CN1569633A

CN1569633A - Method for preparing MgB2 superconductive material

Info

Publication number: CN1569633A
Application number: CNA2004100179520A
Authority: CN
Inventors: 高召顺; 张义邴
Original assignee: University of Shanghai for Science and Technology
Current assignee: University of Shanghai for Science and Technology
Priority date: 2004-04-27
Filing date: 2004-04-27
Publication date: 2005-01-26
Anticipated expiration: 2024-04-27
Also published as: CN1264749C

Abstract

The invention relates to a process for preparing MgB2 superconducting material which comprises the steps of, grinding B2O3 and Mg powder under the protection of oinert gas, loading the grinded raw material into ceramic crucible, sintering the crucible in vacuum pit furnace, naturally cooling down to room temperature in vacuum or under the inert gas protection status.

Description

MgB2Method for preparing superconductor material

Technical Field

The present invention relates to a preparation method of superconductor material, in particular, it is a MgB₂A method of preparing a superconductor material.

Background

MgB with critical transition temperature of 39K is discovered for the first time in 1 month from 2001₂MgB has been done by scientists in various countries since superconductors₂The synthesis of superconductors has been extensively studied, since up to now MgB has been the sole cause of the problem₂The preparation technology of the film and the block is complex and not completely mature. Application of block material in superconducting strong current field and block materialThe basis for physical Property study, MgB₂The preparation method of the superconductor block is mainly a chemical solid-phase reaction method, and high-purity Mg powder and B powder are used as raw materials and sintered under high pressure. Because of the extremely high volatility and the easy oxidability of Mg, the preparation process is more complex: raw materials need to be wrapped, a sintering furnace device needs to be sealed and pressure-resistant, argon and hydrogen mixed high-pressure gas is introduced in the sintering process, and particularly, high-purity B is difficult to obtain and expensive. Thus, the existing preparation techniques present obstacles to large-scale production and its widespread use.

Disclosure of Invention

The invention aims to provide MgB₂Method for producing superconductor, using inexpensive powder B₂O₃And Mg powder as raw materials, and the crucible self-sealing technology is utilized to achieve the purposes of simplifying the preparation process and saving the production cost.

The reaction mechanism of the method is as follows:

according to the reaction mechanism, the invention adopts the following technical scheme:

MgB₂A process for the preparation of a superconductor material, characterized in that the process is carried out as B₂O₃And Mg powder as raw materials, and the specific steps are as follows:

a. b is to be₂O₃Grinding the Mg powder and the Mg powder according to the molar ratio of 1: 4 under the protection of inert gas to uniformly mix the Mg powder and the Mg powder;

b. placing the ground raw materials into a ceramic crucible, covering with a ceramic inner cover, and scattering appropriate amount of Mg and B along the edge of the inner cover₂O₃Mixing the powder to form a barrier between the raw material and the outside air;

c. putting the crucible into a vacuum sintering furnace or a heating furnace filled with inert protective gas (nitrogen, argon and the like) for sintering;

d. the sintering is carried out according to the following steps: firstly heating to 400 ℃, preserving the heat for 0.5-2 hours, then heating to 600-650 DEG CThe temperature is kept for 0.5-2 hours, then is raised to 800-900 ℃ and kept for 1 ℃2 hours, finally naturally cooling to room temperature in vacuum or under the protection of inert gas to obtain MgB₂A superconductor material.

In the process of the invention, the purpose of the 400 ℃ hold is to let Mg and B start to melt₂O₃Fully mixing; the purpose of heat preservation at 600-650 ℃ is to ensure that B is allowed to reach the melting point of Mg₂O₃Can fully react with Mg to reduce the volatilization of Mg; the heat preservation is carried out at 800-900 ℃ so as to ensure that MgB is kept₂The grain growth is as largeas possible.

Compared with the prior art, the method of the invention has the following obvious characteristics and remarkable progress: the method uses cheap powder B₂O₃Instead of expensive B, the MgB is obtained by solid-phase replacement reaction through reaction with powdery Mg and crucible self-sealing technology₂Mixed with MgO, thus simplifying MgB₂The preparation process of the superconductor reduces the requirement of a reaction device and greatly saves MgB₂The production cost of superconductors. The zero resistance, the magnetic susceptibility and the X-Ray measurement prove that the MgB prepared by the method of the invention₂The superconductor has good superconducting characteristics, and the superconducting transition temperature of the superconductor is higher than 37K.

Detailed Description

The first embodiment is as follows: the specific process steps of the embodiment are as follows:

1. mixing 6.96 g of B₂O₃And 9.72 g of Mg powder, and grinding the mixture under the protection of nitrogen to be uniformly mixed;

2. placing the ground raw materials into a ceramic crucible, covering with a ceramic inner cover, and scattering appropriate amount of Mg and B along the edge of the inner cover₂O₃Mixing the powder to form a barrier between the raw material and the outside air;

3. putting the crucible into a vacuum sintering furnace for sintering;

4. the sintering is carried out according to the following steps: firstly heating to 400 ℃ and preserving heat for 1 hour, then heating to 600 ℃ and preserving heat for 1 hour, then heating to 800 ℃ and preserving heat for 2 hours, and finally naturally cooling to room temperature in a vacuum stateTo obtain MgB₂A superconductor;

the MgB prepared in this example was demonstrated by standard four-lead resistance measurements, susceptibility measurements and X-Ray measurements₂The superconducting material has good superconducting performance, the critical transition temperature is higher than 37K, and the superconducting phase is MgB₂。

Claims

1. MgB₂A process for the preparation of a superconductor material, characterized in that the process is carried out as B₂O₃And Mg powder as raw materials, and the specific steps are as follows:

d. the sintering is carried out according to the following steps: firstly heating to 400 ℃ and preserving heat for 0.5-2 hours, then heating to 600-650 ℃ and preserving heat for 0.5-2 hours, then heating to 800-900 ℃ and preserving heat for 1-2 hours, and finally naturally cooling to room temperature in vacuum or under the protection of inert gas to obtain MgB₂A superconductor material.