CN101319380B

CN101319380B - Method for rare earth 242 phase control component for growing superconducting block material

Info

Publication number: CN101319380B
Application number: CN2008100374184A
Authority: CN
Inventors: 姚忻; 孙立杰; 黄宜斌; 程玲
Original assignee: Shanghai Jiaotong University
Current assignee: Shanghai Jiaotong University
Priority date: 2008-05-15
Filing date: 2008-05-15
Publication date: 2011-04-20
Anticipated expiration: 2028-05-15
Also published as: CN101319380A

Abstract

The invention relates to a method for growing a superconducting bulk material by utilizing rare earth 242 phase to control the composition. A precursor is added with light rare earth 242(LRE2Ba4Cu2O9, wherein, LRE is Nd and Sm, etc.) phase powder to control the composition. The ground and sintered LRE123 and LRE242 powder are mixed and ground according to a certain ratio and are pressed into the precursor; the corresponding seed crystal is put on the top part of the precursor, and the LRE-BCO bulk material is prepared by a melt textured method. In the method, the barium-rich rare earth 242 phase powder is utilized because the fused mass composition can be adjusted in a high temperature melting state, thereby effectively suppressing the substitution situation of light rare earth elements and barium elements in the peritectic reaction process, increasing the superconducting transformation temperature of the prepared light rare earth BCO superconductor and improving other performances of the prepared light rare earth BCO superconductor.

Description

Rare earth 242 is controlled the method for component growth superconducting block material mutually

Technical field

The present invention relates to a kind of light rare earths 242 and control the method for component growth superconducting block material mutually, particularly a kind of light rare earths 242 (LRE of the rich barium that in presoma, mixes ₂Ba ₄Cu ₂O ₉, LRE242, wherein light rare earths mainly comprises shirt and elements such as neodymium) and non-superconducting controls bath component mutually, is implemented in the method for growing high-performance light rare earths barium copper oxide superconducting block material in the air.

Background technology

Melting texture method (MTG) is generally believed it is a kind of preparation barium copper oxygen high-temperature superconductor block preparation methods that has potentiality.This class superconduction bulk material has many potential to use, as can be used for aspects such as magnetic suspension force, magnetic bearing, flywheel energy storage and permanent magnet.Therefore, at application the requirement of bulk is generally and has bigger size, higher superconducting transition temperature (T _c) and higher after the match outside critical current density (J _c).It is found that under study for action, compare with traditional yttrium barium copper oxide (YBCO) superconductor, light rare earths barium copper oxygen (LRE-BCO) superconductor, mainly comprise Nd-Ba-Cu oxygen (NdBCO) and samarium barium copper oxygen (SmBCO) superconductor, has more excellent flux pinning ability, higher critical magnetic field strength and the critical current density under High-Field.In addition, because neodymium and samarium have the high characteristic of solubleness in melt, therefore can have the higher speed of growth when this two classes superconductive block of growth, this is more favourable for preparation large volume bulk.But in melting texture growing SmBCO and the NdBCO bulk process, because the Nd atom, the Sm atom is similar with the atomic radius of Ba atom in air, substituting of rare earth atom and barium atom very easily occur, forms Sm (perhaps Nd) _1+xBa _2-xCu ₃O ₇Solid solution, the appearance of this Solid solution has very adverse influence for the superconducting transition temperature and the performance of block materials.In order to address this problem, there is study group to propose in process of growth, to adopt the method for low oxygen partial pressure.The environment of hypoxemia can reduce the alternative ratio of element down, can effectively reduce the formation of Solid solution.But this method required equipment is relatively more expensive, the more complicated that operates, and also under hypoxic atmosphere, the speed of growth of bulk also can be affected and reduce.Comparatively speaking, adopt the method for component control not only can reach the purpose that suppresses the Solid solution generation equally, and because growth can be carried out in air, bulk can have the speed of growth faster.Realize the component control of bulk, generally need in preparation presoma process, in the RE123 superconducting phase, mix a certain proportion of second phase with particular components ratio.By this second component (ratio that for example in SmBCO and NdBCO preparation process, needs to improve the ratio of Ba: Cu and reduce RE: Ba) of coming control growing melt during the stage with the reaction of melt at high temperature, suppress to substitute between element and purpose that Solid solution forms to reach.Compare the atmosphere control method, component control method technology is fairly simple, and operation is also than being easier to, and is less demanding to experimental situation, therefore more is applicable to the batch preparations of block materials.

