JPH01316998A - Magnetic shielding material - Google Patents

Abstract

PURPOSE:To process a flexible superconductive substance coated sheet into an optional shape by a method wherein a sheet is coated with a superconductive substance thin film of bismuth, strontium, calcium, and copper through a chemical vapor phase deposition method. CONSTITUTION:A superconductive ceramic thin film is formed on a flexible sheet through a chemical vapor deposition method, using an evaporation source material which contains, at least, bismuth, strontium, calcium, and copper. In this manufacturing method, an alkoxide or a beta-diketon complex of bismuth, strontium, calcium, and copper is used as a raw material. The raw material of these four components is heated 5 until reaching to a temperature that the vapor pressure of the components is obtained, and an inert gas is introduced into a reaction vessel 8 as a carrier gas 6. Oxygen gas or gas containing oxygen is introduced into the reaction vessel 8 through a path 7 different from that of the raw material. A base flexible sheet 9, which makes a film deposit, is placed in the reaction vessel and moreover heated 10.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a magnetic shielding material in which a sheet is coated with bismuth, strontium, calcium, and copper-based superconducting materials.

(Prior art) Since superconducting materials exhibit complete diamagnetic properties, it is well known that when a superconducting material is placed in a magnetic field, magnetic flux cannot penetrate inside the superconducting material, and magnetic flux from the outside is distorted by the presence of the superconducting material. This is a fact, and by utilizing this property, by covering the magnetic field with superconducting material, the magnetic flux will not penetrate into the outside covered with superconducting material, so it is possible to obtain an external field that completely blocks magnetic force. Currently, oxide-based ceramic superconductors exhibiting various critical temperatures are being developed.

Among these oxide-based ceramic superconductors, Bi −(
Sr, Ca) -Cu=O is liquid nitrogen temperature (77K)
Applications to generators, power transmission cables, nuclear magnetic resonance spectrometers, Josephson element magnetic shielding materials, etc. are being considered as materials that can be used. However, in order to put these into practical use, it is necessary to make the superconductor into the required shape, and research is being carried out on making it into tapes, thin films, etc. Sputtering, vacuum evaporation, reactive evaporation, and the like have been studied as tape-forming and thin-film forming techniques, and oxide superconducting films have been obtained. However, these methods have problems in that the deposition rate is slow, it is difficult to deposit on large and large areas, they are not adaptable to long objects, and cannot be deposited on substrates with complex shapes.

(Problems to be Solved by the Present Invention) The present invention has been made in view of the above-mentioned problems, and it has a fast vapor deposition rate, can process large and large areas, and can deposit superconductors on long and complex shaped objects. The purpose is to completely block magnetic fields by providing a flexible sheet coated with a superconducting material produced by a method for producing a superconducting ceramic thin film.

(Means for Solving the Problems and Their Effects) In order to solve the above-mentioned problems, the present invention provides a chemical vapor deposition method using an evaporation source material containing at least bismuth, strontium, calcium and arsenic. This method employs a method of forming a thin film of superconducting ceramic on a flexible sheet.

More specifically, the production method of the present invention uses bismuth, strontium, calcium, and copper alkoxides or β-diketone complexes as raw materials. These four raw materials are heated to a temperature at which their vapor pressures are obtained, and an inert gas such as argon gas is introduced into the reaction vessel as a carrier gas. The carrier gas may be N2 or the like. Oxygen gas or a gas containing oxygen is introduced into the reaction vessel through a route different from that of the raw materials. A flexible sheet substrate for depositing a film is placed in a reaction vessel, and the substrate is further heated.

