KR101719266B1 - Superconductor, superconducting wire, and method of forming the same - Google Patents

Abstract

The superconductor comprises a first step of heat treating a superconducting precursor comprising rare earth, barium and copper to form a liquid rare earth-copper-barium oxide, the rare-earth copper-barium oxide epitaxially grown from the liquid rare earth- A second step of forming a first superconductor of oxide, and a third step of forming a second superconductor of rare earth-copper-barium oxide by heat-treating the first superconductor, The heat treatment is performed in an atmosphere in which the rare earth-copper-barium oxide does not have a liquid phase.

Description

TECHNICAL FIELD [0001] The present invention relates to a superconductor, a superconducting wire, and a method of forming a superconductor.

The present invention relates to a superconductor.

Superconductors can dissipate a large amount of current due to the loss of electrical resistance at low temperatures. Recently, studies on a thin buffer layer having a biaxially oriented texture or a second generation high temperature superconductor (Coated Conductor) forming a superconductor on a metal substrate have been actively studied. Second generation high-temperature superconductors can be applied to various fields. For example, a wire using a second-generation high-temperature superconductor has a current-carrying capacity per unit area that is far superior to a general metal wire. The second-generation high-temperature superconductor-based wire rod can reduce the power loss of electric power equipment and can be used in fields such as MRI, superconducting magnetic levitation train, and superconducting propulsion vessel.

An object of the present invention is to provide a superconductor containing magnetic flux fixing points.

Another object of the present invention is to provide a superconducting wire containing magnetic flux fixing points.

Yet another object of the present invention is to provide a method of forming a superconductor containing magnetic flux fixing points.

A method of forming a superconductor is provided. The method includes providing a first superconducting precursor comprising rare earth, barium and copper; Performing a pre-heat treatment process on the first superconducting precursor to form a first superconductor in which rare-earth-copper-barium oxide is epitaxially grown; And subjecting the epitaxially grown first superconductor to a post-heat treatment process to form a second superconductor. Wherein the pre-heat treating step comprises: heat treating the first superconducting precursor at a first temperature and a first oxygen partial pressure to form an amorphous second superconducting precursor; Heat treating the amorphous second superconducting precursor at the first temperature and a second oxygen partial pressure higher than the first oxygen partial pressure to form a liquid third superconducting precursor containing rare earth oxide grains; And heat treating the liquid third superconducting precursor at a second oxygen partial pressure and a second temperature lower than the first temperature to form the first superconductor having the epitaxial growth and the copper oxide grains in the first epitaxially grown superconductor, Lt; / RTI > The post-annealing process may include annealing the epitaxially grown first superconductor at a third oxygen partial pressure higher than the second oxygen partial pressure and a third temperature lower than the first temperature and higher than the second temperature, And forming c-axis aligned copper oxide plates in the grown first superconductor.

As an example, the first superconducting precursor may be heat treated to the first oxygen partial pressure of 10 ^-6 to 10 ^-3 Torr and the first temperature of 860 ° C.

As an example, the amorphous second superconducting precursor may be heat treated to the second oxygen partial pressure of 10 ^-2 to 10 ^-1 Torr and the first temperature of 860 ° C.

As an example, the liquid third superconducting precursor may be heat treated to the second oxygen partial pressure of 30 mTorr and the second temperature of 740 캜 or lower.

As an example, the epitaxially grown first superconductor may be heat treated to the third oxygen partial pressure of 300 mTorr and the third temperature of 800 ° C.

In one example, the rare earth-copper-barium oxide of the epitaxially grown first superconductor may be formed from the rare earth oxide grains.

In one example, the second superconductor may contain a laminate of rare earth oxide particles and copper oxide dispersed therein.

For example, the rare earth oxide is RE ₂ O ₃ , the first superconductor has an image of RE _{1 + x} Ba _{2 - x} Cu ₃ O ₇ -δ, the second superconductor is RE _{1+ y} Ba _{2 - y} Cu ₃ Y, and Y have the phases of O _{7 -δ} , 0 <x <1, x> y, and 0 <δ <1, and RE is La, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, , And at least one of the lanthanide elements including Lu, or Y.

