WO2006025252A1 - 超伝導薄膜、その製造方法、およびそれを用いた超伝導線材、超伝導デバイス - Google Patents
超伝導薄膜、その製造方法、およびそれを用いた超伝導線材、超伝導デバイス Download PDFInfo
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- WO2006025252A1 WO2006025252A1 PCT/JP2005/015423 JP2005015423W WO2006025252A1 WO 2006025252 A1 WO2006025252 A1 WO 2006025252A1 JP 2005015423 W JP2005015423 W JP 2005015423W WO 2006025252 A1 WO2006025252 A1 WO 2006025252A1
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- 239000010409 thin film Substances 0.000 title claims abstract description 72
- 238000000034 method Methods 0.000 title claims description 32
- 238000004519 manufacturing process Methods 0.000 title claims description 6
- 239000000758 substrate Substances 0.000 claims abstract description 93
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims abstract description 40
- 239000007788 liquid Substances 0.000 claims abstract description 20
- 229910052757 nitrogen Inorganic materials 0.000 claims abstract description 20
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 26
- 239000001301 oxygen Substances 0.000 claims description 26
- 229910052760 oxygen Inorganic materials 0.000 claims description 26
- 239000013078 crystal Substances 0.000 claims description 19
- 229910052772 Samarium Inorganic materials 0.000 claims description 15
- 229910052769 Ytterbium Inorganic materials 0.000 claims description 15
- 229910052727 yttrium Inorganic materials 0.000 claims description 15
- 229910052779 Neodymium Inorganic materials 0.000 claims description 14
- 229910052693 Europium Inorganic materials 0.000 claims description 13
- 229910052688 Gadolinium Inorganic materials 0.000 claims description 13
- 238000005229 chemical vapour deposition Methods 0.000 claims description 11
- 229910052746 lanthanum Inorganic materials 0.000 claims description 11
- 239000000126 substance Substances 0.000 claims description 10
- 238000005240 physical vapour deposition Methods 0.000 claims description 9
- 238000007740 vapor deposition Methods 0.000 claims description 5
- 230000007547 defect Effects 0.000 claims description 4
- 230000003647 oxidation Effects 0.000 claims 1
- 238000007254 oxidation reaction Methods 0.000 claims 1
- 230000001747 exhibiting effect Effects 0.000 abstract description 2
- 239000000203 mixture Substances 0.000 description 36
- 238000004549 pulsed laser deposition Methods 0.000 description 21
- 229910052761 rare earth metal Inorganic materials 0.000 description 20
- 150000002910 rare earth metals Chemical class 0.000 description 20
- 239000010408 film Substances 0.000 description 15
- 230000015572 biosynthetic process Effects 0.000 description 12
- 239000002994 raw material Substances 0.000 description 11
- 238000000151 deposition Methods 0.000 description 9
- 230000008021 deposition Effects 0.000 description 9
- 239000000463 material Substances 0.000 description 7
- 239000002887 superconductor Substances 0.000 description 7
- 229910052751 metal Inorganic materials 0.000 description 6
- 239000002184 metal Substances 0.000 description 6
- 238000004458 analytical method Methods 0.000 description 5
- 239000007789 gas Substances 0.000 description 5
- 230000007423 decrease Effects 0.000 description 4
- 230000005540 biological transmission Effects 0.000 description 3
- 239000012159 carrier gas Substances 0.000 description 3
- 239000013067 intermediate product Substances 0.000 description 3
- 230000007704 transition Effects 0.000 description 3
- 239000012808 vapor phase Substances 0.000 description 3
- 229910002367 SrTiO Inorganic materials 0.000 description 2
- 229910009203 Y-Ba-Cu-O Inorganic materials 0.000 description 2
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 2
- 238000001451 molecular beam epitaxy Methods 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 238000004544 sputter deposition Methods 0.000 description 2
- 229910002480 Cu-O Inorganic materials 0.000 description 1
- 241000700560 Molluscum contagiosum virus Species 0.000 description 1
- 229910018487 Ni—Cr Inorganic materials 0.000 description 1
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 150000001450 anions Chemical class 0.000 description 1