The substrate can be heated by placing a heater inside the reaction vessel and heating the substrate, or by heating the substrate from outside the reaction vessel. Furthermore, methods such as high frequency heating may be used. An inert gas containing oxygen gas or a gas containing oxygen and the vapor of an alkoxide or β-diketone complex containing each constituent element is introduced onto the substrate heated by any of the methods. The heating temperature of the substrate is a temperature above which the alkoxide or β-diketone complex is sufficiently decomposed and polymerized, and a temperature at which the substrate does not change. Preferably it is 700°C to 900°C. The pressure inside the reaction vessel is reduced pressure. The film thickness can be arbitrarily controlled by the deposition time, deposition temperature, raw material heating temperature, gas pressure, and carrier gas flow rate. Further, the composition of the superconductor can be controlled by the raw material heating temperature, precipitation temperature, gas pressure, and carrier gas flow rate. If the amount of oxygen in the superconductor needs to be adjusted or heat treated, it can be adjusted by controlling the oxygen partial pressure depending on the amount of oxygen introduced, and the heat treatment may be performed in air or oxygen. Furthermore, heat treatment may be performed within the reaction vessel during cooling of the superconductor after precipitation. The flexible sheet used as the base can be any woven or non-woven fabric such as carbon fiber cloth, alumina fiber, metal sheet, etc. If the flexible sheet lacks heat resistance, it can be made of silicon carbide, alumina magnesia, etc. It is used by coating with an oxidation-resistant film using a conventional method.

The superconductor film produced by the above manufacturing method is
The heating temperature of the raw material alkoxide or β-diketone complex, which is synthesized at a lower temperature than the temperature at which the sintered body is manufactured;
The composition can be controlled by the deposition temperature, gas pressure, and carrier gas flow rate, and the amount of oxygen or heat treatment can be performed in the same reaction vessel, and furthermore, it can be deposited on large substrates with large areas and complex shapes. .

(Example) The present invention will be described in detail with reference to FIGS. 1 to 3. FIG. 1 is an example of the manufacturing method according to the present invention. Bismuth, strontium, calcium, copper alkoxide or β-diketone complex, Bi (OC,H,)3.5r(
CzLqOz)z, Ca(C++H+qOz)z, C
u(C++H+9oz)z is placed in each of the raw material containers of 1.2.3.4 and heated by the heater 5. The bismuth alkoxide in container 1 is heated to 135°C, the strontium β-diketone complex in container 2 is heated to 220°C, the calcium β-diketone complex in container 3 is heated to 180°C, and the β-diketone complex in ill is heated to 130°C. . Each raw material part l, 2.3.
Argon gas is introduced into 4 as a carrier gas through an inert gas inlet 6 at a rate of 60 mA'/win. Also, 100 mJ/11 inch is introduced into the reaction vessel 8 from the oxygen gas introduction lower. The vapor of the alkoxide or β-diketone complex containing each constituent element is brought into the reaction vessel by a carrier gas.
is introduced onto the substrate, mixed with oxygen gas and introduced onto the substrate.

The base body 9 is heated to 820 to 83 by the heater 10 for heating the base body.
Heated to 0°C. The inside of the reaction vessel is under reduced pressure, and ITor
It is r. As described above, precipitation was carried out on the alumina thread woven soil for 1 hour. The thickness of the obtained membrane is 3-5 μm. FIG. 2 shows the X-ray diffraction pattern of the membrane peeled off from the woven fabric. Furthermore, FIG. 3 shows the temperature dependence of the resistivity of the film on the woven fabric. The film is a square product with a C-axis of 30.71, and contains a small amount of unidentified phase of CuO1, but its resistance decreases from around 110, and reaches zero at 78, indicating that the film is superconducting. It is clear that it is a body.

〔effect〕

The flexible superconducting material coated sheet obtained by the present invention can be processed into any shape and can seal magnetic flux in any shape, allowing a wide range of applications.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of an apparatus that can be used in the manufacturing method of the present invention;
FIG. 2 is a graph of the X-ray diffraction pattern of the film according to the example, and FIG. 3 is a graph of the resistivity temperature dependence of the film according to the example. In the figure: 1.2,3. L----- Raw material container, 5-- Raw material heating heater, 6----- Inert gas inlet, 7
----------oxygen gas inlet, 8-------inside the reaction vessel, 9---substrate, 10---substrate heating heater. Agent Patent Attorney Hideaki Kuwahara

Claims (1)

[Claims] A magnetic shielding material characterized by coating a sheet with a thin film of bismuth, strontium, calcium, and copper-based superconducting materials by chemical vapor deposition.