JPH04114915A - Superconductor - Google Patents

Abstract

PURPOSE:To improve coordination of superconductor with the same kind of superconductor and to attain a high superconducting transition temperature different from that of the same kind of superconductor by forming crystal structure containing a blocking layer of La2O2 type shown by the formula. CONSTITUTION:This superconductor consists essentially of a copper compound oxide shown by the formula (with the proviso that alpha is element selected from La and P1; beta is element selected from Ba and Sr; gamma is element selected from Ca and Sr; delta is element selected from Y, Nd, Sm, Eu, Gd, etc.; p is 0-0.75; q is 0-0.2; gamma is 0-0.5; s is 7.9-8.5). The superconductor has a blocking layer of La2O2 type made of elements alpha and beta and oxygen. The superconductor is produced by powder blending method, deposition method, sputtering method, etc., made into a tape state, filamentous state and sheetlike state, etc., and used.

Description

[Detailed Description of the Invention] <Industrial Application Field> This invention is applicable to nuclear fusion reactors, magnetohydrodynamic generators, accelerators, rotating electrical equipment (such as electric motors and generators), magnetic separators, magnetic levitation trains, and magnetic levitation. Suitable as a material for magnet coils in automobiles, magnetic levitation elevators, nuclear magnetic resonance tomography diagnostic equipment, magnetic propulsion ships, electron beam exposure equipment, single crystal manufacturing equipment, various experimental equipment, etc. Also suitable for power transmission lines, electrical energy storage devices, It is suitable for applications where power loss is a problem, such as transformers and rectifiers, and is also suitable for various devices such as Josephson devices, 5QUTD devices, superconducting transistors, and superconducting microwave three-dimensional circuits.It is also suitable for infrared detection materials,
This invention relates to superconductors suitable as various functional materials such as magnetic shielding materials.

<Prior Art> Twenty types of copper composite oxide superconductors having different crystal structures have been discovered so far. When the crystal structures of these superconductors are further subdivided, the repeating units of the crystal structure can be classified into CuO□ layers and other layers. moreover,
Other than the CuO2 layer, “Physica XC1
67, p. 515 (1990), the layer can be classified into a blocking layer and a meso-eating layer depending on the thickness of the layer in the direction perpendicular to the CuO2 layer (C-axis direction). In this way, the blocking layer has La2o2 type, B a
O/ Cu O/ B a O type, B a O/ C
u O/ Cu O/ B a O type, SrO/B 1
202/S ro type, B a O/T 1202/
B a O or BaO/T] O/B a
O type, SrO/PbO-CuPbO/SrO type, S
ro/ (Pb, Cu)O/SrO or S rO/
(Pb, S r) 0/S ro type, Ln2O3
There are eight types (Ln is an element selected from Nd, Sm, Eu, and Gd).

Now, when examining the lattice constant (a-axis length or b-axis length) of a conventional copper composite oxide superconductor in a direction parallel to the CuO2 plane, it differs depending on the type of blocking layer. C
When the crystal size in the direction parallel to the uO2 plane is expressed as the distance between Cu in the CuO2 plane and the O closest to it, it is distributed in the range of 1.89 to 1.97.

By the way, when using copper composite oxide superconductors, it would be convenient if superconductors having different superconducting transition temperatures could be used together. For example, when constructing various elements and sensors, new effects can be expected if materials with different superconducting transition temperatures can be integrated and arranged in layers. however,
The common use of superconductors with different types of blocking layers is C
Inconsistency in the crystal size in the direction parallel to the uO2 plane,
This is quite difficult due to the diffusion of constituent elements from one superconductor to the other during fabrication. Therefore, it is desired to obtain multiple types of superconductors that contain the same type of blocking layer but have different superconducting transition temperatures.

For example, the La185Sro, 15Cu104 superconductor and the La16S ro, 4Ca1Cu, 06 superconductor have the same type of blocking layer (La202 type), so they can be easily used in common. The superconducting transition temperatures are then 35 and 60, respectively, well meeting the above-mentioned wishes. However, the scope of use is limited with only two types.

<Problem to be solved by the invention> The purpose of this invention is to solve the problems that Lal, B5S ro, l5cul
O4 superconductor and La1,6 S ro4Cal C1
The object of the present invention is to provide a copper composite oxide superconductor that not only includes a blocking layer of the same type (La20□ type) as the 1206 superconductor and has good compatibility with them, but also has a different superconducting transition temperature from them.