- 230000000903 blocking effect Effects 0.000 description 1
- WUKWITHWXAAZEY-UHFFFAOYSA-L calcium difluoride Chemical compound [F-].[F-].[Ca+2] WUKWITHWXAAZEY-UHFFFAOYSA-L 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 239000010436 fluorite Substances 0.000 description 1
- 230000004907 flux Effects 0.000 description 1
- 230000000149 penetrating effect Effects 0.000 description 1
- 239000012071 phase Substances 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 235000002639 sodium chloride Nutrition 0.000 description 1
- 239000011780 sodium chloride Substances 0.000 description 1
- VWQVUPCCIRVNHF-UHFFFAOYSA-N yttrium atom Chemical compound [Y] VWQVUPCCIRVNHF-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N60/00—Superconducting devices
- H10N60/01—Manufacture or treatment
- H10N60/0268—Manufacture or treatment of devices comprising copper oxide
- H10N60/0828—Introducing flux pinning centres
Definitions
- the present invention relates to a superconducting thin film that can be used in the field of superconducting devices such as superconducting wires or superconducting filters (cables, magnets, shields, current limiters, microwave devices, and intermediate products thereof). And a manufacturing method thereof.
- Oxide-based superconductors represented by the Y—Ba—Cu—O system exhibit a critical temperature Tc higher than that of liquid nitrogen. Therefore, superconducting wires and superconducting devices such as superconducting filters have been developed. Is expected to be applied. When such an oxide-based superconductor is applied to a superconducting wire or a superconducting filter, it is necessary to improve the critical current density c. In addition, in order to prevent a decrease in critical current density in a magnetic field, it is necessary to introduce a pinning point of a quantized magnetic flux penetrating into the superconductor into the superconductor.
- Non-Patent Document 1 H. Yamane et al., J. Appl. Phys., 69 (11), 7948-7960 (1991)
- Non-patent document 2 H. Fuke et al, Appl. Phys. Lett., 60 (21), 2686-2688 (1992)
- Non-patent document 3 M. Sano et al., Supercond. Sci. TechnoL, 9, 478 (1996)
- the present invention does not deteriorate the critical current density characteristic even when the oxide-based superconducting thin film is thickened, and the critical current per unit width in a magnetic field.
- the object of the present invention is to provide an oxide superconducting thin film.
- a superconducting thin film according to the first embodiment of the present invention includes a substrate, an oxide layer on the substrate, and an oxide-based superconducting layer on the substrate and the oxide layer.
- the oxide layer is composed of a plurality of island-shaped portions, and is formed of an oxide having a perovskite structure, which does not exhibit superconductivity at liquid nitrogen temperature!
- each of the plurality of island-shaped portions constituting the oxide layer may have a size of 20 nm or more and 200 nm or less, and the plurality of island-shaped portions constituting the oxide layer. May be arranged at intervals of 20 nm or more and 2 OOnm or less.
- the oxide-based superconducting layer has a chemical formula RE Ba Cu O (wherein RE is La ⁇ Nd ⁇ Sm, Eu ⁇ Gd ⁇ Y and l + x 2-x 3 6 + y
- the oxide layer has a chemical formula RE Ba Cu O (wherein RE is La, Nd, Sm, E l + x 2-x 3 6 + y
- the oxide-based superconducting layer may include crystal defects at positions corresponding to the plurality of island portions.
- the superconducting thin film of this embodiment includes a step of preparing a substrate, and an oxide having a bevelskite structure that does not exhibit superconductivity at a liquid nitrogen temperature, and an oxide including a plurality of island-shaped portions.
- a superconducting thin film according to a second embodiment of the present invention includes a substrate, a first oxide-based superconducting layer on the substrate, and an oxide layer on the first oxide-based superconducting layer.
