JPH01108151A - Oxide superconducting materials - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is directed to M! It relates to oxide superconducting materials used in conductive magnets, Josephson junction devices, etc.

Conventional technology Superconducting materials have properties not found in other materials, such as 1) zero electrical resistance, 2) complete diamagnetism, and 3) Josephson effect, and are useful for power transportation and power generation. A wide range of applications are expected, including nuclear fusion plasma containment, magnetic floating trains, magnetic shielding, and high-speed computers. However, with conventional metallic superconductors, the highest superconducting transition temperature is around 23°C, and in actual use, it is necessary to cool them using expensive liquid helium and large-scale insulation equipment, which poses a major industrial problem. Ta. For this reason, searches have been made for materials that become superconductors at higher temperatures.

In February 1987, a new ceramic superconducting flj
M, YRa2c u307-X was found, and YRa2c
other rare earth elements (La, Nd, Sm, E
u.

Cds Dy, Ho, Er, Tm, Yb, Lu
) was also confirmed to become superconducting. These ceramics have a high superconducting transition temperature of about 95 K, can be cooled using inexpensive liquid nitrogen (boiling point 77 K), and have a smaller cooling device, so it is clear that the range of IN applications will be expanded. Waited. For this reason, many studies are currently being conducted on the production methods, physical properties, applications, etc. of these compounds.

Problems to be Solved by the Invention These ceramics are usually produced by mechanically mixing the oxides, carbonates, etc. of the respective metal components contained therein, and then calcining them.
) is produced by molding and firing the calcined powder.

In this method, in order to generate LnBa2CuxOy-x, which is a superconducting material and has a perovskite structure,
It is necessary to bake at a temperature of about 900°C or higher, and
When the temperature reaches 980℃ or higher, L n B 32C
Since the u30r-x phase decomposes, the firing temperature is limited to about 900°C to 980°C. However, due to the low sinterability of these ceramics, a sufficiently dense sintered body cannot be obtained within this temperature range, and when used in actual use, there are problems such as low mechanical strength and low critical current density. There was a drawback.

Means to solve the problem Chemical formula L n B B2 (CIJ +-zB iz)
30v-x (L rt is Y, La, Nd, Sm
, Ell, Cod, Dy, Ho, Er,
Tm, Yl), T, u), and Z is 0.02≦Z≦0.2
constitutes an oxide superconducting material within the range of

Action tree Sadaaki's L n B B2 (CIJ l-213i?
) In 107-X ceramics, B becomes a low melting point oxide.
By substituting and dissolving 1 into the B site of perovskite, it is possible to increase the density of the sintered body without deteriorating the properties at the same firing temperature. Furthermore, the temperature at which the sintered body density is the same decreases.

Example The present invention will be explained below with reference to Examples.

Example 1 Reagent grade Y2O3, BaCO3, Cll0. Bi? 0
1 powder, Y [3B2(CIJ +-?B i 2)
307-xJI composition, Bi substitution rate for Cu is 0%
, 1%, 2%.

5%, 10%, 20%, and 30%, each weighed to give a total weight of about 100 g, and these were wet-mixed in an agate ball mill with 50 tn I of ethanol at 6 p.m. After drying the mixture at 120°C, it was placed in an alumina crucible and calcined in air at 850°C for 5 hours. The calcined powder was pulverized and further calcined in air at 850°C for 5 hours. These twice-calcined powders were ground in an agate ball mill with 100 ynl of ethanol for 18 hours.
It was dried at 120°C. To the thus obtained powder, 5% of isopropanol solution in which polyvinyl butyral was dissolved at a concentration of 5% by weight was added and granulated. Granulated powder is 0.
Take 8g and mold it to 500kg/c with a diameter of 12mm.
, uniaxial pressure molding was carried out at a pressure of rrt2.

These molded bodies were heated at a heating rate of 300°C/hour in m-x,
Binder out 600℃-2 hours, baking 950℃-20
It was fired under conditions of a temperature decreasing rate of 100° C./hour.

The density of the obtained sintered body was measured based on the size of the sample, and the temperature change in electrical resistance was measured using the four-terminal method. Those ties! ■! are shown in Table 1. In the table, the temperature is divided into the temperature at which the resistance begins to decrease rapidly (Tco II) and the temperature at which the resistance becomes O (Tcn).

Table 1. As is clear from the various properties of the sintered body 7t, when CII is replaced with B1,
The density of the sintered body increased up to 20% substitution.

Moreover, there was almost no decrease in the superconducting transition temperature during this period.

Example 2 Reagent grade D y 20:l, B a CO3,C
u O, Bi;・03 powder, D 5/ B B2 (C
141-2B i , =)30v-x composition, the substitution ratio of Bi to Cu was 0% and 10%, and the total mold breakage was about 100 g, and the method was the same as in Example 1. A sintered body was created.

The density and superconducting transition temperature of these sintered bodies are 5.5%, respectively, with a Bi substitution rate of 0%. 72 g/crn3
, Tcon"96 and -Tcn=92, and with a Bl substitution rate of 10%, 5.98 g/c rn3, T
Con= 95 K-T ci! = 92 k″r:
It was f9.

Example 3 Reagent grade Ho2 (h, BaCO2, Cub, Bizo
3 powder, Ho Ba 2(Cu +-2B i z
)107-x- [with the substitution rate of pb for Cu being 0
% and 10%, and the total weight was about 100 g, and a sintered body was produced in the same manner as in Example 1.

The density and superconducting transition temperature of these sintered bodies are 5.70 g/cm3 and Tc at a B1 substitution rate of 0%, respectively.
On=96, Tel! = 93, and for Bi with a pJ rate of 10%, it is 5.93 g/cm3, Tco
n''94K-T CII=92K.

In addition to Y, T) y, tlo, [, a, N d , Srn
, Eu, Gd, Er, Tm, Yb, Lu
We conducted a similar experiment and found that although there are differences in the optimum firing temperature, no matter which i+ is formed, at a Bi substitution rate of 2 to 20%,
1 to 19! A denser sintered body was obtained than when the ratio was 0.

In the present invention, L nB a 2 (CII I -z Bi
The range of Z in zhOr-x is 0.02≦Z≦0.
The reason why Z is set at 2 is because when Z is less than 0.02, there is almost no effect of reducing the sintered density by 1 when added, and when it exceeds 0.2, the density decreases. .

Effects of the Invention According to the present invention, the chemical formula L n F3 a2 (Cu +
-zBiz)10v-x ([, n is Y, La,
Nd, Sm, Eu.

at least one metal selected from Gd, Dy, Ho, Er, Tm, Yb, Lu), and Z is 0.02≦
By using an oxide superconducting material within the range of Z≦0.2, it is possible to easily obtain a superconducting material with a high sintered density.

Claims (1)

[Claims] Chemical formula LnBa_2(Cu_1_-_ZBi_Z)_
3O_7_-_X (Ln is Y, La, Nd, Sm, Ee
, Gd, Dy, Ho, Er, Tm, Yb, Lu), and Z is 0.02
An oxide superconducting material characterized by Z being within the range of ≦Z≦0.2.