JPH0337102A - Production of oxide superconductor by metal organic chemical vapor deposition method - Google Patents

Abstract

PURPOSE:To stably supply a large amount of organic metal and to improve superconducting characteristics by adding tetrahydrofuran to an organic metal containing composition components of oxide superconductor and vaporizing the organic metal. CONSTITUTION:A transportation gas is introduced into a tetrahydrofuran tank 10 maintained at a fixed temperature, tetrahydrofuran 12 is sent to an organic metal tank 8 such as Ba-base heated to a fixed temperature to vaporize the Ba-based organic metal 9. Simultaneously, an organic metal 7 such as Y-base and an organic metal 9 such as Cu-base, etc., are vaporized. The gases of these organic metals 7, 8 and 9 are joined and sent with an oxidizing agent through a transportation gas passageway 1 to a reaction tube 3. A substrate 4 is heated by a heater 5 and an oxide superconductor is synthesized on a substrate 4 by heat reaction of the organic metal and the oxidizing agent.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is directed to the production of oxide superconductors using an organometallic chemical vapor deposition method to obtain oxide superconductors that can be applied, for example, to wires for superconducting coils that generate magnetic fields. The present invention relates to a method of manufacturing a body.

[Background Art 1] Recently, superconducting coils, magnetic shielding materials, high-frequency cavity resonators, etc. with low operating costs have been desired in fields such as magnetic levitation trains, nuclear magnetic resonance devices, and physical property research. In conventional superconducting coils, alloys with low critical temperature (Tc),
Superconducting coils are manufactured by winding a superconducting wire made of, for example, NbTi (Tc is about 10K) or an intermetallic compound, such as HbsSn (Tc is about 18K), around a coil frame. ) was being driven. For this reason, the cost required for cooling is high and the system is complicated. However, in 1987, an oxide superconductor with a very high Tc that exhibits superconductivity at liquid nitrogen temperature (77 K) was discovered, indicating the possibility of using superconducting coils at liquid nitrogen temperature. This superconductor is an oxide having a composition represented by YBazCusO)'.

This is usually produced by mixing Y2O5, BaC0, and CuO powders, molding, and then sintering heat treatment. Regarding the technology in this field, for example, see the magazine (Physical Review), Vol. 58 (1987), p. 908.
~p, 9101.

Superconducting wires used in superconducting coils are required to have a high critical current density (Jc). Furthermore, the superconducting wire used in conventional superconducting coils is required to be a long continuous wire and to have stable and excellent superconducting properties in the longitudinal direction.

However, since the oxide superconductor with a high Tc is a ceramic, it is very fragile, and it is difficult to make a long continuous wire using the above-mentioned sintering method.

On the other hand, if this material can be synthesized into a thick film at high speed by chemical vapor deposition (CVD), it will also be possible to manufacture wire rods. Therefore, attempts have been made to synthesize oxide superconductors by the CVD method using organic metals as raw materials. In this metal organic chemical vapor deposition method (MOCVD method), an organic metal is heated and vaporized to a gaseous state, and transported to a reaction part by a transport gas to synthesize an oxide superconductor mainly through a thermal reaction. Regarding the conventional technology in this field, for example, please refer to the journal (Journal of the Japanese Society of Applied Physics (J, Jpn, ^pp1
．． Phys,) Volume 27 <1988) p, 1265-p,
12671.

[Problems to be Solved by the Invention] In the conventional MOCVD method for manufacturing oxide superconductors, organic metals are vaporized by heating and supplied to the CVD reaction part in a gaseous state. is very difficult to vaporize, and it decomposes when the heating temperature is raised to increase the amount of vaporization, making it impossible to stably transport a large amount of raw material to the reaction section. For this reason, the synthesis speed is extremely slow, making it impossible to form a thick film necessary for making wire rods, which has been a major obstacle to making wire rods.

This invention was made to solve the above-mentioned problems. By stably supplying a large amount of organic metal, the synthesis rate can be dramatically increased, and a thick film-like oxide with excellent superconducting properties can be produced. The object of the present invention is to obtain a method for producing an oxide superconductor using an organometallic chemical vapor deposition method capable of obtaining a superconductor.

[Means for Solving the Problems] A method for producing an oxide superconductor by an organometallic chemical vapor deposition method according to the first aspect of the present invention is a method for producing an oxide superconductor using an organometallic chemical vapor deposition method according to the first aspect of the present invention. Oxide superconductivity is formed on the substrate through a process in which tetrahydrofuran is added to and vaporized, and these vaporized organic metals are transported to the reaction section by a transport gas, and a chemical reaction between the transported organic metals and the oxidizing agent occurs in the reaction section. It consists of a process of synthesizing the body.