In one example, the second superconductor may further contain RE ₂ BaCuO ₅ .

In one example, the rare earth-copper-barium oxide is formed on a tape-shaped substrate, and the substrate may include an oxide buffer layer formed on the metal substrate having the texture.

In one example, the rare earth oxide grains may be grown from the oxide buffer layer into the third superconducting precursor in the liquid phase.

According to the embodiments of the present invention, a superconductor having excellent crystallinity can be formed in a faster process. In addition, it is possible to easily form granular and / or laminated defects of rare earth oxides which can function as magnetic pinning centers in the superconductor. Further, the critical temperature Tc of the superconductor can be increased, and the critical current characteristic under the magnetic field can be improved.

1 is a flow chart illustrating a method of forming a superconductor according to embodiments of the present invention.
2A shows a phase diagram of GdBCO and an example of a pre-heat treatment process according to the present invention.
FIG. 2B shows an example of a phase diagram of GdBCO and a post-heat treatment process according to the present invention.
3 to 7 are cross-sectional views illustrating a method of forming a superconductor according to embodiments of the present invention.
8 to 10 are TEM images of an epitaxial superconductor formed according to embodiments of the present invention.
11 is an XRD of an epitaxial superconductor of rare earth-barium-copper oxide formed in accordance with embodiments of the present invention.
13A and 13B are TEM images of epitaxial superconductors after the post-annealing process and after the annealing process, respectively.
Figure 14 shows the critical temperature (Tc) characteristics of a superconductor formed in accordance with embodiments of the present invention.
Figure 15 shows the critical current (Jc) characteristics under an externally applied magnetic field of a superconductor formed according to embodiments of the present invention.
16 to 19, an example of an apparatus for forming a superconductor according to the concept of the present invention will be schematically described.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the present invention is not limited to the embodiments described herein but may be embodied in other forms. Rather, the embodiments disclosed herein are provided so that the disclosure can be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. In addition, since they are in accordance with the preferred embodiment, the reference numerals presented in the order of description are not necessarily limited to the order.

In the following embodiments, GdBCO is described as a superconductor, but the present invention is not limited thereto. GdBCO means RE _{1 + x} Ba _{2 - x} Cu ₃ O _{7 -δ} (0 <x <1, 0 <δ <1). Will be described in more detail below.

1 is a flow chart illustrating a method of forming a superconductor according to embodiments of the present invention. Referring to FIG. 1, a method of forming a superconductor according to embodiments of the present invention includes a step (S10) of forming a superconducting precursor film on a substrate, a pre-annealing process (S20) of forming an epitaxial superconductor, And a post-annealing process (S30) that improves the performance of epitaxially grown superconductors.

2A shows a phase diagram of GdBCO and an example of a pre-heat treatment process according to the present invention. FIG. 2B shows an example of a phase diagram of GdBCO and a post-heat treatment process according to the present invention.

Referring to Figs. 2A and 2B, the first region Rl may be in a state at an oxygen partial pressure of about 10 < ^-2 &gt; Torr or less and a temperature of 850 DEG C or less. The second region R2 may be in an oxygen partial pressure of about 10 &lt; ^-1 &gt; to 10 &lt; ^-2 &gt; Torr or less and at a temperature of 850 DEG C or higher. The third region R3 may be in a state of higher oxygen partial pressure than the first region R1 and the second region R2. The third region R3 and the first and second regions R1 and R2 may be separated by a boundary line I. [ In the first region R1, GdBCO can be understood to have Gd ₂ O ₃ , GdBa ₆ Cu ₃ O _{7 -δ} (0 <δ <1) and a liquid phase. Here, the liquid phase is a liquid state containing Ba, Cu and O as main components and Gd dissolved therein. In the second region (R2), GdBCO may be understood to have a Gd ₂ O ₃ and liquid phases. In the third region R3, GdBCO can be understood to have an epitaxial GdBCO.

3 to 7 and 12 are cross-sectional views illustrating a method of forming a superconductor according to embodiments of the present invention. Referring to Figs. 2 to 7, a method of forming a superconductor according to embodiments of the present invention will be schematically described.

