JPH01278416A - Production of precursor substance for oxide superconductor - Google Patents

Abstract

PURPOSE:To improve the Tc and Jc of a superconductor obtained from a precursor substance by restricting the feeding ratio of hydrogen gas to oxygen gas for flame-generation in the production of a precursor of a Y-Ba-Cu-O oxide superconductor using a spray thermal reaction process. CONSTITUTION:Compounds each containing the elements such as Y, Ba, Cu, etc., are weighed at ratios of Y:Ba:Cu=1:2:3 and dissolved in a solvent. The solution is atomized and introduced into a flame. The atomized mist is heated with the flame to form a precursor substance of an oxide superconductor expressed by the chemical formula Y1Ba2Cu3Ox. The feeding ratio of the hydrogen gas to the oxygen gas in the generation of the flame for heating the mist is maintained to 2.5-3.5 volume of oxygen gas based on 1 volume of hydrogen gas.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for producing a Y-Ba-Cu-0 based oxide superconductor precursor.

[Conventional technology and its issues]

In recent years, Y + B az Cu s O? −δ(δL
:An oxide superconductor consisting of rare earth elements, alkaline earth metals, copper, and oxygen with a t of 0.2 to 0.31 has been discovered. These oxide superconductors are much more economical than conventional metal superconductors that exhibit superconductivity at liquid He temperatures because they become superconducting above the liquid Nt temperature, and their use in various fields is being considered.

By the way, the above-mentioned oxide superconductors are brittle and cannot be plastically worked like metal materials, and powder metallurgy is mainly used to process them into wire rods, etc. For example, y, o, 3aC
Raw material powder of Oz and CuO is calcined, and this is pulverized and classified to form calcined powder, and this powder is coated and molded onto a substrate.
Alternatively, it is filled into an Ag pipe, etc. and stretched, and then this is Ot.
A method of forming an oxide superconducting molded body by heating and sintering in a containing atmosphere is used.

However, in the production of the above calcined powder, it takes a long time to crush and classify the calcined body, and the resulting calcined powder has large variations in particle size, and furthermore, impurities are mixed in from the crusher such as a ball mill. There were various problems such as.

For this reason, a spray heating reaction method has been proposed in which a raw material for an oxide superconductor is dissolved in a solvent, the solution is atomized, and the atomized solution is supplied into a flame for a heating reaction to produce a precursor for an oxide superconductor. ing.

This method has the advantage that a highly pure precursor can be obtained because the reaction time is very short and there is almost no contact with containers or jigs.

By the way, in the case of the Y-Ba-Cu-0 system, in the above-mentioned spray heating reaction method, each element of Y, Ba, and Cu is dissolved in an atomic ratio of 1:2:3 in each droplet constituting the atomized body. The above elements YSBa and Cu are heated by a flame and react with 0□ in the droplet or in the atmosphere to form oxide superconductor precursors represented by the chemical formulas Y, Ba, and CUBah. This is the result.

The oxide superconductor precursor material is subjected to a prescribed heat treatment in an oxygen-containing atmosphere, and Y+BazCu*0, -δ(δ
= 0.2~0.3), and superconducting properties are obtained when the atomic ratio of the constituent elements Y, Ba, and Cu is I:2:3, respectively. It is the one most commonly expressed.

However, the oxide superconductor precursor produced by the spray heating reaction method often becomes a composite oxide lacking or in excess of rare earth elements such as Y, and even if such a precursor is heat-treated in an oxygen-containing atmosphere, the There was a problem that superconducting properties could not be obtained.

[Means and effects for solving the problem] The present invention has been made as a result of intensive research in view of the above circumstances, and has been developed to produce a flame during the production of a Y-Ba-Cu-0 based oxide superconductor precursor by a spray heating reaction method. H2 gas and 0. It was found that the amount of Y in the produced precursor is greatly influenced by the gas supply ratio, and as a result of further research on this point, the method of the present invention was achieved.

That is, the present invention involves weighing compounds each containing elements such as Y, Ba, and Cu at a ratio of Y:Ba:Cu of 11:3, dissolving each in a solvent, atomizing this solution, and supplying it to a flame. Then, this atomized material is heated by the above flame to produce Y+Bax
In a method for producing a precursor of an oxide superconductor represented by the chemical formula CusC)+, the supply ratio of hydrogen gas and oxygen gas for generating a flame for heating the atomized body is set to 1 volume of hydrogen gas to 1 volume of oxygen gas. This is a method for producing an oxide superconductor precursor characterized by having a capacity of 2.5 to 3.5.

In the present invention, Y 1 B az Cu z Oq-
Compounds containing each of the constituent elements of the oxide superconductor represented by the chemical formula δ include, for example, acetates, nitrates, halides, or organometallic compounds of Y, Ba, and Cu, respectively.

In the present invention, the method for atomizing the above compound is as follows:
For example, a method is used in which each of the above-mentioned compounds is dissolved in a solvent such as water and atomized using an ultrasonic nebulizer or the like.

As a method for continuously supplying the above-mentioned atomized material to the flame, it is preferable to convey the atomized material in a carrier gas such as air, 0□, N2, Ar, etc., since the amount of the atomized material to be supplied can be easily controlled.

In the present invention, the flame fuel is H2 gas, and the combustion supporting gas is 0. The reason why gas is used and the supply amount of both is limited to 2.5 to 3.5 in terms of Ox/Hz capacity ratio is that outside the above range, the generated precursor will not contain the specified amount of Y. be. That is, as shown in FIG. 2, among the Y, Ba, and Cu atoms contained in the precursor, the atomic ratio of Ba and Cu is O, /H.

