JPH01115886A - Superconducting material - Google Patents

Abstract

PURPOSE:To obtain the titled material, useful as Josephson elements, superconducting magnets, magnetic shields, etc., and having excellent stability (environmental resistance), by forming a fluorine-containing layer on the surface of an oxide ceramic based superconductor. CONSTITUTION:The surface of an oxide ceramic based superconductor, such as R-M-Cu-O based superconductor (R is rare earth element including Sc and Y; M is Ca, Ba or Sr), is subjected to fluorine plasma treatment by exposure to fluorine converted into a plasma using a plasma reactor, etc., for a given time to form a fluorine-containing layer.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a superconducting material used for a mechanical device, a superconducting magnet, a magnetic shield, etc.

[Conventional technology]

The main oxide ceramic superconducting materials include Dupo
Discovered by Sleight et al. of nt 1. riHa-Pb-Di
-0 series (perovskite structure), ll3M Bedno
There is a Ba-La-Cu-0 system (arcuate perovskite structure) discovered by RZ et al., and a Ba-Y-Cu-0 system (oxygen-deficient layered perovskite structure) discovered by Chu et al. of the University of Houston.

[Problem that the invention seeks to solve]

However, the conventional type 1! Conductive materials tend to react with moisture, leading to deterioration of critical temperature.

For example, Bas, which has the highest critical temperature and is currently attracting attention.
According to a report from the Bell Institute, Y'+ Cus Ot -a reacts as follows.

Bat YCus Ot ↓ H, O Ym B aCu O, + B a (O old 1 + Cu
O+Q The present invention is intended to solve such problems, and its purpose is to provide a super-fr1 product with excellent stability (environmental resistance)! ! The purpose is to obtain three materials.

[Means for solving problems]

In order to solve the above problems, the superconducting material of the present invention has the following features: 1)
A layer containing fluorine is formed on the surface of the oxide ceramic superconducting material.2) The oxide ceramic superconductor is a R-M-Cu-0 thread W1s body (where R is SC%).
1@l or a combination of multiple elements selected from the group consisting of rare earth elements including Y, M is CFLs B ELs
3) A fluorine plasma treatment is used to form a layer containing fluorine.

〔Example〕

The present invention will be described in detail below with reference to Examples.

Example 1 First, NH with a thickness of 6 μm is formed on an butolium-based stabilized zirconia (YS2) substrate by triple photoelectron beam evaporation. Table 1 shows the composition of the thin film, and the target used at this time is an R-Cu alloy (here R is a rare earth element shown in Table 1) prepared in a predetermined element ratio for compositions A to E. ), 5r-Cu alloy, and Ba-Cu alloy, and E has two targets, Ba-Pb alloy and Pb-13i alloy. (R-I3 for A-E target
A was also prepared, but no good alloy could be obtained. )
The vapor deposition atmosphere was 7 oxygen pressures, 10-' TOrrq substrates, and 830'C. Since the formed thin film lacks oxygen, it is then annealed at 550 to 870° C. in an oxygen atmosphere for 15 hours to obtain a superconducting thin film. Cooling after annealing is gradual cooling at about 50° C./H.

Next, a plasma reactor (Yamato Scientific Co., Ltd. PR
-501A) for 1 hour (
Fluorine plasma treatment is performed twice for 30 minutes to form a fluorine-containing layer on the surface of the superconducting thin film.

While etching a sample that had been subjected to fluorine plasma treatment, the depth to which fluorine had penetrated was analyzed using X-ray electron spectroscopy (XPS). Since XPS has a wide detection range and etching is not uniform, the depth accuracy is not accurate, but it is thought to be around 0.08μ. Also, since a chemical shift was observed in the photoelectrons of fluorine, it seems that some of the fluorine is bonded to other elements.

Table 1 Next, the stability (environmental resistance) of the obtained sample was investigated. For evaluation, a durability test was conducted in which the sample was exposed to an atmosphere at a temperature of 45° C. and humidity of 85%, and the amount of change in inductance of the sample before and after the test was measured. The measurement temperature was 85 for the A-D sample;
E is 32 and 1F is 10. Further, an impedance/gay/phase analyzer (4194A manufactured by Yokogawa Heuret Pub Card) was used for the measurement, and Table 2 shows the results.

Table 2 As shown in Table 2, the oxide ceramic superconductor with a fluorine-containing layer formed on its surface is significantly more stable than the comparative example in which a fluorine-containing layer is not formed. It can be seen that (environmental resistance) is improved. In particular, the RM-Cu-0 system, which is currently attracting attention due to its high critical temperature (Ihara and Yugoslavia of the National Institute of Electronics Technology, Agency of Industrial Science and Technology, and Djurek of the University of Zagreb, have suggested the possibility of room-temperature superconductivity). materials) have a great effect. Once room-temperature superconductivity is created, there will be more opportunities for exposure to the atmosphere, so greater stability (environmental resistance) will be required. At that time, the effects of the present invention will be very large.

Example-2 First, Dy (NOs)s, 8H*01I3a (
CH,Coo)*,Cu(CHsC00)H,O
Add to pure water and stir to disperse. Dy5BasC at this time
The ratio of u is 1:2:3. (In addition to Dy, Scs Y
1Lan than ido, etc.I ) Next, this liquid is dried by a dry spray method and simultaneously combusted to obtain a fine powder. Next, this fine powder is heated in an oxygen atmosphere at 900° C. for 8 hours, compression molded, and then sintered in an oxygen atmosphere at 920° C. to obtain a superconductor. Next, using the Ar-air jet method, Ar plasma is emitted into the air in the form of a jet, sprayed onto the superconductor to activate the superconductor surface, and then heated continuously at 300°C in a fluorine atmosphere for 2 hours. A layer containing fluorine is formed on the surface of the four superconductors. The reason why the surface layer is activated here is because the heat treatment in fluorine is performed at a low temperature. Although it is possible to form a fluorine-containing layer without surface activation at high temperatures, it may deteriorate the internal superconductor and it is difficult to optimize the processing conditions, so it is preferable to perform surface activation. .

The stability (environmental resistance) of the obtained sample was examined by the method of Example-1. The results are shown in Table 'M3.

As can be seen from Table 3, the stability (environmental resistance) was significantly improved as in Example-1 even when heat treated in a fluorine atmosphere. According to XPS analysis, the fluorine plasma treatment of Example 1 seems to be more preferable in terms of stability since the bonding ratio with other elements is higher.

〔Effect of the invention〕

As described above, according to the present invention, even an unstable oxide ceramic superconductor can be given stability (environmental resistance) by forming a fluorine-containing layer on its surface. In the future, if room temperature superconductivity becomes possible in this oxide ceramic super W14 material, the effect will be immeasurable. These superconducting materials are used, for example, in magnetic shielding, magnetic flux control of electron microscopes, magnetic lenses, speakers, video cameras, tape recorders, hard disks, magnetic heads of floppy disks, etc., 5QUID (high sensitivity magnetic sensor), optical switches, Jicocefunn element, superconducting motor, super? can be applied to conductive magnets, power transmission lines, etc.

that's all Applicant: Seiko Epun/Co., Ltd.

Claims (1)

[Scope of Claims] 1) A superconducting material comprising an oxide ceramic superconductor having a layer containing fluorine formed on its surface. 2) The oxide ceramic superconductor is a R-M-Cu-O superconductor (where R is one or a combination of rare earth elements including Sc and Y, and M
The superconducting material according to claim 1, wherein is Ca, Ba, Sr, or a combination thereof. 3) The superconducting material according to claim 1, wherein fluorine plasma treatment is used to form the layer containing fluorine.