magnets and electronic devices such as Josephson devices, especially for SQUIDs and precision measurements that utilize the high sensitivity, high accuracy, and low noise of Josephson junctions. In addition to the application of, it is expected to be applied to electronic computers that focus on the high-speed response and low power consumption of Josephson junctions. Considering the application of superconducting material, its superconducting transition temperature (Tc)
Should be as high as possible. Metallic / alloy-based superconducting materials and compound superconducting materials must use expensive and rare liquid helium as a refrigerant, which is one of the factors that hinders the application of these superconductors to a wide range of fields. I have. In this respect, the copper oxide-based superconductor is far superior to the conventional superconductor, and has a La-Tc of 30 K.
Since the discovery of Ba-Cu-O-based oxide superconductor, 90K-class Ba-Y-Cu-O-based and 110K-class Bi-Sr-C
a-Cu-O system, Tl-Ba-Ca-Cu of 120K class
-O system and the like have been discovered one after another. The discovery of a material having a Tc far above the temperature of liquid nitrogen has further increased expectations for a practical material.

[0003]

The thallium-based superconductor has the highest Tc at present and is a substance expected to be put to practical use. However, in its application, high T
c, high critical current density (Jc), high critical magnetic field (B
It is desirable to have c). Generally, the oxide superconductor is T
Even when c is high, Jc and Bc are low, so that application in a large current and use under a strong magnetic field have been limited. In view of such a conventional situation, an object of the present invention is to provide a superconductor having an even higher Jc and a method of manufacturing the same using a thallium-based oxide superconductor having a high Tc.

[0004]

SUMMARY OF THE INVENTION The present invention provides an ITl ₂ Ba ₂
(In the formula, n 1, 2, 3 or _{4.) Ca n-1 Cu} n O 4 + 2n iodine inserted thallium based oxide superconductor, characterized by being represented by. The manufacturing method of a solid (wherein, n 1, 2, 3 or 4.) Iodine and _{Tl 2 Ba 2 Ca n-1} Cu n O 4 + 2n thallium based oxide superconductor represented by The body is mixed and heat treated or Tl ₂ Ba ₂ Ca
_{n-1 Cu n O 4 +} 2n ( wherein, n 1, 2, 3 or 4.) or immersed in an organic solvent prepared by dissolving iodine thallium based oxide superconductor represented by, or Tl ₂ Ba ₂ Ca
(In the formula, n 1, 2, 3 or 4 in _{which.) n-1 Cu n O} 4 + 2n , characterized in that placed in the iodine in the gas sublimed thallium-based oxide represented by superconductors .

[0005]

[Action] _{Tl 2 Ba 2 Ca n-1} Cu n O 4 + 2n (n = 1,2,
3,4) is the highest T for each compound with n = 1,2,3,4.
c becomes 85K, 110K, 125K, and 115K. When these compounds are ceramics, Jc at 77K is
100 A / cm ² , 450 A / cm ² , 600 A / c respectively
m ² , 500 A / cm ² . However thallium-based _{oxide, Tl 2 Ba 2 Ca n-} 1 Cu n O 4 + 2n (n = 1,2,3,
4) a material obtained by heat treatment for 5 hours at mixing 300 ° C. and solid iodine, the results of the analysis by powder X-ray diffraction, ITL ₂ B
a ₂ is represented by _{Ca n-1 Cu n O 4} + 2n (n = 1,2,3,4), it is confirmed a compound in which iodine is inserted between the surface of the thallium and oxygen, further Tc Changes little, but Jc is 170 A / cm ² and 650 A / c, respectively.
m ² , 900 A / cm ² and 700 A / cm ² were confirmed. In the synthesis of an iodine-inserted thallium-based oxide superconductor, the same compound is obtained from powder X-ray diffraction when the thallium-based oxide is immersed in an alcohol solution in which iodine is dissolved, and when the thallium-based oxide is placed in a sublimated iodine gas. Was obtained, and it was confirmed that the compound had a high Jc comparable to that of the case of synthesis from solid iodine.