Referring to Fig. 3, a substrate 10 is provided. The substrate 10 may have a biaxially aligned textured structure. The substrate 10 may be, for example, a metal substrate. The metal substrate may be a cubic system metal such as Ni-Ni alloy (Ni-W, Ni-Cr, or Ni-Cr-W) subjected to rolling heat treatment, stainless steel, silver, silver alloy or Ni-silver composite. The substrate 10 may be in the form of a tape for plate or wire.

An IBAD layer 20 may be formed on the substrate 10. IBAD layer 20 may include a diffusion preventive film which are sequentially stacked (for example, Al ₂ O _3), a seed layer (e.g., Y ₂ O _3), and the MgO film. The IBAD layer 20 is formed by the IBAD method. An epitaxially grown homoepi-MgO (MgO) film may be further formed on the MgO film. The buffer layer 30 may be formed on the IBAD layer 20. [ Buffer layer 30 is LaMnO _3, LaAlO _3, CeO ₂ or SrTiO ₃ . &Lt; / RTI &gt; The buffer layer 30 may be formed by a sputtering method. The IBAD layer 20 and the buffer layer 30 prevent the reaction between the substrate 10 and the superconducting material thereon and transmit the crystallinity of the biaxially oriented texture.

1 and 4, a superconducting precursor 40 is formed on the buffer layer 30. (S10) The superconducting precursor 40 is formed of, for example, at least one of rare earth elements RE For example, Gd), copper (Cu), and barium (Ba). The rare earth element RE can be understood to include yttrium (Y) and lanthanide group elements. The lanthanide elements include La, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu and the like as is well known.

The superconducting precursor 40 may be formed in various ways. The superconducting precursor 40 may be formed by, for example, RE-co-evaporation, PLD, sputtering, CVD, Metal Organic Deposition (MOD) or sol- . The formation of the superconducting precursor 40 is not limited to the specific method described above.

As one method, the superconducting precursor 40 may be formed by an evaporation method. The evaporation method is a method of irradiating an electron beam to a vessel containing at least one of rare earth elements (RE), copper (Cu) and barium (Ba), and providing a metal vapor on the substrate to deposit a superconducting precursor can do.

Alternatively, the superconducting precursor 40 may be fabricated by Metal Organic Deposition (MOD). (RE) -acetate, barium (Ba) -acetate and copper (Cu) -acetate are dissolved in an organic solvent and subjected to evaporation distillation and redissolution- (Cu) and barium (Ba) is prepared. The metal precursor solution is applied onto the substrate.

Alternatively, the superconducting precursor 40 may be powders comprising at least one of the rare earth elements RE (e.g., Gd), copper (Cu), and barium Ba.

Thereafter, a pre-annealing process (S20) for forming an epitaxial superconductor may be performed. Hereinafter, the pre-heat treatment process will be described in detail.

2 and 5, the substrate 10 on which the superconducting precursor 40 is formed is subjected to a first heat treatment. The first heat treatment may be performed under an oxygen partial pressure of 10 ^-3 Torr to 10 ^-6 Torr. The oxygen partial pressure of the first heat treatment may be, for example, about 10 ^-5 Torr. The temperature of the first heat treatment may be raised to 800 to 1000 占 폚 (for example, about 860 占 폚). The first heat treatment may be performed along the path IA of FIG. 2A. By the first heat treatment, an amorphous superconducting precursor 40 can be formed on the substrate 10.

2 and 6, the substrate 10 on which the amorphous superconducting precursor 40 is formed is subjected to a second heat treatment. The second heat treatment may be performed at a temperature of 800 to 1000 占 폚 (e.g., about 860 占 폚). The second heat treatment can be performed by increasing the oxygen partial pressure in the first heat treatment. The oxygen partial pressure during the second heat treatment may be increased, for example, from 10 ^-5 Torr to 10 ^-2 Torr to 10 ^-1 Torr (e.g., 30 mTorr). The second heat treatment can be performed along the path IB in Fig. 2A. By the second heat treatment, the amorphous superconducting precursor 40 turns into a liquid superconducting precursor 41, and a rare earth oxide (for example, Gd ₂ O ₃ ) can be formed in the liquid superconducting precursor 41. The rare earth oxide 43 may be dendritely grown from the buffer layer 30 on the substrate 10. That is, by the second heat treatment along the path IB, the liquid superconducting precursor 41 containing the rare earth oxide 43 is formed.

