JPH02257526A - Manufacture of oxide superconductor - Google Patents

Abstract

PURPOSE:To enhance the orientation and critical current density of an oxide superconductor by melting with laser beam a fiber which is spined from a molten body, and then solidifying it. CONSTITUTION:An oxide of e.g. Y-Ba-Cu-O type is stocked in a melting pot 1 and an oxide melted 2 is obtained using a heater 6. The liquid surface 2' of the oxide 2 is pressurized by a gas 7 and a molten body is blown out from a dice 8 and is immediately cooled by gas in a cooler 3, and is then irradiated with laser beam 5. Because fiber spined from the molten body is thus immediately melted and solidified in a very narrow band, a very large temperature gradient is achieved, and thereby a crystal of high orientation is obtained and hence 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, old yarn, and Tl-based materials is considered to be promising.

However, these materials have anisotropy in their superconducting properties, that is, there are significant differences in properties depending on the crystal orientation, and simply molding and sintering the raw material powder obtained by normal synthesis methods only yields materials with random crystal orientation. Therefore, there is a problem in 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, ranging from several marks to several 11111/hr. In particular, in this method, Y-Ba
In the case of -Cu-0 based oxides, a fatal drawback is that the Y2BaCu0x phase, which is an insulating material, is produced by melting and recrystallization, but the YBa2 Cu30x 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 includes melting an oxide superconducting material or a raw material containing an element constituting the oxide superconducting material, The process involves spinning this to form a fiber- or tape-shaped linear body, irradiating the linear body with a laser beam, and rapidly moving the melted zone formed by this irradiation. .

The oxide superconducting material in the present invention is not particularly limited, and includes, for example, La-Ba-Cu-0, La-8r-C
a-Cu-0 series, Y-Ba-Cu-0 series, B1-8r-
Examples include oxides such as Ca-Cu-0 type and Tl-Ba-Ca-Cu-0 type.

In addition, as the raw material containing the elements constituting the oxide superconducting material, oxides, carbonates, nitrates, metal soaps, etc. containing these elements are used; for example, Y-Ba-
In the case of Cu-0, Y2O5, BaC03, and CuO' are used.

The laser beam in the present invention is Ar or 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, so that the beam diameters overlap each other. Irradiation is preferred. 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 μΦ is used to form a melting zone with a length of about 50 μ days, and the linear body (or beam) is heated at 1-10 cIII/see.
Move at a moderate speed.

[Operation] In the present invention, since the amorphous, single crystal, etc. fiber spun from the melt is rapidly melted and solidified in a very narrow band by the laser beam, it is possible to achieve a very large temperature gradient. As a result, crystals with extremely high orientation can be obtained, and linear bodies with excellent superconducting properties can be obtained. Further, lengthening can be easily achieved.

[Example] The figure is a schematic diagram showing an example of an apparatus used in the method of the present invention. In the figure, 1 is a melting crucible, 2 is a molten oxide, 3 is a cooler, 4 is a fiber, and 5 is a laser beam. A Y-Ba-Cu-0 based oxide (Y:Ba:Cu -1:2:3) is placed in the melting crucible 1, and the inside of the crucible is heated to 1200°C or higher using a heater 6 to form an oxide. 2 was melted. The liquid surface 2' of this melt is pressurized by gas 7, and the melt is pumped through the die 8 at the bottom of the crucible by about 10 CII/
See was ejected, and immediately after gas cooling was performed in the cooler 3, the laser beam 5 was irradiated from the outer periphery. Thirty laser beams were used, each having an output of 5ooII1w and a beam diameter of 20μmφ, and were irradiated at equal angles from the outer periphery of the fiber 5 having an outer diameter of 100μmφ.

The axial crystal orientation, critical current density, etc. of the superconducting wire thus obtained are shown in the table below.

As comparative examples, the results of the floating zone method using infrared rays (single elliptical infrared heating, 1,5 K%/cm) and the melting temperature gradient crystallization method using an electric furnace at 30"C/cm are shown in the same table. Ta.

(The following is a blank space) [Effects of the Invention] As described above, according to the method for producing an oxide superconductor of the present invention, a linear body having a high crystal orientation and a high critical current density can be produced. It is extremely valuable as a practical method 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 apparatus used in the method of the present invention. 1... Melting crucible 2... Melting oxide 3... Cooler 4... Fiber 5. ......Laser beam 6...Heater

Claims (2)

[Claims] (1) A step of melting an oxide superconducting material or a raw material containing an element constituting the oxide superconducting material, and spinning this to form a fiber- or tape-like linear body, and applying a laser beam to the linear body. A method for producing an oxide superconductor, comprising irradiating a beam and rapidly moving a molten zone formed by the irradiation. (2) The method for manufacturing an oxide superconductor according to claim 1, wherein a plurality of laser beams are irradiated.