JPH04114917A - Superconductor - Google Patents

Abstract

PURPOSE:To obtain a superconductor having improve coordination superconductor with the same kind of superconductor and to use the superconductor and the same kind of superconductor having a superconducting transition temperature different from that of the superconductor by forming crystal containing a blocking layer of BaO/CuO/CuO/BaO 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 Pb; p is 0-0.2; q is 0.3-0.5; s is 5-5.8). The superconductor has a blocking layer of BaO/CuO/CuO/BaO type comprising a layer made of Ba, Sr, alpha and oxygen and a layer made of Cu and oxygen. The superconductor is produced by powder blending method, deposition method, sputtering method, etc., made into a tape state, linear 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, Suitable for applications where power loss is a problem, such as transformers and rectifiers, and also for Josephson elements, SQUID
Element, superconducting transistor5. The present invention relates to superconductors suitable as various elements such as superconducting microwave three-dimensional circuits, and furthermore suitable as various functional materials such as infrared detection materials and 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 CuO2 layers and other layers. moreover,
Anything other than the CuO2 layer is “Physica C” 1
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/Bi2
O2/SrO type, B a O/ T I 202 /
B a O or BaO/TIO/BaO type, SrO
/PbO-Cu-PbO/SrO type, S ro/ (P
b, Cu)O/SrO or S r O/ (P b
, S r) 0/S rO type, Ln2O3 type (Ln
is an element selected from NdXSm, Eu and Gd)
There are different types.

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 Cub2 plane and the closest O 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
,uO,.

This is difficult due to inconsistencies in crystal size in the direction parallel to the plane and diffusion of constituent elements from one superconductor to another 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, Y1Ba2Cu3O7-y superconductor is B
It has a blocking layer of aO/CuO/CuO/BaO type, and has a superconducting transition temperature of 90°C, but it has a blocking layer of the lever type of copper composite oxide superconductor that has been found so far. This is the only one that has .

<Problems to be Solved by the Invention> The purpose of the invention is to solve the problem of Y, Ba2Cu, o8. The same type of superconductor (BaO/CuO/CuO
An object of the present invention is to provide a copper composite oxide superconductor that not only has a blocking layer of the type B a O type) and has good compatibility with the blocking layer, but also has a different superconducting transition temperature from the blocking layer and can be easily used in common.

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

{(Ba1-p S r, ) l-a α. ) 2C
u30゜However, α: Element selected from La and pb 0≦p≦0.2 0.3≦q≦0.5 5, Q<s≦5.8 In the following, this will be referred to as the first invention. Make it.

Further, the present invention provides a superconductor represented by the following general formula.

((B al-t S r t ) i-u C1u
) 2-V(βi-w (Ca 1-X S r
x ) w ) 21) VCu,,o.

however, α: Element selected from La and Pb β: Y, Nd, Sm, Eu, Gd, Dy.

Element selected from I-Io, Er, Tm, Yb and Lu 0≦t≦0.2 Q<u≦0.5 0≦v<0. 2 0≦W≦0.5 0≦x<0. 2 9, 5<y≦10.1 Hereinafter, this will be referred to as the second invention.

In the first and second inventions, only one type of each of the elements α and β may be selected, or two or more types may be selected.

The superconductors of the first and second inventions have crystal structures as shown in FIGS. 1 and 2, respectively, and include a layer of (Ba, Sr1α) and oxygen, a layer of Cu and oxygen, and a layer of Cu and oxygen. and another layer by (B a.

BaO/ formed from Sr, α) and oxygen debris
It has a CuO/CuO/BaO type blocking layer.

Now, in the superconductor of the first invention, when the structure is ideally realized, S in the general formula is 6.0, but since the structure is likely to cause oxygen vacancies, it is usually 5.0. Q<s≦5
．． A composition range of 8 is allowed. Also, regarding p,
Due to the solid solubility limit of Ba and Sr, a restriction of Q<p≦0.2 is added.

In the superconductor of the first invention, charge is provided by holes. As described above, when charge is provided by holes, the superconductor becomes a superconductor when the hole concentration is 0.01 or more and 0.5 or less per Cu, as in the conventional copper composite oxide superconductor. Then, the hole concentration per Cu is 2 x s
/ 3-2 X Q / 310/3, so 2.01<2xs/3-2xq/3-4/3<2.
Must be 50. Preferably 2.10<2x
s/3-2Xq/3-4/3<2.30. However, the valence of each element was set to be +3 valence for La, +2 valence for Ba and Sr, and 12 valence for O. Also, the valence of Pb is +2 and +4.
Since it can have a valence, it can be considered a mixed valence of +2 and +4,
The average value was +3.

2.01<2xs/3-2xq/3-4/3<2.50
In order to easily satisfy this restriction, S should be smaller than the value when the structure is ideally realized.

Furthermore, q is set to 0.000 to stabilize the structure shown in FIG. 1 and to reduce excess holes. A restriction of 3≦q≦0.5 is added.

