JPH02257529A - Manufacture of oxide superconductor - Google Patents

Abstract

PURPOSE:To enhance the orientation and critical current density of an oxide superconductor by covering a superconducting oxide with a material which exhibits transparency at a melting point higher than that of the oxide, and spinning and crystallizing it with irradiation of laser beam. CONSTITUTION:A rod 1 of Y-Ba-Cu type superconducting oxide is put in a cylindrical body 2 formed of SrTiO3 so that a complex body 3 is formed. The lower portion of the complex body 3 is heated by a heater 4 and is spined to draw out a linear body 5. It is immediately cooled by gas in a cooler 6 and then irradiated with laser beam 7. Since the superconductor is thus covered with a material which exhibits transparency at a fusion point higher than that of the superconducting oxide, only the oxide in a narrow band is immediately melted and solidified by irradiation of laser beam, and a large temperature gradient is achieved. Thus a crystal of high orientation is obtained and a linear body with excellent superconducting properties is obtained.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for producing an oxide superconductor, and particularly a method for producing a linear oxide superconductor having excellent crystal orientation, that is, excellent superconducting properties. Regarding.

[Prior Art] In recent years, the development of oxide superconducting materials has progressed at a remarkable speed, and the use of superconducting materials such as La-based, Y-based, Bl-based, and Tl-based materials is considered to be promising.

However, the superconducting properties of these materials are significantly anisotropic, that is, they are highly dependent on crystal orientation, and simply by molding and sintering raw material powder obtained by conventional synthesis methods, only those with random crystal orientation can be obtained. Therefore, there is a problem that electrical and magnetic properties that reach a practical level cannot be obtained.

As a method to solve the above problem, an attempt has been made to increase crystal orientation by melting an oxide superconducting material and moving this melt relatively in an electric furnace with a temperature gradient to grow crystals. ing.

Furthermore, attempts have been made to improve crystal orientation by forming a floating zone in a superconductor, such as a linear superconductor, and melting and solidifying the superconductor.

[Problem to be solved by the invention] However, in the former melting temperature gradient crystallization method, there is a limit to the setting of the temperature gradient, and it is impossible to form a large gradient in the furnace by heat conduction, so it is difficult to change the crystal orientation. It has the disadvantage that it is difficult to control.

On the other hand, the latter method using a floating zone has the drawback that only a phase that stably crystallizes from the liquid phase can be obtained, and the growth rate thereof is extremely slow at several c to several ms/hr. In particular, in this method, Y-Ba-C
In the case of u-0-based oxides, a fatal drawback is that a Y2BaCu0x phase, which is an insulating material, is produced by melting and recrystallization, but a YBa2Cu30x phase, which is a superconducting material, is not produced.

The present invention has been made to solve the above-mentioned difficulties.
The object of the present invention is to provide a method for manufacturing a linear oxide superconductor with excellent crystal orientation, that is, excellent superconducting properties, using a laser beam.

[Means for Solving the Problems] In order to achieve the above object, the method for producing an oxide superconductor of the present invention provides a method for producing an oxide superconductor that includes, on the outside of an oxide superconductor or a raw material containing an element constituting the oxide superconductor, After disposing a coating layer made of a material that has a higher melting point than the above substance and is transparent to the laser beam used, this is melt-spun to form a linear body, and then the laser beam is applied. It is recrystallized or crystallized by irradiation.

The oxide superconducting material in the present invention is not particularly limited, and for example, La-Ba-Cu-0, La-3r-
Ca-Cu-0 system, Y-Ba-Cu-0 system, B1-9r
-Ca-Cu-0 type oxides, Tl-Ba-Ca-Cu-0 type oxides, and the like can be mentioned.

Further, as the raw material containing the elements constituting the oxide superconducting material, oxides, carbonates, nitrates, metal soaps, etc. containing these elements are used, such as Y-Da-
In the case of Cu-0, Y205, BaCO3, and CuO are used.