<Means for Solving the Problems> In order to achieve the above object, the present invention provides a superconductor represented by the following general formula.

(α+-pβ11)2-0 (71-rδ,) 2+Q C1130s However, α: Element selected from La and Pb β: Element selected from Ba and Sr γ: Element selected from Ca and Sr δ: YXNd, Sm, Eu, Gd, Dy.

Element selected from Ho, Er, Tm, Yb and Lu 0<p≦0.75 0≦q<Q, 2 0≦r<0. 5 7, 9<s<8. 5 In this invention, α, β, γ, and δ are each only 1
You may select one species or two or more species.

The superconductor of the present invention has a crystal structure as shown in the drawings, and has an a202 type blocking layer formed of elements α, β and oxygen.

Now, in the superconductor of the present invention, when the structure is ideally realized, S in the general formula is 8.0, but since there is usually an excess or deficiency in the amount of oxygen, 7.9<s<8. A composition range of 5 is allowed. As for p, a limit of 0<p≦0.75 is added due to the solid solubility limit of Ba and Sr.

In the superconductor of this invention, charge is given by holes. When charge is provided by holes in this way, the hole concentration is 0.01 or more per Cu, as in conventional copper composite oxide superconductors. When it is 5 or less, it becomes a superconductor. Then, the hole concentration per Cu is -(3X
(], -1)) +2Xp) X (2-q) /3
-(2x (1-r) +3Xr) X (2+q)/
Since it is given by 3+2Xs/3-2, 2. OL<-
(3x (1-p)+2Xp) X (2-q) /3
-(2X (:I--r) +3Xr) X (2+q
)/3+2Xs/3<2.50. Preferably, 2.10<(3x (1-p) +2xp)
X (2-q)/3(2X (1-r) +3xr)
X(2+q)/3+2xs/3<2.30.

However, the valence of each element is: La is +3 valence, Ba, S
r, Ca is +2 valent, YXNd, Sm, Eu, Gd, Dy
, Ho.

Er, Tm, Tb, and Lu were set to +3 valence. Further, since Pb can have a valence of +2 and +4, it is considered to be a mixed valence of +2 and -4, and the average valence is +3.

In addition, 2.01. <~(3×(:1.p)+2X1
))X (2Q) /3 (2X (1-r) +3
In order to easily satisfy the restriction Xr)X (2+q)/3+2Xs/3<2.50, S should be larger than the value when the structure is ideally realized.

The element δ is present in the plane (ab
The ionic radius must be small, about 1100p, to prevent oxygen from existing within the plane. From this condition, the elements δ are Y and Nd.

Sm, EuXGd, Dy, Ho, %E r, TmXYb
and Lu, but to make the structure more stable, Y , , D y XHO%Er,
Preferably it is Yb. Further, due to the solid solubility limit of the element δ, the following restrictions are added: 0≦r<Q, 5.

Furthermore, in q, in order to stabilize the structure shown in the drawing,
A restriction of 0≦q<Q, 2, is added.

The lattice constants of the crystal structure of the superconductor of this invention are elements α,
Although it depends on the types of β, γ, and δ and the oxygen content (S), it takes about 3.8 people (a-axis length and b-axis length) to convert CuO2
The number of people is 1.9 when expressed as the distance between Cu in a plane and O which is closest to it.

This is La 1. B5S r o, 15Cu
104 and La 16Sro4Ca1Cu206, and has good compatibility with these superconductors. In addition, the C-axis length of the lattice constant is about 23A, and the C-axis length of the repeating unit is 1/2 of the C-axis length of the lattice constant, which is about 11~
It is 12A.

The superconductor of the present invention can be used in various forms such as a tape, a line, a fiber, and a sheet.

It can also be formed on a reinforcing wire made of carbon fiber, ceramics, or metal such as gold or silver. It can also be used by filling it into a reinforcing hollow material such as a silver sheath. Furthermore, a superconducting wire with a multifilamentary wire structure can be made using a matrix of copper or the like. Also, 51
1Mg0. LaGaO3, LaAlO3, 5rTi03
It can be formed as a thin film on a substrate such as the like, and used as various elements or as LSI wiring.

The superconductor of this invention can be easily handled if used in conjunction with a refrigerator that utilizes the Peltier effect or the like.

The superconductor of this invention can be manufactured by various methods.

For example, well-known powder mixing methods can be used. In addition, various evaporation methods such as electron beam evaporation and laser evaporation, various sputtering methods such as magnetron sputtering, chemical vapor deposition using halides and organic metals, and nitrate It can be carried out by an atomization method using an organic acid or the like, or by a coating method using an alkoxide or the like.