- the first and second oxide-based superconducting layers have the chemical formula RE and are formed of an acid-solid force having a perovskite structure that does not exhibit superconductivity at liquid nitrogen temperature.
- Ba Cu O (wherein RE is La, Nd, Sm, Eu, Gd, Y l + x 2-x 3 6 + y
- the oxide layer has the chemical formula RE Ba Cu O (wherein l + x 2-x 3 6 + y
- RE is selected from the group consisting of La, Nd, Sm, Eu, Gd, Y and Yb and has 0.2 ⁇ x ⁇ 2.0 and 0 ⁇ y ⁇ 2, Desirably, the axis is formed from an oxide that is perpendicular to the surface of the substrate. Further, each of the plurality of island-shaped portions constituting the oxide layer has a dimension of 20 nm or more and 200 nm or less, and the plurality of island-shaped portions constituting the oxide layer is spaced at an interval of 20 nm or more and 200 nm or less. It may be arranged. Alternatively, the second oxide superconducting layer may include crystal defects at positions corresponding to the plurality of islands.
- the superconducting thin film of this embodiment includes a step of preparing a substrate, a step of forming a first oxide superconducting layer on the substrate, and a liquid nitrogen temperature on the first oxide superconducting layer. No superconductivity is exhibited! / A step of forming an oxide layer composed of a plurality of islands from an oxide having a perovskite structure, and the first oxide-based superconducting layer and the oxide layer on the oxide layer. And forming a second oxide superconducting layer, wherein the first and second oxide superconducting layers have an oxygen partial pressure of 13.3 Pa (0.1 lTorr). From the above, in an atmosphere with a substrate temperature of 680 ° C or higher, you may select a group force that includes physical vapor deposition and chemical vapor deposition.
- the present invention provides a superconducting wire and a superconducting device including the superconducting thin film according to any of the first or second embodiments described above.
- FIG. 1 is a schematic cross-sectional view showing a superconducting thin film according to a first embodiment of the present invention.
- FIG. 2 is a schematic cross-sectional view showing a superconducting thin film according to a second embodiment of the present invention.
- FIG. 3 is a diagram showing an AFM observation image of the oxide layer formed in Example 1.
- the superconducting thin film of FIG. 1 has a substrate 10, an oxide layer 20 on the substrate 10, and an oxide-based superconducting layer 30 on the substrate 10 and the oxide layer 20. It is made of an oxide having a perovskite structure composed of a plurality of island-like portions and not exhibiting superconductivity at liquid nitrogen temperature.
- an oxide substrate, a metal substrate, or the like can be used, but is not limited thereto.
- the oxides that can be used for the substrate 10 are SrTiO, LaAlO, etc.
- the metal that can be used for the substrate 10 includes pure Ni or a Ni-based alloy such as Ni—Cr, Ni—W.
- a substrate obtained by coating an oxide intermediate layer on a metal substrate as described above may be used as the substrate 10.
- the oxide constituting the oxide-based intermediate layer the above-described oxide can be used.
- the substrate 10 to be used preferably has a lattice constant close to that of a superconducting oxide crystal that forms the oxide-based superconducting layer 30 formed thereon. By using such a substrate 10, the c-axis orientation of the oxide-based superconducting layer 30 can be facilitated.
- the oxide layer 20 is formed of a non-superconducting oxide having a perovskite structure that does not exhibit superconductivity at a liquid nitrogen temperature (77 K).
- the oxide layer 20 is formed from RE Ba Cu O (where RE is L l + x 2-x 3 6 + y
- the oxide layer 20 functions as a pinning point in the conductive path of the superconducting thin film, it is desirable that it does not have superconductivity. 0. It is desirable to have a composition in the range 2 ⁇ x ⁇ 2.