The lattice constant in the a-b plane direction of the crystal structure of the superconductor of the first invention depends on the type of element α, the composition ratio of each element, and the oxygen content (S
), and since the crystal is orthorhombic, there is a slight deviation in the a-axis and b-axis directions, but it is approximately 3.88, which can be compared to Cu in the CuO2 plane and the O closest to it. If expressed as the distance, it becomes 1.9 people, and Y, Ba2Cu,,o
8-, and has good consistency with this case. In addition, the C-axis length of the lattice constant is about 20.6, and the C-axis length of the repeating unit is 1/2 of the C-axis length of the lattice constant, which is about 1
0° There are 3 people.

Next, in the superconductor of the second invention, when the structure is ideally realized, y in the general formula is 10.0, but like the first invention, the structure is likely to cause oxygen vacancies, so it is usually A composition range of 9.5<4≦10.1 is allowed.

In addition, the solid solubility limit of Ba and Sr is the same as in the first invention, O≦
A restriction of t≦0.2 is added.

In the superconductor of the second invention, charge is also given by holes, and like the conventional copper composite oxide superconductor, it becomes a superconductor when the hole concentration is 0.01 or more and 0.5 or less per Cu. . Then, the hole concentration per Cu is 2X'Y
/ 5- (2+u) X (2-v)/5-
(3-w) X (2+v) Since it is given by 15-2, 2.01<2Xy15-(2+u)x(2-v)1
5-(3-w)X(2+v)15<2.50. Preferably, 2°10<2Xy15-
(2+u)X (2-v)15- (3-w)X (2
+v)15<2.30.

However, the valence of each element is +3 for La and Ba.

5rXCa is +2 valent, Y, Nd, Sm, EuXGd, D
y, Ho, Er, Tm, Tb, and Lu were set to +3 valence, and O was set to 12 valence. Further, since the valence of Pb can be +2 and +4, it is considered to be a mixed valence of +2 and +4, and the average valence is +3.

2.01<2Xy15-(2+u)X (2-v)15
In order to easily satisfy the restriction -(3-w)X (2+v)15<2.50, y should be close to the value when the structure is ideally realized.

As shown in Figure 2, the element β is located on the plane where it exists (a
In order to prevent oxygen from existing in the b-plane), the ionic radius must be small, about 1100p. From this condition, the elements β are Y and Nd.

It must be selected from Sm, Eu, Gd, Dy, Ho, Er, Tm, Yb and Lu, and in order to stabilize the structure, Y, Dy, Ho, Er.

Yb is preferred. Further, due to the solid solubility limit between element β and Ca and Sr, a restriction of 0≦W≦0,5 is added.

Furthermore, for uXv and x, respectively, O<u≦0.5.0≦V<0.2.0≦
A restriction is added that x<0.2.

The lattice constant in the a-b plane direction of the crystal structure of the superconductor of the second invention also varies depending on the types of elements α and β, the composition ratio of each element, and the oxygen content (y), and the crystal is slightly deviated from tetragonal. In some cases, it becomes an orthorhombic crystal and has a slight shape in the a-axis direction and the b-axis direction, but in about 3.8 people, this is called Cub, Cc+ in the plane, u, and the nearest 0. Expressed in terms of the distance, the number is 1.9, which is almost the same as in the case of the Y1Ba2Cu3O7-2 superconductor and the superconductor of the first invention, and has good consistency with these superconductors. Further, the C-axis length of the lattice constant is about 34 people, and the C-axis length of the repeating unit is 1/2 of the C-axis length of the lattice constant, which is about 17 people.

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, Si
, MgO, LaGaO3, LaAlO3, SrTiO3
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 when 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 vapor deposition methods such as electron beam evaporation and laser evaporation, which can preferably control lamination on the atomic order, or various sputtering methods such as magnetron sputtering can be used.

It is also possible to use a chemical vapor deposition method using a halide or an organic metal, an atomization method using a nitrate or an organic acid, or a coating method using an alkoxide or the like.

<Example> Example 1 BaCO3, SrCO3, T, a2 (CO3)3・X
Each powder of H2OXPbO1CuO was converted into Ba:Sr:La:
Pb:Cu:1. ．． 26: 0.14: 0゜0
The mixture was weighed so as to have a ratio of 3:0.57:3.0, crushed and mixed in an agate mortar, placed in an A1□03 container, and calcined in air at 900°C for 12 hours.

Thereafter, it was ground again in an agate mortar, fired at 900° C. for 1 day in an oxygen atmosphere of 100 atm, and then slowly cooled. The pellets thus obtained were further heated to an oxygen partial pressure of 0.
After heat treatment at 750° C. for 4 hours in an oxygen atmosphere of 1 atm or less, it was rapidly cooled.

A part of the obtained pellets was crushed and the crystal structure was analyzed by powder X-ray diffraction, and the crystal structure was as shown in FIG. 1. Also, at this time, when the lattice constant was determined, a
= 3.86A, c = 20° 5 people. If this a-axis length is expressed as the distance between CU in the CuO2 plane and the O closest to it, it is 1.93A, and Y, Ba2Cu408
-, which is almost the same as that of superconductors and has excellent consistency with it.

