The method of obtaining high temperature superconducting material


C04B35C04B101 -

 

(57) Abstract:

The invention relates to a method for producing a layered high pressure phases of the composition of Sr1-xZnxCuO2(Zn Pr, Nd), which can be used in the energy sector, various electronic devices, measuring and computing techniques for high-temperature superconducting material with Twith45 K. the invention: the proposed method for high-temperature superconducting material based on complex metal oxide includes a mixture of initial components and subsequent thermobaric treatment of the mixture placed in the container, the walls of which are covered with a layer of insulating material, as initial components used cuprite of the respective metals, and as an insulating material used copper foil. The method allows to obtain high-temperature superconducting material with a transition temperature to the superconducting state Twith45 To and content of the superconducting phase 60%. Moreover, enables considerable simplification and cheapening of the process due to the lack of stage heat treatment of the source components and the use of copper foil. The total time of receipt of the Mat is of the composition of Sr1-xZnxCuO2(Zn Pr, Nd), which can be used in the energy sector, various electronic devices, measuring and computing techniques for high-temperature superconducting material with Twith45 K.

Known nitrate method of obtaining high temperature superconducting material composition of Sr1-xZnxCuO2(0 x 0,15; Zn Pr, Nd), in which the required amount of strontium carbonate SrCO3and oxides CuO and Zn2O3dissolved in concentrated nitric acid. The precipitate is evaporated to dryness and calcined at 600oC 4 h and then at 925oC for 12-16 h of the Intermediate product is placed in the container, the inner walls of which are insulated by a layer of foil of platinum or gold and is subjected to a pressure treatment at a pressure of 25 kbar and a temperature of 1000oC for 30 min in the apparatus type "belt". According to x-ray and magnetic measurements, the resulting sample contains from 6 to 24% of a superconducting phase with a transition temperature to the superconducting state Twith40 K [1]

The disadvantages of the method include the difficulty of obtaining due to the use of highly aggressive chemical compounds concentrated nitric acid is receiving SSA, which is 16,5-20,5 PM Disadvantage of this method is also negligible content (6-24%) of the superconducting phase.

Also known carbonate method of obtaining high temperature superconducting material composition of Sr1-xZnxCuO2(where Zn Pr, Nd; 0 x 0,15). The calculated amount of strontium carbonate SrCO3and oxides CuO and Zn2O3mixed and calcined at a temperature of 980oC 48 hours Intermediate product is placed in the container, the inner walls of which are insulated by a layer of foil of platinum or gold, and is treated under a pressure of 30 to 60 kbar and a temperature of 900-1300oC for 5-90 minutes as a result of the superconducting material of the above composition with a transition temperature Twith35-40 To and content of the HTSC phase from 2.5 to 25% [2]

The disadvantages of the method are its long duration ( 48-49,5 h), due to the need of preliminary roasting of the original components, and low process superconducting phase.

Thus, the authors goal was to simplify and shorten the process of obtaining material composition of Sr1-xZnxCuO2with possibly a high content of superconducting phase.

Postavlennom metals by mixing the starting components and the subsequent temperature treatment of the mixture, placed in the container, the walls of which are covered with insulating material, as initial components used cuprite of the respective metals, and as an insulating material of the walls of the container, use the copper foil.

Currently, out of scientific-technical and patent literature is not a method of obtaining high temperature superconducting material based on complex oxides by temperature treatment in the container, the walls of which are insulated with a layer of copper foil, using as initial components of Kopitov of the respective metals.

When using the known nitrate or carbonate technology product, which is subjected to temperature treatment is a mixture of the composition: phase low pressure SrCuO2(70-80%); double perovskite Nd2SrCu2O6, Sr2CuO3Nd2CuO4and CuO. It is a double perovskite is the main impurity, preventing the formation of high pressure phase composition of Sr1-xZnxCuO2that causes the superconducting properties of the material. Using the proposed method Kopitov respective metals allows along snych impurities, thereby providing a higher percentage of receiving the high-pressure phases. The best result obtained using copper foil, which in this case plays the role not only of insulating material, but also, apparently, takes an active part in the chemical reaction, absorbing oxygen and supplying monovalent copper.

The proposed method consists in the following. The calculated amount of cuprite strontium SrCuO2and cuprite rare earth element ZnCuO2where Zn Nd, Pr, thoroughly mixed in a mortar. Then this mechanical mixture is placed in a pyrophyllite container with graphite heater, the inner walls of which are insulated with a layer of copper foil. The container with the sample is placed in a block-matrix type "toroid" and is exposed to high pressure 35 to 40 kbar and temperatures of 700-800oC in the press TO-A for 30-40 minutes and Then the sample is removed from the container, free from copper foil. The sample examined by chemical and x-ray analyses. Volume fraction of the superconducting phase and the transition temperature in HTS status is determined by the coil inductance, calibrated at a frequency of 1 kHz.

Example 1. Mix 0,161 ect is treated under a pressure of 35 kbar and a temperature of 700oC for 40 min in the high-pressure chamber of the type "toroid" (press UP-A, useful volume of the chamber 24 mm3with the use of insulating strip of copper foil. According to x-ray and magnetic measurements, the sample obtained is a superconductor composition of Sr0,88Nd0,12CuO2with lattice parameters a 3,935 , c 3,413 and the transition temperature to the superconducting state Twith45 K. the Fraction of superconducting phase for it is Cs60%

Example 2. Mix of) 0.157 g of cuprite strontium SrCuO2, 0,038 g cuprite praseodymium PrCuO2. Receive material as in example 1, but is treated under a pressure of 40 kbar and a temperature of 800oC for 30 minutes Get the superconductor Sr0,84Pr0,16CuO2with lattice parameters a 3,926 , c 3,429 and the transition temperature Twith43 K. the Fraction of superconducting phase Cs60%

Thus, the proposed method allows to obtain the material composition of Sr1-xZnxCuO2where Zn Nd, Pr, 0 x 0,16 content superconducting phase 60% And achieved a significant simplification and cheapening of the process due to the lack of stage heat treatment of the source components and the use of copper foil. The total time of receipt is reduced on the/SUB>-xLnxCuO2,

where Ln Pr, Nd;

0 x 0,15,

by mixing the starting components and the subsequent temperature treatment of the mixture placed in the container, the walls of which are covered with a layer of insulating material, characterized in that the starting components used cuprite of the respective metals, and as an insulating material used copper foil.

 

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