2 and 7, the liquid superconducting precursor 41 containing the rare earth oxide 43 is subjected to the third heat treatment. The third heat treatment may be a cooling process that reduces the temperature under an oxygen partial pressure (e.g., 100 mTorr) of approximately 10 ^-2 Torr to 10 ^-1 Torr. The cooling rate may be 1 deg. C / hr or more (approximately 5 deg. C / 1 hr). The third heat treatment may be performed along the path IC of FIG. 2A. By the third heat treatment, an epitaxial superconductor 45 of rare earth-barium-copper oxide is formed. The epitaxial superconductor 45 of rare earth-barium-copper oxide may be produced from the liquid superconducting precursor 41 while consuming the rare earth oxide 43. In this way, an epitaxial superconductor 45 having crystallinity in a very fast process can be formed. Epitaxial superconductor 45 is RE _{1+ x} Ba _{2 -} may have the phase of the _{x Cu 3 O 7 -δ (0} <x <1, 0 <δ <1).

At the same time, the size of the rare earth oxide 43 decreases and the rare earth oxide 43 changes into elongated grains. The grains of rare earth oxide 43 may have a size of about 1 탆 or less. In the epitaxy superconductor 45, grains of the rare earth oxide 43 as well as grains of the liquid residue 48 and the copper oxide 47 may be additionally generated. Another liquid residue 49 may remain on the upper surface of the epitaxial superconductor 45. The liquid residues 48 and 49 may be barium-copper oxide due to the liquid superconducting precursor 41 that has not changed to the epitaxial superconductor 45.

The grains 43, 47 produced in the epitaxial superconductor 45 may function as the flux fixation points of the superconductor. The width of the particles of the rare earth oxide 43 may be approximately several tens nm to 100 nm. The width of the particles of the rare earth oxide 43 may preferably be 100 nm or less.

8 to 10 are TEM images of an epitaxial superconductor 45 formed in accordance with embodiments of the present invention. 8 shows the epitaxial superconductor 45 formed on the substrate 10, the grains of the rare earth oxide 43 contained therein, and the liquid residues 48, 49. 9 and 10 show the grains of an epitaxial superconductor 45 and a rare earth oxide (e.g., Gd ₂ O ₃ ) 43 formed on a substrate 10. The width of the grains of the rare earth oxide 43 was approximately several tens nm.

11 is an XRD of a rare earth-barium-copper oxide epitaxy superconductor 45 formed in accordance with embodiments of the present invention. Fig. 11 shows the good crystallinity of the epitaxial superconductor 45 of rare earth-barium-copper oxide.

For the pre-heat treatment step S20, a method different from the above-described embodiments can be used. For example, the pre-heat treatment process may be performed along path IIA and path IIB in the state diagram of FIG. 2A. First, a first heat treatment along path IIA can be performed. The first heat treatment along the path IIA can be carried out under an oxygen partial pressure of, for example, 10 ^-2 to 10 ^-1 Torr. The temperature of the first heat treatment can be increased to about 800 ° C or more (for example, 850 ° C or more) at room temperature. The first heat treatment along the path IIA passes the boundary line I of the state diagram of FIG. 2A. As a result, a liquid superconducting precursor 41 containing the rare earth oxide 43 is formed (see Fig. 6). [

Next, a second heat treatment along path IIB may be performed. The second heat treatment along the path IIB may be a cooling process which reduces the temperature under an oxygen partial pressure of, for example, 10 ^-2 Torr to 10 ^-1 Torr (for example, 100 mTorr). Accordingly, the grains of the rare earth oxide 43 and the epitaxial superconductor 45 can be formed. The epitaxial superconductor 45 may have an image of RE _{1 + x} Ba _{2 -x} Cu ₃ O _{7 -δ} (0 <x <1, 0 <delta <1). (See Fig. 7)

The growth process of the epitaxial superconductor according to the above-described embodiments is similar to the liquid phase epitaxy (LPE).

