JPS63233070A - Preparation of superconductive ceramic - Google Patents

Abstract

PURPOSE:To prepare film of superconductive ceramic easily and inexpensively by coating a mixture of powder comprising a IIIa group element, IIa group element, and metal or compd. (such as oxide) of Cu with an org. solvent on a surface to be coated and calcining the coated product. CONSTITUTION:Powder of each at least one kind of IIIa group and IIa group element of the periodic table, and powder of metal or oxide of Cu are mixed with an org. solvent, and the mixture is coated or printed on a surface to be coated or printed. In this stage, frit may be added to the mixture for the purpose of increasing the adhesion to the surface. Then, the coated or printed powder is calcined to obtain film of superconductive ceramic. The above described ceramic has a constitution expressed by (A1-xBx)yCuOz [wherein (x) is 0.01-0.3; (y) is 1.0-2.2; (z) is 2.0-4.5]. In this constitution, it is preferred that A is at least one among Y, Gd, Yb, Eu, Tb, Dy, Ho, Er, Tm, Lu, Sc, and other lanthanoids; B is at least one among Ra, Ba, Sr, Ca, Mg, and Be.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for producing an oxide ceramic superconducting material.

The present invention relates to a method for producing a material exhibiting 2NiF-type superconductivity.

"Conventional technology" Conventionally, superconducting materials include elements such as mercury and lead, and NbN.

Alloys such as Nb3Ge and Nb3Ga or Nb* (A
A metal material made of a ternary element compound such as lo, aGeo, z) is used. However, the Tc (superconducting critical temperature) of these was up to 25K.

On the other hand, ceramic-based superconducting materials have attracted attention in recent years. This material was first obtained from IBM's Zurich laboratory.
It has been reported as an a-La-Cu-0 (baraquo)-based oxide high temperature superconductor, and has been further known as LSCO (cupric acid-lanthanum strontium). these are(
Attempts have only been made to mix the respective oxides in Al□Bx) ycuoz (oxidize and sinter only once) and make a table left.

``Conventional Problems'' However, the potential for superconductivity of these oxide tablet-shaped ceramics utilizes a single-layer vervskite structure, and if they are to be used in solid-state devices, a film or In particular a thickness of less than 50 μm, preferably 10 μm
There was a strong demand for a thin film with the following thickness. In addition, Tc.

There has been a strong desire to further increase the temperature at which the resistance becomes zero, preferably to operate at liquid nitrogen temperature (77K) or higher.

"Means to Solve the Problem" The present invention is a ceramic material that exhibits superconductivity at such high temperatures, and is intended to be used to form a membrane structure using K2NiF, the material for forming the mold.

The superconducting ceramic of the present invention is (Al□ax)ycu
Ozx=0.01-0.3. y = 1.0-2.2.
It can generally be expressed as z = 2.0 to 4.5. A uses one or more of elements selected from the intrum group and elements selected from other lanthanoids. According to the Physical and Chemistry Dictionary (Iwanami Shoten, published on April 1, 1963), the intrum group is Y.
(yttrium), Gd (gaddolium), Yb (interbium), Eu (europium), Tb (terbium), Dy (dysprosium), Ho (holmium), Er (erbium), Tm (thulium), Lu (lutetium) ).

Sc (scandium) and other lanthanides are used.

Also, B is Ra (radium), Ba (valium), S
r (strontium), Ca (calcium), Mg
One or more elements selected from (magnesium) and Be (beryllium) are used.

In the structure of the superconducting ceramic used in the present invention, six atoms of copper are formed into a layered structure, and carriers can easily move through this layer.
At-x Bx) A in ycuoz.

The element selected as B is important. In particular, the elements are elements of the isotoleum group or elements of the lanthanoids, generally the maO group of the periodic table of elements.

The present invention uses Ra, which is the na group in the periodic table of elements, as B.
Elements selected from (radium), Ba (valu-m), Sr (strontium), LCa (calcium), Mg (magnesium), and Be (beryllium) are used.

The present invention involves coating such ceramics on a substrate or a base body (a substrate on which ceramics have already been formed at least once is referred to as a base body) using a coating or printing method (coating it in a film form without using any film-forming means). Products that are formed into a film by printing (transferring a solution or paste mixed with raw materials to a film-forming means such as letterpress, intaglio, or lithographic printing, and then transferring the mixture) and firing this. It is. Therefore, for A, B, and copper in the above general formula, metals, metal oxides, or metal compounds can be used as starting materials. In addition, these are once baked into tablets, and the above-mentioned general formula (At-x
Bx) After forming the structure of ycuOz, it is once again pulverized, mixed with a solvent, and coated or printed on the surface to be coated to form a film. After drying it, it is then fired.

As a result, superconducting ceramics with a thin film structure can be obtained, and by processing this by photoetching and forming electrodes, insulating films, etc., it has become possible to fabricate superconducting elements, especially active elements.

"Operation" The KJiF4 type ceramic superconducting material of the present invention can be produced extremely easily. Particularly, for these, a metal, metal oxide or metal compound with a purity of 3N or 4N is used as the starting material, which is ground into a fine powder using a ball mill and mixed. Then, stoichiometrically (A, □Bx
) It is possible to arbitrarily change and control each value of Ly or X+LZ to be ycuoz.

Another feature of the present invention is that it does not require the use of particularly expensive equipment to produce such a superconducting material.

The present invention will be described below according to Examples.

"Example 1" As an example of the present invention, Y was used as A and Ba was used as B.

The starting material is yttrium oxide (Y2O) as a Y compound.
2) BaCO3 was used as the lBa compound and CuO was used as the copper compound. These were obtained from Kojundo Kagaku Kogyo Co., Ltd., using fine powders with a purity of 99.95χ or higher, and were selected so that x = 0.15 and y = 1.8.