Also, the composition is ((Bao9S ro', I) 0.7
(La0.05P 1)0.9. ) 0.3 )
2Cu3o,7, the superconducting transition temperature was 20.

Example 2 BaCO3, SrCO3, La2 (CO3)3 x
The raw material powders of H20, PbO, Er, C3, CaCO3, and CuO are converted into Ba:Sr:La:Pb:Er:Ca:C
u is 1.62:0.22:0.02:0.18:1.3
:0.67・5. The mixture was weighed so as to have a weight of 0.0, pulverized and mixed in an agate mortar, placed in an Al2O3 container, and calcined in air at 900°C for 12 hours. After that, it was crushed again in an agate mortar, PbO raw material powder was added, mixed, formed into pellets, and heated to 900°C in an oxygen atmosphere of 800 atm.
After firing for 1 day, it was rapidly cooled. The pellets thus obtained were further heat-treated at 400° C. for 40 minutes in an oxygen-argon mixed gas atmosphere with an oxygen partial pressure of 1 atm, and then slowly cooled.

A part of the obtained pellets was crushed and the crystal structure was analyzed by powder X-ray diffraction, and the crystal structure was as shown in FIG. 2. Also, at this time, when the lattice constant was determined, a
= 3.86 people, c = 34°0 people. If this a-axis length is expressed as the distance between CU in the CuO2 plane and the O closest to it, it is 1.93 people, and Y, Ba2Cu, ,C
8-, it is almost the same as the case of superconductors and has excellent consistency with it.

Also, the composition is ((Ba0.9 S rol) 0.9
(LaO, I P 1) 0.9 ) 0.1 ) 2
(Er0.65 (CaO,'15Sroo5).

35) 2Cu50□. . and the superconducting transition temperature is 60
It was.

Example 3 CuO powder was formed into a pellet shape and fired at 900° C. for 5 hours to obtain a sintered body. Also, SrCO3, BaCO3,
Each powder of La(C03)3 ・XH2O1PbO1CuO is 0.81 Sr:Ba:La:Pb:Cu
:0.04:0.1.3:0.02:1.0, mixed, formed into pellets, and heated to 900℃ for 5 minutes.
The composition is SrO, 81Ba0.04L ao
, 13P bo, 02CLl 10X sintered bodies were obtained. Similarly, Y2O3, CaCo3, SrCO3, C
Each powder of uO was mixed with Y:Ca:Sr:CU at 0.7:0.2.
They were weighed and mixed so that the ratio was 7:0.03:1.0, formed into pellets, and baked at 800°C for 5 hours, so that the composition was Y. A sintered body named 7Cao27Sroo3Cu, OX was obtained.

Next, the three types of sintered bodies mentioned above were applied to Targera I, ■,
(2), (2), and vapor deposition was performed using an ArF excimer laser. That is, the target and the 5rTi03 substrate were placed in a vacuum chamber, the substrate was heated, and while a small amount of 02 gas and N20 gas was flowing, the excimer laser was applied to the targets ■, ■, ■, ■, ■, ■. , ■,...
... was repeatedly irradiated to cause ablation to form a layer of each composition on the substrate, thereby forming a thin film.

When the crystal structure of the obtained thin film was analyzed, it was found to have the structure shown in FIG. Further, when the lattice constants were determined, a=3.86 and c=34°0. This a
If the axial length is expressed as the distance between CU in the CuO2 plane and the O closest to it, it will be 1.93 people, and Y, Ba2Cu
, 08-, is almost the same as that of superconductors and has excellent consistency therewith.

In addition, the total composition of the thin film is ((B a O, 95S
ro, C5) 0.85 (Lao, P bo, +)
o, +s) 2 (Y.7 (Cao, Sro,)
. 3) 2Cu, 099°, and the superconducting transition temperature was 55K.

<Effects of the Invention> As shown in the examples, the superconductor of this invention is of the same type as the conventional Y, Ba2Cu, C8, superconductor (
It has a crystal structure that includes a blocking layer (BaO/CuO/CuO/BaO type), and is not only compatible with this, but also has a different superconducting transition temperature, making it easy to use in common. be.

[Brief explanation of the drawing]

FIGS. 1 and 2 are model diagrams of the crystal structure of the superconductor of the present invention.

Claims (1)

[Claims] (1) A superconductor whose main component is a copper composite oxide represented by the following general formula. {(Ba_1_-_pSr_p)_1_-_qα_q}
_2Cu_3O_s However, α: Element selected from La and Pb 0≦p≦0.2 0.3≦q≦0.5 5.0<s≦5.8 (2) Copper composite represented by the following general formula A superconductor whose main component is oxide. {(Ba_1_-_tSr_t)_1_-_uα_u}
_2_-_v{β_1_-_w(Ca_1_-_xSr
_x)_w}_2_+_vCu_5O_y However, α: Element selected from La and Pb β: Element selected from Y, Nd, Sm, Eu, Gd, Dy, Ho, Er, Tm, Yb and Lu 0≦t≦0 .2 0<u≦0.5 0≦v<0.2 0≦w≦0.5 0≦x<0.2 9.5<y≦10.1