In addition, the superconductor of this invention is prone to oxygen vacancies,
Since the number of charge carriers, ie, holes, in the crystal decreases, it is preferable to perform heat treatment under an oxygen partial pressure of 1 to 400 atmospheres after firing.

<Example> Example 1 L, a2 (CO3)3・xH2O, PbO, BaCO
3. Each powder of CaCO3, Y2O3, and cuo was added to La:
Pb:Ba:Ca:Y:Cu is 0. Yes, 6:1
．． Weigh it so that the ratio is 3 + 1.2: 0.8: 3.0, and P
After crushing and mixing the powder except bO in an agate mortar, AI
. 03 container and calcined in air at 900°C for 12 hours. After that, it is crushed again in an agate mortar, PbO powder is added, mixed, and formed into pellets until the oxygen partial pressure is 0.
．． After firing at 900° C. for 3 days in an atmosphere of 1 atm or less, it was rapidly cooled. The pellets thus obtained were further heat-treated at 750° C. for 4 hours in an oxygen-argon mixed gas atmosphere with an oxygen partial pressure of 200 atm, and then slowly cooled.

A part of the obtained pellet was crushed and analyzed using powder X-ray diffraction, and it was confirmed that the pellet had the crystal structure shown in the drawing. Also, when the lattice constant was determined at this time,
a=3.82A, c=22°78. This a-axis length is defined as Cu in the CuO2 plane and O closest to it.
If expressed in terms of distance from
．． 85s r 0.15cu104, La, 6Sro,
, , Ca, and Cu206, and has excellent compatibility with these.

Also, the composition is (Lao, o, P I) o3Ba0.65
) 2]-1°o (Ca0.6 Yo, 4) 2. OC1130
g, 2, the superconducting transition temperature was 65.

Example 2 La2 (CO3)3.xH2O,, PbO,, Ba
CO3, SrCO3, CaCO3, Er2O3, CuO
Each powder of La:Pb:Ba:Sr:Ca:
Er:Cu is 0.195:0.683:0.975:0
．． 20:1. The powder was weighed so that the ratio was oa:o, 923:3.0, and the powder excluding PbO was ground and mixed in an agate mortar, placed in an A1□03 container, and heated at 900℃ in air for 1 hour.
It was calcined for 2 hours. After that, crush it again in an agate mortar and P
bO powder was added, mixed, formed into pellets, fired at 920° C. for 3 days in an atmosphere with an oxygen partial pressure of 0.1 atm or less, and then rapidly cooled. The pellets thus obtained were further heat-treated at 800° C. for 4 hours in an oxygen-argon mixed gas atmosphere with an oxygen partial pressure of 10 atm, and then slowly cooled.

When the obtained pellet was analyzed in the same manner as in Example 1, it was confirmed that it had the crystal structure shown in the drawing.

Moreover, the lattice constant is a=3. 84 people, c=23. OA
Met. If this a-axis length is expressed as the distance between Cu in the CuO□ plane and the O closest to it, it is 1.92A, which is also La.

,,S r o, ,,Cu, 04, La, 6Sr
o, 4 Ca.

Excellent consistency with Cu206.

In addition, the composition is (La., Pbo35Bao, S rO
, 05) 1.95 (Cao, 5 S ro, 05E
ro, 45) 2.05Cu3081, the superconducting transition temperature was 62.

<Effects of the Invention> As shown in the examples, the superconductor of the present invention is a superconductor of the conventional La18,5ro15Cu204 and La.

The same type of mold as 6Sro4Ca1Cu206 (La2o
It has a crystal structure including a type 2) blocking layer, and not only has good compatibility with these, but also has a high superconducting transition temperature different from those of these copper composite oxide superconductors.

[Brief explanation of drawings]

The drawing is a model diagram of the crystal structure of the superconductor of the present invention.

Claims (1)

[Claims] A superconductor whose main component is a copper complex oxide represented by the following general formula. (α_1_-_pβ_p)_2_-_q (γ_1_-_rδ_r)_2_+_qCu_3O_s
However, α: an element selected from La and Pb β: an element selected from Ba and Sr γ: an element selected from Ca and Sr δ: Y, Nd, Sm, Eu, Gd, Dy, Ho, Er, Element selected from Tm, Yb and Lu 0<p≦0.75 0≦q<0.2 0≦r<0.5 7.9<s<8.5