[0006]

EXAMPLES Examples of the present invention will now be described with reference to Tl ₂ Ba _2.
A specific description will be given using Ca ₂ Cu ₃ O ₁₀ as an example. Example 1 Tl ₂ Ba ₂ Ca synthesized according to an ordinary oxide synthesis method
_A mixture of ₂ Cu ₃ O ₁₀ powder and a mixture of I ₂ weighed so as to have a ratio of ITl ₂ Ba ₂ Ca ₂ Cu ₃ O ₁₀ is mixed and sealed in quartz glass, followed by heat treatment at 300 ° C. for 5 hours. Thus, an iodine-inserted thallium-based superconductor was obtained (solid method).

Example 2 A Tl ₂ Ba ₂ Ca ₂ Cu ₃ O ₁₀ powder or single crystal was immersed in an alcohol solution of iodine for 24 hours to obtain an iodine-inserted thallium-based superconductor (liquid method).

Example 3 Tl ₂ Ba ₂ Ca ₂ Cu ₃ O ₁₀ powder or single crystal is put at one end and I ₂ is put at the other end, vacuum sealed in quartz glass, and the I ₂ side is heated. As a result, an iodine-inserted thallium-based superconductor was obtained by generating sublimated iodine gas (gas method).

The synthesis sample was confirmed by powder X-ray diffraction and 4-axis single crystal X-ray diffraction. Evaluation of superconducting properties is based on SKU
The magnetic susceptibility was measured using an ID magnetometer and a normal DC four-terminal method was used. Jc was determined by a DC four-terminal method using a current when a voltage of 0.1 μV or more was generated between the voltage terminals at 77 K and zero magnetic field. Table 1 to Table _{4 Tl 2 Ba 2 Ca n-} 1 Cu n O 4 + 2n (n = 1,2,3,4)
The Tc and Jc before and after performing the iodine insertion reaction of each compound are shown. The iodine-inserted thallium-based superconductor has a T
Although c hardly changes, it is confirmed that it has a high Jc.

[0010]

[Table 1]

[0011]

[Table 2]

[0012]

[Table 3]

[0013]

[Table 4]

[0014]

As described above, the iodine-inserted thallium-based superconductor of the present invention is extremely useful for industrial use as a material having high Tc and Jc.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) C01G 15/00 C01G 1/00 H01B 12/00 ZAA CA (STN) REGISTRY (STN)

Claims (4)

(57) [Claims] [Claim 1] ITL (wherein, n 1, 2, 3 or _{4.) 2 Ba 2 Ca n} -1 Cu n O 4 + 2n iodine inserted thallium-based oxide, which is characterized by being represented by Superconductor. 2. A method for producing a compound according to claim 1, solid iodine and _{Tl 2 Ba 2 Ca n-1} Cu n O 4 + 2n ( wherein, n is 1, 2, 3 or 4 A method for producing an iodine-inserted thallium-based oxide superconductor, comprising mixing and heat-treating the thallium-based oxide superconductor represented by the formula (1). 3. A process according to claim 1 a process for the preparation of a compound _{according, Tl 2 Ba 2 Ca n-} 1 Cu n O 4 + 2n ( wherein, n 1,
2, 3 or 4. A method for producing an iodine-inserted thallium-based oxide superconductor, comprising immersing the thallium-based oxide superconductor represented by the formula (1) in an organic solvent in which iodine is dissolved. 4. The method of claim 1 a process for the preparation of a compound _{according, Tl 2 Ba 2 Ca n-} 1 Cu n O 4 + 2n ( wherein, n 1,
2, 3 or 4. A method for producing an iodine-inserted thallium-based oxide superconductor, comprising placing the thallium-based oxide superconductor represented by the formula (1) in sublimated iodine gas.