CS267465B1 - A method for producing a superconducting material - Google Patents

Abstract

Superconducting material based on Mo^+Mc?+Cu 0 ,, where Mo^ + is one Si more and b o d elements of a series of rare earth elements, for example La and Y and Mo”+ is one or more elements of the alkaline earth group, in particular Sr and Ba. The production method according to the invention is based on crystallochemical technology, in which the raw material of the above composition is melted to a temperature of 1,100 to 1,300 C, preferably in an oxidizing environment, after which it is subjected to crystallization, preferably directional, by lowering the temperature.

Description

The invention 30 relates to a process for the production of a superconducting material based on Me ^{3 + Me 2+} Cu O. where 3+, abc ď

Me ^J Jo one or more elements of a number of rare earths, especially La and Y and Me ' ^{- +} is one or more elements of the group of corrosive earths, especially Sr and Ba, while the indices a, b, c, d indicate the relative representation of these elements in the given material.

The known method of producing a superconducting material of this type is based exclusively on ceramic technologies, i.e., grinding, pressing, sintering, which can be repeated in different order so that the resulting material is as homogeneous as possible and contains the highest possible proportion of the desired superconducting phase. Although these ceramic processes have succeeded in achieving interesting results, their preparation is lengthy and the products are difficult to use for practical applications.

The smelting clinics have not yet been used in the production of superconducting materials, since the partial melting of hitherto known superconductors leads to their decomposition and loss of superconducting properties.

Therefore, the possibility of producing these superconducting materials by evaporation or sputtering and subsequent heat treatment is investigated. However, only planar thin films can be prepared in this way.

Said drawbacks of the prior art are eliminated by the method for producing a superconducting material according to the present invention, the principle of which is based on crystal chemical technology, in which the raw material of the above composition is melted at 1,100 to 100 subjected to crystallization preferably in a given direction given by a temperature gradient in the range of 0.1 to 150 ° C / cn. The resulting product can be subjected to a subsequent tempering at a temperature of 600 to 1100 ° C, preferably in an oxidizing medium, in a given temperature gradient in the range of 0.1 to 150 ° C / cm.

The advantage of the method according to the invention is its speed while obtaining a superconducting material of higher parameters and the possibility of obtaining various shapes of materials suitable for use in practical applications.

The process according to the invention was verified on the following examples:

Example 1

Finely ground mixture of Y ₂ ° 3 ' ^{Ba0 and Cu0 in} P ° ^m ^ ^ru g ^Ba 0 2 ^Cu0 l ( ^{melted for} 3 h in oxidizing air at a temperature of 1200 - 50 ° C, after which it was spontaneously cooled to room temperature. was superconducting with a transition to a superconducting state characterized by the temperature Tc (l / 2) = 98 K, where Τ _β (1/2) is half the temperature interval between the temperature of the beginning of the transition of the material to the superconducting state and the zero resistance temperature of the material.

Example 2 The same procedure as in Example 1 was used, except that in a Pt crucible 100 mm long and 3 mm in diameter, the molten feedstock was subjected to directional crystallization in the direction of the crucible axis at a rate in the range of 0.1 to 50 mm / h. in a temperature gradient ranging from 0.1 to 150 ° C / cm. The obtained product was superconducting with a transition to a superconducting state characterized by the temperature T _c (1/2) = 120 K.

The method according to the invention can be used in perspective in wide technical practice, especially in the fields of production, conducting, conversion and accumulation of electric current, use of magnetic fields of extremely high intensities, in transport, medicine.

Claims (4)

Process for the production of superconducting material based on rare earth elements, such as La α Y a Ί + 2+ 3+ Me ^J Me. Cu 0 ,, where Me ^J is one or more bc ď ““ Me is one or more elements of the group of corrosive soils, in particular Sr and Da, the indices a, b, c, d denoting the relative proportion of these elements in the given material, characterized in that the raw material of the above composition melts to a temperature of 1,100 to 1,300 ° C, after which it is subjected to crystallization. 2, The method according to item 1, characterized in that the raw material is melted in an oxidizing medium. 3. The process according to items 1 and 2, characterized in that the crystallization takes place in a given direction given by a temperature gradient in the range of 0.1 to 150 ° C / cm 2. 4. The process according to items 1 to 3, characterized in that the product obtained is subjected to a subsequent tempering at a temperature of 600 to 1100 ° C, preferably in an oxidizing medium, preferably in a given temperature gradient in the range 0.1 to 150 ° C. cm.