After this, a post-annealing process may be performed to improve the performance of the epitaxially grown superconductor.

Referring to Figs. 2B and 12, the epitaxial superconductor 45 is post-heat treated. Post-heat treatment may be performed along path III. Post-heat treatment is performed in an atmosphere in which the epitaxial superconductor 45 does not have a liquid phase. For example, the post-heat treatment is more than 10 ^-3 Torr, an oxygen partial pressure of about 10 ^-2 Torr to a few Torr may be carried out at a temperature of 700 ~ 800 ℃ under (e. G., 300mTorr). By post-heat treatment, copper oxide (e.g., CuO or Cu ₂ O) 46 may be produced from the epitaxy superconductor 45. At the same time, the epitaxial superconductor 45 can be transformed into an RE _{1 + y} Ba _{2 - y} Cu ₃ O _{7 -δ} phase. Here, x> y. That is, copper oxide (for example, CuO or Cu ₂ O) can escape from the epitaxial superconductor 45 by post-heat treatment. These copper oxides 46 may be stacked plates aligned in the c-axis direction of the epitaxial superconductor 45. In other words, this copper oxide 46 is an REBaCuO compound (for example, RE _{1 + z} Ba _2-z Cu ₄ O ₇ -δ, 0 <z <1) having another phase with the epitaxial superconductor 45, . As a result, such copper oxide 46 may form stacking faults 46 in the epitaxial superconductor 45.

13A and 13B are TEM images of the epitaxial superconductor 45 after the post-annealing process and after the annealing process, respectively. 13A and 13B, after the post-annealing process, grains of rare earth oxide 43 dispersed in epitaxial superconductor 45 and stacking defects 46 parallel to the c-axis of GdBCO are produced Able to know.

Figure 14 shows the critical temperature (Tc) characteristics of a superconductor formed in accordance with embodiments of the present invention. (b) is a post-heat treatment for 5 minutes at 800 ° C under a pressure of 300 mTorr, (c) is a post-heat treatment for 10 minutes at 800 ° C under a pressure of 300 mTorr, In one case, (d) shows temperature-resistance graphs in the case of post-heat treatment at 800 캜 for 30 minutes under a pressure of 300 mTorr, and (e) in post-heat treatment at 800 캜 for 120 minutes under a pressure of 300 mTorr do. As shown, the post-heat treatment increased the critical temperature Tc by about 4K.

Figure 15 shows the critical current (Jc) characteristics under an externally applied magnetic field of a superconductor formed according to embodiments of the present invention. (a) is a case where post-heat treatment is not performed, and (b) is a case where post-heat treatment according to the present invention is performed (for example, post-heat treatment at 800 캜 for 30 minutes under a pressure of 300 mTorr). The superconducting material was GdBCO. The measurement temperature was 77 K and the magnetic field strength was 1 Tesla (1T). The intensity of the magnetic field was constant and the critical current was measured while changing the direction of the magnetic field. In the figure, the magnetic field at an angle of 0 degrees is parallel to the surface of the superconducting wire , and 90 degrees is perpendicular to the surface of the superconducting wire The direction of the critical current of the superconductor according to the present invention, while varying (please check. PPT material is 90 degrees to the magnetic field is ab is in parallel geoteu. The plane) size of the critical current of (a) at least 50% The size (b) varied within approximately 20% depending on the angle. When a current over a critical current flows through the superconductor, the superconductor loses its superconducting characteristic. In a power device such as a motor or a generator, a magnetic field is generated by a current flowing in the power device, and the direction of the magnetic field is difficult to control. Therefore, the critical current of a superconductor is determined by the smallest value according to the angle. The superconductor according to the present invention is very advantageous for application to electric power equipment because the change of the critical current according to the angle is very small.

The superior property of such a superconductor is that rare earth oxide grains and stacking faults generated therein function as the flux fixation points of the superconductor.