Further, a method for producing an oxide superconductor by organometallic chemical vapor deposition according to the second invention includes blowing a transport gas into the container containing tetrahydrofuran according to the first invention,
Transport the tetrahydrofuran to a container containing the heated organometal and add the tetrahydrofuran to the heated organometal.

Furthermore, the method for producing an oxide superconductor by the organometallic chemical vapor deposition method according to the third invention is such that the organometallic material is placed in the container containing tetrahydrofuran at 120 to 20°C in the first and second inventions. The container is maintained at 100-300°C.

[Function] In the first aspect of the present invention, by carrying out a certain process, the organic metal can be stably transported to the reaction part in large quantities, dramatically increasing the synthesis rate and improving superconducting properties. A thick film-like oxide superconductor with excellent properties can be obtained.

Moreover, in the second invention, by transporting tetrahydrofuran between fixed containers, the manufacturing operation can be performed easily and stably.

Furthermore, in the third invention, an oxide superconductor with excellent superconducting properties can be obtained by selecting the temperatures of tetrahydrofuran and the organometallic within certain ranges.

[Example] This invention will be described below using a typical YBa
The zCu*Oy-based oxide superconductor will be explained.

FIG. 1 shows a reaction apparatus used in an embodiment of the present invention, and in the figure, a transport gas flow path (1), an oxidant transport path (2
) A reaction tube (3) containing a substrate (4) is placed in a circuit and heated by a heater (5).

(6) is an exhaust port. The transport gas flow path (1) includes a Y-based organometallic tank (7), a Ba-based organometallic tank (8), and a Cu
system organometallic tank (9), and further a tetrahydrofuran tank (1
0) is placed.

In the tetrahydrofuran tank (10), as shown in FIG. 2, tetrahydrofuran (12) is stored in a constant temperature bath (11) connected to a transport gas flow path (1>).

Next, the manufacturing method will be specifically explained. By blowing the transport gas into the tetrahydrofuran tank (10) maintained at a constant temperature, the tetrahydrofuran (12) is transported to a Bih-based organometallic tank (8) heated to a constant temperature,
The Ba-based organic metal is vaporized. At the same time, Y-based organometallic gas and Cu-based organometallic gas are respectively vaporized from Y-based organometallic (7) and Cu-based organometallic (9) heated to a constant temperature, and these are combined into a transport gas flow path ( The substrate (4>) placed inside the reaction tube (3) is then transported to the reaction tube (3) together with the oxidizing agent through the heater (5>
The oxide superconductor was synthesized on the substrate through a thermal reaction between the transported organic metal and the oxidizing agent. After heating for 30 minutes, the atmosphere was made into an oxygen atmosphere at atmospheric pressure and cooled to a temperature of 10-100 m.
A Ba2Cu, Oy-based oxide superconductor was obtained. The synthesis rate at this time was 20 sims/hour.

The tetrahydrofuran tank was maintained at an appropriate temperature within the range of -20 to 20°C, argon gas was used as the transport gas, and the flow rate was 10 to 100 cc/min, and oxygen gas was used as the oxidizing agent, and the flow rate was 50 to 100 cc/min. It was 100cc/min. In addition, Y, Da, etc. are used as organic metals as raw materials.

Y(DPM), which is a β-diketone complex of Cu, OIL
(DPM) 2 and Cu (DPH) were used in the 8 reaction tubes (3) in which these were kept at an appropriate temperature in the range of 100 to 300°C.The degree of vacuum inside was 1 to 10 torr.
The substrate (4) was a single crystal of MgO and 5rTiO1, and the temperature of the substrate (5) was an appropriate temperature in the range of 300 to 900°C.

In addition, for comparison, when synthesis was performed under the same synthesis conditions without adding tetrahydrofuran, which is the conventional method, 30
A YBazCulOy-based oxide superconductor with a film thickness of 0.1 pm was obtained by synthesis. The synthesis rate at this time is 0.2pm
/ It was time.

As mentioned above, the reason why the synthesis rate became extremely fast by adding tetrahydrofuran is that tetrahydrofuran reacts with the organic metal and produces a substance that easily vaporizes on the surface, thereby stabilizing a large amount of the organic metal. This is thought to be due to the fact that they can now be transported.