- the oxide material that constitutes the oxide layer, RE Ba Cu O has a perovskite structure, and the composition of RE and Ba l + x 2-x 3 6 + y
- the critical temperature varies depending on the ratio (see Non-Patent Document 3). It can be seen that the oxide material having a composition where X is 0.2 or more does not exhibit superconducting properties at liquid nitrogen temperature. More preferably, the power to have a thread in the range of 0.2 ⁇ x ⁇ 0.4 and 0.6 ⁇ y ⁇ l.
- the oxide layer 20 is not necessary, but is preferably c-axis oriented (the normal of the substrate surface is parallel to the c-axis of the oxide).
- the oxide layer 20 is composed of a plurality of finely divided island portions.
- Each of the plurality of island-like portions may have an arbitrary bottom shape such as a circle, a polygon, or an indefinite shape.
- each of the plurality of island-shaped portions may have an arbitrary three-dimensional shape such as a cone shape, a hemispherical shape, or a semi-spheroid shape.
- Each of the plurality of island portions has a dimension of 20 nm or more and 200 nm or less.
- each of the plurality of island-shaped portions means the diameter when the bottom surface shape is circular, and when it has other shapes, it is a circle equal to the bottom area. Means the diameter. Further, the plurality of island-shaped portions are arranged with an interval of 20 nm or more and 200 nm or less. By having such a shape and interval, it is possible to introduce an effective functioning pinning point that blocks the conduction path of the superconducting thin film.
- the oxide layer 20 is formed by physical vapor deposition such as pulsed laser deposition (PLD), vapor deposition, sputtering, molecular beam epitaxy (MBE), or chemical vapor deposition ( It can be formed using chemical vapor deposition such as CVD) or metal organic chemical vapor deposition (MOCVD). It is desirable to use the PLD method in which the composition ratio of the target is well reflected in the composition of the superconducting layer.
- PLD pulsed laser deposition
- MBE molecular beam epitaxy
- CVD chemical vapor deposition
- MOCVD metal organic chemical vapor deposition
- the substrate temperature is set to 680 ° C or higher
- the oxygen partial pressure in the deposition chamber is set to 0.1 lTorr (13.3 Pa) or higher
- the desired composition RE B l + xa Cu O (formula Medium, RE is selected from the group consisting of La, Nd, Sm, Eu, Gd, Y and Yb
- a discontinuous island force is also formed on the substrate 10.
- An oxide layer can be formed. More preferably, the substrate temperature is set to 750 to 850 ° C., and the oxygen partial pressure is set to 0.2 to 0.8 Torr (26.7 to 107 Pa). [0017] Alternatively, when the CVD or MOCVD method is used, the ratio of the source gas of each metal element is set to a desired ratio, the substrate temperature is set to 680 ° C or higher, and the oxygen content in the film formation chamber is set. By setting the pressure to 0.1 lTorr (13.3 Pa) or higher, the oxide layer 20 can be obtained.
- the ratio of the raw material gas can be set appropriately by adjusting the holding temperature of each raw material or the carrier gas flow rate ratio of each raw material. More preferably, the substrate temperature is set to 750 to 850 ° C., and the oxygen partial pressure is set to 0.2 to 0.8 Torr (26.7 to 107 Pa).
- the oxide-based superconducting layer 30 includes RE Ba Cu O containing rare earth (RE) (where RE is l + x 2-x 3 6 + y
- It is selected from a group force consisting of La, Nd, Sm, Eu, Gd, Y and Yb forces, and is formed from a superconducting oxide having a composition of 0.2 ⁇ x ⁇ 2, 0 ⁇ y ⁇ 2). More preferably, it is desirable to have a composition in the range of 0.2 ⁇ x ⁇ 0.4 and 0.6 ⁇ y ⁇ l.2.
- the superconducting oxide forming the oxide-based superconducting layer 30 is deposited in a c-axis orientation (the normal of the substrate surface is parallel to the c-axis of the superconducting oxide), and the substrate surface A superconducting surface (ab surface) parallel to is formed.
- the oxide superconducting layer 30 has a film thickness in the range of usually 0.1 ⁇ m to 5 ⁇ m, preferably 0.1 ⁇ m to 3 ⁇ m.