2A and 2B show the state diagram of GdBCO, the specific oxygen partial pressure and the heat treatment temperature may be varied depending on the kind of the rare earth element RE.

The superconductor formed by the above-described method may be a superconductor formed as a film on the substrate 10. [ The above-described embodiments illustrate the formation of a superconducting film, but are not limited thereto. It will be appreciated that the heat treatment of the above embodiments can also be applied to bulk superconductors. For example, an amorphous rare earth-barium-copper oxide is prepared. The amorphous rare earth-barium-copper oxide may be changed into a rare-earth-barium-copper oxide having a single crystal structure through the above-described heat treatment process. The rare-earth-barium-copper oxide of the single crystal structure may include the rare earth oxide particles, barium-copper oxide particles, and stacking defects scattered and contained therein.

16 to 19, an example of an apparatus for forming a superconductor according to the concept of the present invention will be schematically described. The superconductor forming apparatus described with reference to FIGS. 16 to 19 is an example of the superconducting wire according to the present invention, and the concept of the present invention is not limited thereto.

Figure 16 schematically shows a device for forming a superconductor according to the present invention. 16, the apparatus for forming a superconductor includes a thin film deposition unit 100 for forming a superconducting precursor film on a substrate, a heat treatment unit 200 for heat-treating a substrate including a superconducting precursor film formed in the thin film deposition unit 100, And a substrate supply / recovery unit 300. A vacuum load 20 can be additionally provided between the thin film deposition unit 100, the heat treatment unit 200 and the substrate supply / recovery unit 300 so that the substrate can pass through and maintain a vacuum.

17 schematically shows a cross section of a thin film deposition unit 100 of the apparatus for forming a superconductor according to the present invention. 16 and 17, the thin film deposition unit 100 may include a process chamber 110, a REEL to REEL device 120, and a deposition member 130. Specifically, the process chamber 110 provides a space in which the deposition process for forming the superconducting precursor film on the substrate 10 is performed. The process chamber 110 includes a first sidewall 111 and a second sidewall 112 facing each other. The first side wall 111 is provided with a draw-in portion 113 connected to the substrate supply / recovery unit 300 and the second side wall 112 is provided with a draw-out portion 114 connected to the heat processing unit 200 do. The substrate 10 is drawn into the process chamber 110 from the wire rod supply / recovery unit 300 through the lead-in portion 113 and enters the heat treatment unit 200 through the lead-

The deposition member 130 may be provided under the reel-to-reel apparatus 120. Thereby providing a vapor of the superconducting material to the surface of the substrate 10. In one embodiment, the deposition member 130 may provide a superconducting precursor film on the substrate 10 using co-evaporation. The deposition member 130 may include metal vapor sources 131, 132 and 133 below the substrate 10 to provide metal vapor by electron beam. The metal vapor sources may include a source for rare earths, a source for barium, and a source for copper.

18 shows a top view of a reel truing apparatus according to the present invention. 18, the reel turret device 120 includes a first reel member 121 and a second reel member 122, and the first reel member 121 and the second reel member 122 are spaced apart from each other . The deposition member 130 is positioned below the substrate positioned between the first reel member 121 and the second reel member 122. [ The first reel member 121 and the second reel member 122 multiturn the substrate 10 in the region where the superconducting precursor film is deposited. That is, the substrate 10 is rotated between the first reel member 121 and the second reel member 122, and is returned to the first reel member 121 and the second reel member 122. A first reel member 121 is provided adjacent the first side wall 111 of the process chamber 110 and a second reel member 122 is provided adjacent to the second side wall 112 of the process chamber 110 . The first reel member 121 and the second reel member 122 may have the same configuration. The first reel member 121 and the second reel member 122 may extend in a direction intersecting with the reciprocating direction of the substrate 10.

The first reel member 121 and the second reel member 122 include reels arranged and coupled in the extending direction of the first reel member 121 and the second reel member 122, respectively. The substrate 10 turns once at each reel. Each reel can be independently driven and rotated by a frictional force with the substrate 10. The second reel member 122 is disposed slightly shifted from the first reel member 121 for the multi-turn of the substrate 10. As shown in Fig. The substrate 10 moves in the extending direction of the first reel member 121 and the second reel member 122 while moving the first reel member 121 and the second reel member 122.