Summary of the invention

The objective of the invention is at the deficiencies in the prior art, provide a kind of light rare earths 242 to control the method for component growth superconducting block material mutually, be implemented in the big single domain of growing fast in the air, high performance LRE-BCO superconduction bulk material.

For realizing such purpose, in technical scheme of the present invention, used a kind of LRE242 phase powder with the preparation of conventional sintering method.LRE242 second with a kind of rich barium when the preparation presoma sneaks in the LRE123 powder mutually, by the effect of LRE242 phase and melt at high temperature, adjusts the component in the process of growth melt, and what occur between LRE atom that inhibition may occur and the Ba atom substitutes.

Compared with the LRE211 non-superconducting phase that occurs in the general LRE123 superconductive block growth, LRE242 has the ratio of the ratio of higher Ba: Cu and lower LRE: Ba mutually.At high temperature LRE242 in melt can and melt react and decompose.When entering the peritectoid growth phase, certain rising appears in the ratio regular meeting of the barium element in the melt, forms the environment of a rich barium, and this moment, therefore the ratio regular meeting of LRE and Ba reduced.Light rare earths is suppressed the alternative meeting of barium element in this case, thereby can not form the LRE123 Solid solution in the Peritectic Reaction process, and what make final acquisition is exactly the LRE123 superconductive block.

Realize this class growth, the LRE123 and the LRE242 powder mixes that at first will will sinter phase according to the ratio of LRE123+ (10～30) mol%LRE242 in advance into are carried out the component batching together, after being pressed into the presoma sheet, put corresponding seed crystal material at its top, obtain the accurate single domain block materials of LRE-BCO by the heat temperature raising program.

Method concrete steps of the present invention are as follows:

1, according to LRE: Ba: Cu=1: 2: 3 and LRE: Ba: Cu=2: 4: 2 ratio is with LRE ₂O ₃, BaCO ₃, the CuO powder mixes becomes forerunner's powder of LRE123 and LRE242.

2, after grinding two kinds of forerunner's powder evenly, LRE242 810 ℃ of left and right sides sintering 12 hours under nitrogen environment, LRE123 900 ℃ of left and right sides sintering 48 hours in air.And then grinding, sintering, this process repeats 3 times altogether, to obtain the LRE123 and the LRE242 powder of pure phase.

3, the LRE123 powder and the LRE242 powder that obtain behind the sintering is even by the mixed of LRE123+ (10～30) mol%LRE242, be pressed into the presoma sheet, and put seed crystal at the top, be used for control growing orientation.

4, the presoma sheet is placed on the MgO single crystalline substrate, whole system is put into tightness system.

5, be warming up to the following 20-50 of peritectic melting temperature ℃ of LRE-BCO in 2 hours, be incubated 1 hour; Continue heating, be warming up to above 30 ± 5 ℃ of peritectic temperature, and be incubated 1.5 hours in 2 hours.

6, temperature is reduced to the Peritectic Reaction temperature in 15 minutes, with per hour 0.5 ℃ speed cooling 20-40 hour, quenching at last makes superconduction bulk material then.

LRE242 described in the present invention (wherein LRE mainly comprises elements such as Sm, Nd) is the LRE by the rich barium of agglomerating method synthetic under the nitrogen environment ₂Ba ₄Cu ₂O ₉Phase.

The present invention adopts the component control method LRE-BCO superconductive block of growing, and a kind of new LRE242 is incorporated in the melting texture growing process of LRE123 bulk mutually.The LRE242 of rich barium can adjust bath component under high temperature fused state, the light rare earths that occurs in effective inhibition Peritectic Reaction process and the alternative case of barium element, prevent the formation of light rare earths barium copper oxygen Solid solution, improve air superconducting transition temperature and other performance of the light rare earths Ba-Cu-O superconducting body of preparation down.

Advantage of the present invention is: do not introduce other element impurity in (1) process of growth, the preparation of superconductive block is not had a negative impact; (2) need not the special atmosphere environment, technology is simple, and is easy to operate; (3) light rare earths barium copper oxygen can have the higher speed of growth under air ambient, is applicable to that therefore preparation has the high-performance high-temperature superconductor LRE-BCO block materials of big one-domain structure.