- the oxide-based superconducting layer 30 can be formed using a vapor phase method, for example, a physical vapor deposition method such as PLD method, vapor deposition method, sputtering method, MBE method, CVD method or MOCV D It can be formed using a chemical vapor deposition method such as a method.
- a particularly preferable method is the PLD method in which the composition ratio of the target is well reflected in the composition of the superconducting layer to be formed.
- the desired composition RE Ba Cu O (where RE is La
- the substrate temperature is set to 750 to 850 ° C.
- the oxygen partial pressure is set to 0.2 to 0.8 Torr (26.7 to 107 Pa).
- a superconducting layer 30 can be obtained.
- the ratio of the raw material gas can be set appropriately by adjusting the flow control valve or the holding temperature of each source. More preferably, the substrate temperature is set to 750 to 850 ° C. and the oxygen partial pressure is set to 0.2 to 0.8 Torr (26.7 to 107 Pa).
- the oxide layer 20 functions as a pinning point in the conductive path of the superconducting thin film, and can prevent the critical current density c in the magnetic field from being lowered.
- stacking faults dislocations, grain boundaries, amorphous bodies, non-superconductors, and low critical temperature
- the stacking fault also functions as an effective pinning point.
- the oxide layer 20 is also formed with a plurality of finely divided island forces, a large current per unit width without interrupting the conductive path in the oxide-based superconducting layer 30 can be obtained. It is possible to flow.
- FIG. 2 shows a superconducting thin film according to the second embodiment of the present invention.
- the superconducting thin film in FIG. 2 includes a substrate 10, a first oxide superconducting layer 40 on the substrate 10, an oxide layer 50 on the first oxide superconducting layer 40, and a first oxide.
- the substrate 10 can be the same as that of the first embodiment.
- a first oxide superconducting layer 40 is formed on the substrate 10.
- the material used for the first oxide-based superconducting layer 40 is the same as that of the oxide-based superconducting layer 30 in the first embodiment, and includes RE Ba Cu O containing rare earth (RE) (where RE Is La
- the first oxide-based superconducting layer 40 is the same as the oxide-based superconducting layer 30 in the first embodiment, such as a physical vapor deposition method such as PLD or a chemical vapor phase such as CVD or MO CVD. It can be performed using a vapor deposition method.
- the substrate temperature is 680 ° C or higher
- the oxygen partial pressure is 0.1 lTorr (13.3 Pa) or higher, more preferably 750 to 850 ° C, and 0.2 to 0.8 Torr.
- the first oxide-based superconducting layer 40 in this embodiment is usually 0.:n! Have a film thickness in the range of ⁇ 5 m, preferably 0.1 ⁇ m to 3 ⁇ m.
- the oxide layer 50 is made of a non-superconducting oxide having a perovskite structure that has superconductivity at a liquid nitrogen temperature (77 K).
- the material used to form the oxide layer 50 is similar to the oxide layer 20 in the first embodiment, as in RE Ba Cu O (where R l + x 2-x 3 6 + y
- E is selected from the group forces consisting of La, Nd, Sm, Eu, Gd, Y and Yb forces, and is formed from 0.2 ⁇ x ⁇ 2, 0 ⁇ y ⁇ 2). Note that the oxide material constituting the oxide layer RE Ba Cu O
- the oxide material having a composition where X is 0.2 or more does not exhibit superconducting properties at liquid nitrogen temperature.
- the oxide layer 50 is not necessary, it is preferable that the c-axis orientation (the normal of the substrate surface and the c-axis of the oxide layer be parallel) is.
- the oxide layer 50 is composed of a plurality of finely divided island portions.
- Each of the plurality of island-like portions may have an arbitrary bottom shape such as a circle, a polygon, or an indefinite shape.
- each of the plurality of island-shaped portions may have an arbitrary three-dimensional shape such as a cone shape, a hemispherical shape, or a semi-spheroid shape.