Next, the temperature dependence of the electrical resistance of the obtained superconductor was measured, and Te was evaluated. According to this, the Tc of the oxide superconductor produced by the method of the present invention was 84, while that of the oxide superconductor produced by the conventional method was as low as 58. In addition, as a result of measuring Jc at liquid nitrogen temperature, the TC of the oxide superconductor made by the method of this invention was 1000A/a+*'', but the TC of the oxide superconductor made by the conventional method was 1000 Therefore, superconducting current could not be passed.In this way,
According to the method of this invention, the synthesis speed is 100 times faster than before.
It was twice as fast, a thick film-like oxide superconductor was easily obtained, and both Tc and Jc were significantly improved.

In addition, in the above example, the case where tetrahydrofuran was added to the Ba-based organic metal, which is the most difficult to vaporize, was described, but adding it to the Y-based organic metal and/or the Cu-based organic metal also has the effect of further speeding up the synthesis rate. There is. In addition, Y, which was used in the above example as a raw material organometallic,
In addition to Ba and Cu DP14 series, Y(IF^)1,
Similar effects can be obtained by using Ba(IF^)2 and Cu()IF^)2. Regarding HFA series, Ba(!(F
^) It is most effective to add it to 2. The above manufacturing method is based on YBaCuO, but the raw materials include Bi, S
By appropriately combining r-Ca, Cu, Pb, Ti, and Ba-based organic metals, B i Pb5r
Similar effects can be obtained with intra-system conductor superconductors such as CaCuO-based superconductors and TiBaCaCuo-based superconductors.

[Effects of the Invention] As described above, according to the first aspect of the present invention, there is a step of vaporizing an organic metal containing each compositional component of an oxide superconductor by heating it, and a step of vaporizing the vaporized organic metal with a transport gas. In a method for manufacturing an oxide superconductor, the oxide superconductor is synthesized on a substrate by a chemical reaction between the organic metal transported and the oxidizing agent in the reaction section. By adding tetrahydrofuran to at least one of the organic metals,
Since the organic metal is transported stably and in large quantities, the synthesis rate is extremely fast, and therefore thick film-like oxide superconductors with excellent superconducting properties such as Tc and Jc can be efficiently manufactured. It has the effect of

Furthermore, according to the second invention, a transport gas is blown into a container containing tetrahydrofuran to transport it to a container containing a heated organic metal, and tetrahydrofuran is added to the heated organic metal, so that the above-mentioned effects can be achieved. In addition, manufacturing operations are easy and stable.

Furthermore, according to the third invention, by maintaining the container containing tetrahydrofuran at -20 to 20°C and the container containing the organic metal at 100 to 300°C, and selecting these temperatures appropriately. In addition to the above-mentioned effects, there is the effect that even more excellent superconducting properties can be obtained.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of a reaction apparatus for explaining one embodiment of the present invention, and FIG. 2 is a front sectional view of the tetrahydrofuran tank in FIG. 1. (1)... Transport gas flow path, (2)... Oxidizer transport path, (3>... Reaction tube, (4)... Substrate, (5)...
・Heater, (6>...Exhaust port, (7>...Y-based organometallic tank, (8)...Ba-based organometallic tank, (9>...
・Cu-based organometallic bath, (10)...Tetrahydrofuran bath, (11)...Thermostatic bath, (12>...Tetrahydrofuran. In each figure, the same reference numerals indicate the same or equivalent parts. 4 : Substrate 7.8, 9 : Ikutsuki f-group layer 10 : Tetrahydrofura diagram

Claims (3)

[Claims] (1). a step of vaporizing an organic metal containing each compositional component of the oxide superconductor by heating; a step of transporting the vaporized organic metal to a reaction part by a transport gas;
A method for producing an oxide superconductor comprising the step of synthesizing the oxide superconductor on a substrate by a chemical reaction between the organic metal transported in the reaction section and an oxidizing agent, wherein at least one of the heated organic metals 1. A method for producing an oxide superconductor by an organometallic chemical vapor deposition method, the method comprising the step of adding tetrahydrofuran to the oxide superconductor. (2). The organometallic chemical vapor phase according to claim 1, wherein the tetrahydrofuran is added to the heated organometallic by blowing a transport gas into a container containing tetrahydrofuran and transporting the tetrahydrofuran to a container containing the heated organometal. A method for producing an oxide superconductor using a vapor deposition method. (3). -20~2 container containing tetrahydrofuran
The method for producing an oxide superconductor by the organometallic chemical vapor deposition method according to claim 1 or 2, wherein the temperature is maintained at 0°C and the container containing the organometallic is maintained at 100 to 300°C.