Embodiment

Below in conjunction with specific embodiment technical scheme of the present invention is further described.Following examples do not constitute limitation of the invention.

Embodiment 1: melting texture growing samarium barium copper oxygen block materials after Sm242 and the Sm123 powder mixes

1, uses BaCO ₃, CuO and Sm ₂O ₃Powder is prepared original powder according to the component ratio of Sm123 and Sm242.

2, original powder is fully ground evenly, the Sm123 powder is 900 ℃ of left and right sides sintering 48 hours, Sm242 810 ℃ of following sintering 12 hours under nitrogen; For guaranteeing finally to obtain less Sm123 of particle and Sm242 pure phase, with powder regrinding, the sintering behind the sintering, same process is triplicate altogether.

3, the pure phase powder that obtains is prepared burden according to Sm123+ (10～30) mol%Sm242 component, powder compression ground behind the sintering is become The circular presoma sheet of 20 * 10mm, the top is placed seed crystal and is controlled orientation.

4, the presoma sheet that presses in the step 3 is placed on the MgO single crystalline substrate, whole system is put into tightness system.

5, be warming up to 950 ℃ in 2 hours, be incubated 1 hour; Continue heating, be warming up to 1090 ℃ in 2 hours, be incubated 2 hours.

6, in 15 minutes temperature is reduced to 1060 ℃, with per hour 0.5 ℃ speed cooling 30 hours, quenching at last makes superconduction Sm123 block materials then.

Embodiment 2: melting texture growing Nd-Ba-Cu oxygen block materials after Nd242 and the Nd123 powder mixes

1, uses BaCO ₃, CuO and Nd ₂O ₃Powder is prepared original powder according to the component ratio of Nd123 and Nd242.

2, original powder is fully ground evenly, the Nd123 powder is 900 ℃ of left and right sides sintering 48 hours, Nd242 810 ℃ of following sintering 12 hours under nitrogen; For guaranteeing finally to obtain less Nd123 of particle and Nd242 pure phase, with powder regrinding, the sintering behind the sintering, same process is triplicate altogether.

3, the pure phase powder that obtains is prepared burden according to Nd123+ (10～30) mol%Nd242 component, powder compression ground behind the sintering is become

The circular presoma sheet of 20 * 10mm, the top is placed seed crystal and is controlled orientation.

5, be warming up to 950 ℃ in 2 hours, be incubated 1 hour; Continue heating, be warming up to 1130 ℃ in 2 hours, be incubated 2 hours.

6, in 15 minutes temperature is reduced to 1090 ℃, with per hour 0.5 ℃ speed cooling 30 hours, quenching at last makes superconduction Nd123 block materials then.

Claims

1. a rare earth 242 is controlled the method for component growth superconducting block material mutually, it is characterized in that comprising the steps:

1) according to LRE: Ba: Cu=1: 2: 3 and LRE: Ba: Cu=2: 4: 2 ratio is with LRE ₂O ₃, BaCO ₃, the CuO powder mixes becomes forerunner's powder of LRE123 and LRE242;

2) forerunner's powder is through after grinding, LRE123 forerunner's powder 900 ℃ of following sintering 48 hours under air atmosphere, LRE242 forerunner's powder 810 ℃ of sintering 12 hours under nitrogen environment; This grinding, sintering process repeat 3 times altogether, to obtain the small scale LRE123 and the LRE242 powder of pure phase;

3) LRE123 powder after will sintering into mutually and LRE242 powder are even by the mixed of LRE123+ (10～30) mo1%LRE242, are pressed into the presoma sheet, and seed crystal control growing orientation is put at the top;

4) the presoma sheet is placed on the MgO single crystalline substrate, whole system is put into tightness system;

5) be warming up to the following 20-50 of peritectic melting temperature ℃ of LRE-BCO in 2 hours, be incubated 1 hour; Continue heating, be warming up to above 30 ± 5 ℃ of peritectic temperature, and be incubated 1.5 hours in 2 hours;

6) temperature is reduced to the Peritectic Reaction temperature in 15 minutes, with per hour 0.5 ℃ speed cooling 20-40 hour, quenching at last makes superconduction bulk material then;

Wherein, described LRE is Sm or Nd, and LRE242 is the LRE by the rich barium of agglomerating method synthetic under the nitrogen environment mutually ₂Ba ₄Cu ₂O ₉