19 is a cross-sectional view schematically showing a heat treatment unit 200 of an apparatus for forming a superconductor according to the present invention. 19, the thermal processing unit 200 may include a first container 210, a second container 220, and a third container 230, which can sequentially pass through the substrate 10 and, in turn, have. The first container 210 and the third container 230 are spaced from each other. The central portion of the second vessel 220 may correspond to a space in which the first vessel 210 and the third vessel 230 are spaced from each other. The second vessel 220 is configured to surround a portion of each of the first vessel 210 and the third vessel 230. The first container 210, the second container 220, and the third container 230 may be composed of a cylindrical quartz. The first container 210 may be connected to the lead-out portion 114 of the thin film deposition unit 100. The first vessel and the third vessel may include inlet and outlet portions 211, 212, 231, 232 through which the substrate 10 may pass. The substrate 10 is drawn into the first inlet 211 of the first vessel and drawn out to the first outlet 212 of the first vessel and passes through the center portion of the second vessel, Can be drawn into the second inlet portion 231 and drawn out to the second outlet portion 232 of the third container.

The first container 210, the second container 220 and the third container 230 can maintain independent vacuum. To this end, the first vessel 210, the second vessel 220, and the third vessel 230 may have separate pumping ports 214, 224, and 234, respectively, and oxygen feeds (not shown). Oxygen is supplied through the oxygen supplying portions so that the oxygen partial pressures in the first container 210, the second container 220, and the third container 230 can be adjusted independently of each other. For example, the oxygen partial pressure in the first vessel 210 is lower than the oxygen partial pressure in the third vessel 230 and the oxygen partial pressure in the second vessel 220 is higher than the oxygen partial pressure in the first vessel 210, Lt; RTI ID = 0.0 &gt; O2 &lt; / RTI &gt; The oxygen partial pressure in the second vessel 220 can be increased toward the portion adjacent to the third vessel 230 in the portion adjacent to the first vessel 210. [

The first container 210, the second container 220 and the third container 230 are provided in a surrounding furnace. The portion where the first container 210 and the third container 230 are spaced apart may be located near the center of the furnace. Accordingly, the temperature in the vicinity of the center of the second vessel 220 can be maintained higher than the temperature in the first vessel 210 and the third vessel 230. The temperature in the first container 210 and the third container 230 may be lowered away from the center portion of the second container 220. [

The heat treatment process according to the above-described embodiments is described together with the heat treatment unit 200 of Fig. The path IA may be performed while the substrate 10 passes through the first vessel 210 of the thermal processing unit 200. [ The first vessel 210 may have a relatively low oxygen partial pressure (for example, 1 x 10 ^-6 to 1 x 10 ^-3 Torr). The temperature in the first container 210 may be increased from the first inlet 211 to about 800 ° C at the first outlet 212. The path IB can be performed while the substrate 10 passes through the central portion of the second vessel 220 of the heat treatment unit 200. [ The second vessel 220 may have an oxygen partial pressure of, for example, 1 × 10 ^-2 to 10 ^-1 Torr. The oxygen partial pressure in the second vessel 220 can be increased toward the portion adjacent to the third vessel 230 in the portion adjacent to the first vessel 210. [ The temperature of the central portion of the second vessel 220 may be approximately 850 DEG C or higher. The path IC may be performed while the substrate 10 passes through the third vessel 230 of the thermal processing unit 200. [ The third vessel 230 may have an oxygen partial pressure of, for example, 5 × 10 ^-2 to 3 × 10 ^-1 Torr. The temperature in the third container 230 may decrease from approximately 850 ° C of the second inlet 221 to the second outlet 222.

In the above-described example, the thin film deposition unit 100, the heat treatment unit 200, and the substrate supply / recovery unit 300 are integrally formed and the substrate 10 is continuously transported. However, the present invention is not limited thereto.