It does not change at all depending on the capacitance ratio of O!, but the atomic ratio of Y changes greatly, and O! /H! is within the range of 2.5 to 3.5, the atomic ratio of Y is 0.9 to 1.1, which is a value close to 1.

The reason why the atomic ratio of Y changes greatly depending on the Ox/Hz capacity ratio in the above is not clearly understood, but it may be because the flame temperature and the amount of excess oxygen in the flame affect the amount supplied to the precursor. Conceivable.

Y-Ba produced by heating with flame in the present invention
-Cu-0 based superconductor precursor is Y18a, Cu5O
This composite oxide has a composition of This is what is done.

In the present invention, the flame temperature is set by the supply amount of N2 gas and Oz gas, but it fluctuates depending on the supply amount of the atomized material, which is the raw material, so it is preferable to constantly measure and control it.

〔Example] The present invention will be explained in detail below using examples.

Example 1 FIG. 1 is an explanatory diagram showing an example of a spray heating reaction apparatus used to carry out the method of the present invention.

The spray heating reaction device includes an ultrasonic nebulizer 2 that atomizes a solution 1 in which a raw material compound is dissolved, a carrier gas pipe 5 that conveys the raw material atomized body 3 to a burner 4, and an oxide superconductor heated and reacted by the burner 4. It consists of a 0.5 mm thick YSZ (Y-stabilized zirconia) type substrate 7 on which a body precursor 6 is deposited.

In this example, Y (CH3COO)s is used as a compound containing the constituent elements of the Y-Ba-Cu-0 superconductor.
・4 HzOlBa (CH,C00)z・Ht.

and Cu (CHlCOO)z・H2O, each compound was weighed so that the molar ratio of Y:Ba:Cu was 1:2:3, and this was added to water as 'f 1 Ba z Cu
s at a concentration of 0.04 mol/l, this solution 1 is placed in a container in an ultrasonic nebulizer 2, and ultrasonic vibration is applied to it to suspend the solution 1 in the form of a mist. Transfer the mist 3 to the carrier gas vibe 5 with 0.617 N2 gas.
It was conveyed to the burner 4 by flowing at a flow rate of s+in.

This burner 4 has a quadruple pipe structure, and the NZ gas containing the raw material atomized material 5 flows from the first nozzle in the center pipe, the Ht gas serving as fuel flows from the second nozzle on the outer periphery, and the burner flows from the third nozzle on the outer periphery. A "gas" for sealing to protect the tip from flame heat, is designed to eject combustion supporting gas from the fourth nozzle in the outermost layer, and N2 gas ejected from the second nozzle and the fourth A flame 9 is generated by combustion-supporting Ot gas ejected from a nozzle, and the raw material atomized material 3 is heated in the flame 9 to produce a Y-Ba-Cu-0 superconductor precursor at 0.15 g/ll1in. generated at a speed of
The produced Y-Ba-Cu-0 based superconductor precursor 6 was deposited as a film 8 having a thickness of 0.1 m on a substrate 7 disposed in front of the burner 4 and moving in the direction of the arrow.

In the above, the N2 gas and O2 gas that generate the flame 9 were supplied at various supply ratios to produce the Y-Ba-Cu-0 based superconductor precursor 6.

Each of the Y-Ba-Cu-0 superconductor precursors thus obtained was heated with 950'C2OH in an oxygen stream and then slowly cooled from 950°C at a rate of 2°C/min to form superconductors. Body weight, Y amount, T, and Jc were measured.

The results are shown in Table 1 along with the main manufacturing conditions.

As is clear from Table 1, the method of the present invention (1 to
In case 3), the atomic ratio of Y was within the range of 0.95 to 1.05, and both Tc and Jc showed high values.

On the other hand, in the comparison method (4, 5), the Y atomic ratio significantly deviated from 1.0, resulting in low Tc and Jc values.

In the above example, the Y-Ba-Cu-0 superconductor precursor adhered to the substrate was heat-treated as it was to form a superconductor, but the adhered material was scraped off from the substrate, crushed and classified, and compacted. A similar effect can be obtained even if heat treatment is performed.

〔effect〕

As described above, according to the method of the present invention, Y-B represented by the chemical formula of Y+Batcusox containing a predetermined amount of Y
Precursors of a-Cu-0-based superconductors are easily produced,
The Y-Ba-Cu-0 superconductor obtained by subjecting this to a predetermined heat treatment in an oxygen-containing atmosphere has excellent properties such as TCSJc, and has a remarkable effect industrially.

[Brief explanation of the drawing]

Figure 1 is an explanatory diagram showing an example of a spray heating reactor used to carry out the method of the present invention, and Figure 2 is an illustration of the Ox/Hz capacity ratio of the flame and the atomic ratio of Y, Ba, and CU in the precursor. It is a figure showing a relationship. 1...t'jI liquid, 3... Raw material mist, 6.
...Y-Ba-Cu-0 based superconductor precursor.

Claims (1)

[Claims] A compound containing each of elements such as Y, Ba, and Cu is Y:
Ba:Cu was weighed in a ratio of 1:2:3 and dissolved in a solvent, this solution was atomized and supplied into a flame, and this atomized body was heated by the flame to produce Y_1Ba_2Cu_
In a method for manufacturing a precursor of an oxide superconductor represented by the chemical formula 3O_x, the supply ratio of hydrogen gas and oxygen gas for generating a flame for heating the atomized body is 1 volume of hydrogen gas to 2.0 volume of oxygen gas. A method for producing an oxide superconductor precursor characterized by having a capacity of 5 to 3.5.