The values of this X are 0.05, 0.1, 0.15, 0.2 and 0
．． It was varied in the range of 0.01 to 0.3.

Mix these thoroughly in a mortar and seal in capsules, weighing 3 kg.
/cm” load to make it into a tablet (size 10mm)
φX3mm)L, heated and fired.

The ceramic thus formed was once again pulverized. And the particle size is 5 μm or less, preferably 2 to 0.2
It was set as μm.

This was further mixed with a solvent. The solvents used were nitrocellulose, ethylcellulose, and acetobutylcellulose, and the diluents used were terpineol, pinene, turpentine, acetone, and ethyl alcohol. The viscosity and drying speed were adjusted by adjusting the type or amount of these.

For example, 60 to 70% by weight of the above mixture, flint 3
~10% by weight, 5~20% by weight of cellulose resin, etc., and 15~20% by weight of acetate were used.

These mixed solvents were filled into recesses in offset printing or intaglio printing, and printing was performed on the printing surface. By doing so, it is possible to reduce the thickness of the printed ceramic to 5 μm or less.

Further, it was dried at 200 to 400°C. Next, in an oxidizing atmosphere, e.g. air, at a temperature of 500 to 1200°C, e.g. 70°C.
It was heated and oxidized at 0°C for 8 hours and then fired.

By this baking, the surface to be coated is coated with a thickness of 0.2 to 15 μm, for example, 5 μm.
It was possible to form the film to a thickness of μm.

Next, this sample was heated in 0□-Ar with a reduced amount of oxygen (600-1200°C, 3-30 hours, e.g. 800°C).
, 20 hours) for reduction. Then, a KgNiFi type structure became more prominently observed.

Furthermore, by using such a printing method, superconducting ceramics can be selectively formed only at predetermined positions on a substrate or base body.

Using this sample, the relationship between resistivity and temperature was investigated. As a result, it was possible to observe a Tc onset of 53K and a Tco of 41K as the maximum temperature obtained.

“Example 2” In this example, Y and Yb are x:x”=
The metals were mixed 1:1. As B, Ba was used as a metal. The rest is the same as in Example 1.

38K as Tc onset 27K as Tco
was able to obtain.

In the present invention, this once-printed surface is used as a substrate, and the same component or different X+V+Z is further applied to the upper surface.
Or they were formed by layering ceramics of different elements. Then, the thickness further increased by 2 to 10 μm each time, but Tc and Tco could also be increased to 5 to 20 each time.

"Example 3" In Example 1, Y was used as A as a metal complex salt. Furthermore, copper sulfate was used as the copper. Further, barium carbonate was used as Ba, and A, B, and Cu were all used as solutions. This mixed solution was diluted with the diluent shown in Example 1. Further, this was applied by rotation using a spinner. Then 0.
A thin film of 3-5 μm, for example 1 μm, could be made after firing, giving a Tc of 45K and a Tco of 38K.

In the present invention, a screen printing method can be applied to Example 1. However, in this method, the printed surface must be made as thick as 20 to 50 μm in one printing;
This is insufficient for forming a thin film of 10 μm or less. However, it has other characteristics such as excellent mass production and ease of use.

"Effects" The present invention has made it possible to create a superconducting ceramic film, which was previously considered impossible.

In the present invention, by coating or printing, a compound containing a target material, that is, a material represented by (A+-x Bx)ycuoz, is obtained.

Furthermore, in order to make it easier to form a copper layer structure within the molecular structure of the compound of this target material, a plurality of elements Ila and II[a in the atomic periodic table may be mixed. In this way, the presence of vacancies such as voids can be further removed in the final completed compound, and as a result, Tc onset and Tco
It is estimated that the temperature can be increased even further.

In addition, the superconducting ceramic represented by the molecular formula of the present invention has a layered structure of copper oxide as the presumed superconducting mechanism, and the layered structure also has one or two layers within one molecule. It is assumed that the carrier is superconducting.

The present invention relates to other molecular formulas (A+-x Bx)y'
cuzOz'J'-2,6~4.4+z' =4.0
~8.0 For example y+=3. Z+=7 or y' -2+
z' =6+ (8I-X Bx)y'cu60z'
It goes without saying that this is equivalent to y''-5,z'=14 in .

Claims (1)

[Claims] 1. When producing a material having superconducting properties of a compound of copper and one or more elements selected from groups IIIa and IIa of the periodic table of elements, these metals or metals Production of superconducting ceramics characterized by comprising a step of mixing a powder of a compound such as an oxide with an organic solvent and applying or printing it on a surface to be coated, and a step of firing the powder applied or printed by the step. Method. 2. In claim 1, the Periodic Table of Elements III
The compound of copper and an element selected from group a and group IIa is (A_1_-_xB_x)_yCuO_zx
=0.01~0.3, y=1.0~2.2, z=2.0
~4.5 composition, A is Y (yttrium), G
d (gadolinium), Yb (ytterbium), E
One type selected from u (europium), Tb (terbium), Dy (dysprosium), Ho (holmium), Er (erbium), Tm (thulium), Lu (lutetium), Sc (scandium) and other lanthanoids, or Consisting of multiple types of elements, B is Ra (radium), Ba (valume), Sr (strontium), Ca (calcium), and Mg (magnesium).
A method for producing superconducting ceramics, characterized in that a superconducting material made of one or more elements selected from , Be (beryllium), and Be (beryllium) is used. 3. A method for producing superconducting ceramics according to claim 1, characterized in that a frit is added to the solvent to improve adhesion to the surface to be coated.