In one embodiment, the supply / recovery unit 300 may first be provided separately in each of the thin film deposition unit 100 and the heat treatment unit 200. First, a substrate supply / recovery unit with a substrate wound thereon is mounted on the thin film deposition unit 100. In the thin film deposition unit 100, a superconducting precursor is formed on a substrate. The thin film deposition unit 100 may have a different structure from the above-described example. For example, the thin film deposition unit 100 may be for Metal Organic Deposition (MOD). Next, the wire feeding / collecting unit wound around the substrate on which the superconducting precursor is formed is separated from the thin film deposition unit 100. The substrate on which the superconducting precursor is formed may be mounted on the heat treatment unit 200. The substrate on which the superconducting precursor is formed is then heat treated.

In another embodiment, the substrate may not be a wire type but may be a large area plate. In such a case, the supply / recovery unit may have a structure different from the above-described example. The substrate is provided in a thin film deposition apparatus, and a superconducting precursor is formed on the substrate. The substrate on which the superconducting precursor is formed is provided and heat treated in an apparatus capable of performing the above-described heat treatment steps.

Claims (11)

Providing a first superconducting precursor comprising rare earth, barium and copper;
Performing a pre-heat treatment process on the first superconducting precursor to form a first superconductor in which rare-earth-copper-barium oxide is epitaxially grown; And
Performing a post-heat treatment process on the epitaxially grown first superconductor to form a second superconductor,
Wherein the pre-heat treating step comprises:
Heat treating the first superconducting precursor at a first temperature and a first oxygen partial pressure to form an amorphous second superconductor precursor;
Heat treating the amorphous second superconducting precursor at the first temperature and a second oxygen partial pressure higher than the first oxygen partial pressure to form a liquid third superconducting precursor containing rare earth oxide grains; And
Treating the liquid third superconducting precursor with the second oxygen partial pressure and a second temperature lower than the first temperature to form the first superconductor with the epitaxial growth and the copper oxide grains in the first epitaxially grown superconductor &Lt; / RTI &gt;
Wherein the post-heat treatment process comprises annealing the epitaxially grown first superconductor at a third oxygen partial pressure higher than the second oxygen partial pressure and a third temperature lower than the first temperature and higher than the second temperature, And forming copper oxide plates aligned in the c-axis direction in the first superconductor. The method according to claim 1,
Wherein the first superconducting precursor is heat treated at the first oxygen partial pressure of 10 ^-6 to 10 ^-3 Torr and at the first temperature of 860 ° C. The method according to claim 1,
Wherein the amorphous second superconducting precursor is heat treated at the second oxygen partial pressure of 10 ^-2 to 10 ^-1 Torr and at the first temperature of 860 ° C. The method according to claim 1,
Wherein the liquid third superconducting precursor is heat treated at the second oxygen partial pressure of 30 mTorr and at the second temperature of 740 캜 or lower. The method according to claim 1,
Wherein the epitaxially grown first superconductor is annealed at the third oxygen partial pressure of 300 mTorr and at the third temperature of 800 ° C. The method according to claim 1,
Wherein the rare earth-copper-barium oxide of the epitaxially grown first superconductor is formed from the rare earth oxide grains. The method of claim 6,
Wherein the second superconductor comprises the rare earth oxide grains dispersed therein and the copper oxide grains. The method of claim 6,
Wherein the rare earth oxide is RE ₂ O ₃ , the first superconductor has an image of RE _{1 + x} Ba _{2 - x} Cu ₃ O _{7 -δ} and the second superconductor is RE _{1+ y} Ba _{2 - y} Cu ₃ O ₇ has a phase of _-δ, 0 <x <1, and x> y, and 0 <δ <1,
RE is a lanthanide group element including La, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu. The method of claim 7,
Wherein the second superconductor further comprises RE ₂ BaCuO ₅ . The method according to claim 1,
The rare earth-copper-barium oxide is formed on a tape-shaped substrate,
Wherein the substrate comprises an oxide buffer layer formed on a metal substrate having a texture. The method of claim 10,
Wherein the rare earth oxide grains are grown from the oxide buffer layer into the third superconducting precursor in the liquid phase.

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