Furthermore, T102 is a material that has a higher melting point than superconducting materials and is transparent to laser beams.
(Melting point 1840℃, light transmission range 0.45~Bam)
, 5rTi02 (melting point 2080°C, light transmission range 0.
4-7μm), ^1203 (melting point 2050℃, light transmission range 0.17-6.5pm), MgO5Si02
, Zr02, YSZ (yttrium stabilized zirconium), and other oxides can be used. These materials have translucency to the YAG oscillation wavelength of 1.06 μm. In particular, Zr02 and YSZ have an advantage in that the oxygen ion conductivity increases with the application of voltage, so that it is easy to control the inflow and outflow of oxygen during annealing.

The laser beam in the present invention is A'', YAG.

It is formed by a CW (continuous) laser such as CO2, and is irradiated with multiple lasers so that a symmetrical temperature distribution is formed especially in the cross section perpendicular to the axial direction of the linear body, and the beam diameters overlap each other. It is preferable to do so. For this reason, multiple laser beams are irradiated toward the fiber center at equal angles so as to form a concentric temperature distribution on the fiber having a circular cross section. For example, a laser beam with a beam diameter of about 20 μmφ is used to form a melting zone with a length of about 50 μm, and the linear body (or beam) is heated at 1-10 cm/se.
Move at a speed of about e.

[Effect 1] Since the present invention is coated with a material that has a higher melting point than the superconducting oxide and is transparent, only the internal oxide can be rapidly removed in a very narrow band by laser beam irradiation. Not only can it be melted and solidified, but it can also achieve a very large temperature gradient, and as a result, crystals with very high orientation can be obtained, and linear bodies with excellent superconducting properties can be obtained. Further, lengthening can be easily achieved.

【Example] An embodiment of the present invention will be described below.

The figure is a schematic diagram showing an example of an apparatus used in the method of the present invention.

Weigh out a predetermined amount of yttrium oxide, barium carbonate, and copper oxide powder with a particle size of 5 μlφ so that Y:Ba:Cu = l:2:3, fill it into a rubber vibrator, and store 2 to 3 tons of powder.
CIP treated with /c-, outer diameter 2mm, length 30cm
A rod was formed. On the other hand, by the same method, 5rTI
O1, inner diameter 2.1 ta-φ, outer diameter 4.1 ta-φ,
A cylindrical body 2 having a length of 30 cm was formed, and the above-described temporarily sintered rod 1 was housed inside this cylindrical body. The composite body 3 thus obtained is held vertically, and its lower part is heated by a heater 4.
After heating and spinning at a speed of 10 cm/see, the linear body 5 was drawn out, immediately cooled with gas in a cooler 6, and then irradiated with a laser beam 7 from the outer periphery. Laser beam (YAG laser; wavelength 1.08 μts) Output: 50
01w, using 30 beams with a beam diameter of 20 μmφ, and an outer diameter of 20
The light was irradiated from the outer periphery of the linear body 5 of 0 μ-φ at equal angles. The thus obtained superconducting wire had very good crystal orientation in the axial direction, and its critical current density (Jc) value was 1 G'^lC-. In addition, the Jc of the superconducting wire produced by the floating zone method (small elliptical infrared heating, 1.5 kv) by irradiating the spun linear body with infrared rays is 1 G" to 10' A/c-, and the axial Some ab orientation was observed.

[Effects of the Invention] As described above, according to the method for manufacturing an oxide superconductor of the present invention, only the internal oxide can be recrystallized or crystallized by irradiation with a laser beam, so that high crystallinity can be achieved. This method has extremely high value as a practical method, since it is possible to obtain a linear body with orientation and thus a high critical current density, and also because it is easy to control and the manufacturing speed is high.

[Brief explanation of drawings]

The figure is a schematic diagram showing an embodiment of the method of the invention. 1・・・・・・・・・Rod 2・・・・・・・・・Cylindrical body 5...... Linear body 7・・・・・・・・・Laser beam Representative Patent Attorney Su Yamasa - (1 other person)

Claims (1)

[Claims] (1) On the outside of the oxide superconducting material or the raw material containing the elements constituting the oxide superconducting material, a material that has a higher melting point than the above material and is transparent to the laser beam used is used. 1. A method for producing an oxide superconductor, which comprises disposing a coating layer, melt-spinning the coating layer to form a linear body, and recrystallizing or crystallizing the coating layer by irradiating the coating layer with a laser beam.