- Each of the plurality of island portions has a dimension of 20 nm or more and 200 nm or less.
- the plurality of island-shaped portions are arranged with an interval of 20 ⁇ m or more and 200 nm or less.
- the oxide layer 50 is formed using a physical vapor deposition method such as PLD or a chemical vapor deposition method such as CVD or MOCVD, as with the oxide layer 20 of the first embodiment. It can be carried out .
- the substrate temperature is set to 680 ° C or higher
- the oxygen partial pressure in the film formation chamber is set to 0.1 lTorr (13.3 Pa) or higher
- a target having a desired composition or a raw material having a desired flow rate ratio is formed.
- the oxide layer 50 composed of discontinuous island portions can be formed. More preferably, the substrate temperature is set to 750 to 850 ° C., and the oxygen partial pressure is set to 0.2 to 0.8 Torr (26.7 to 107 Pa).
- the second oxide superconducting layer 60 is formed on the first oxide superconducting layer 40 and the oxide layer 50.
- the material used for the second oxide superconducting layer 60 is the same as that of the first embodiment. This is the same as the oxide-based superconducting layer 30 and contains RE Ba Cu O containing rare earth (RE) (in the formula l + x 2-x 3 6 + y, where RE is La, Nd, Sm, Eu, Gd , Y and Yb forces are selected from the group force, and 0 ⁇ x ⁇ 0.2 and 0 ⁇ y ⁇ 2.
- RE rare earth
- the formation of the second oxide-based superconducting layer 60 is the same as the oxide-based superconducting layer 30 in the first embodiment, such as a physical vapor deposition method such as PLD or a chemical vapor phase such as CVD or MOCVD. This can be done by vapor deposition.
- the substrate temperature is 680 ° C or higher
- the oxygen partial pressure is 0.1 lTorr (13.3 Pa) or higher, more preferably 750 to 850 ° C, and 0.2 to 0.8 Torr ( 26. It is desirable to use an oxygen partial pressure of 7 to 107 Pa).
- the second oxide superconducting layer 60 in the present embodiment has a film thickness in the range of usually 0.1 ⁇ m to 5 ⁇ m, preferably 0.1 ⁇ m to 3 ⁇ m.
- the oxide layer 50 exists between the first oxide superconducting layer 40 and the second oxide superconducting layer 60, that is, inside the conductive path, and the superconducting thin film It functions as a pinning point in the conduction path and can prevent a decrease in the critical current density c in the magnetic field.
- the second oxide superconducting layer 60 formed above the oxide layer 20 there are stacking faults (dislocations, grain boundaries, amorphous bodies, non-superconductors and low criticality). It is considered that the stacking fault also functions as an effective pinning point.
- the oxide layer 50 is formed from a plurality of finely divided island-shaped portions, the conductive paths in the first oxide-based superconductive layer 40 and the second oxide-based superconductive layer 60 It is possible to pass a large current per unit width that cannot be interrupted.
- a substrate 10 made of MgO was placed in a pulsed laser deposition (PLD) apparatus, the substrate temperature was set to 830 ° C., and the oxygen partial pressure in the deposition chamber was set to 0.4 Torr (53.3 Pa).
- PLD pulsed laser deposition
- the get was irradiated with an excimer laser to form oxide layers 20 having various compositions.
- the c-axis of the crystal is perpendicular to the surface of the substrate 10 in any of the oxide layers 20 of any composition (ie, c-axis orientation) Confirmed).
- Fig. 3 Such a surface observation image was obtained. From the observation images of the respective samples, the oxide layer 20 of any composition is composed of a plurality of island-shaped portions, the plurality of island-shaped portions have a size of 20 to 200 nm, and the island-shaped portions are It was confirmed that they are arranged at intervals of about 20 to 200 nm.
- the substrate 10 on which the oxide layer 20 is formed is placed again in the PLD apparatus, the substrate temperature is set to 830 ° C., and the oxygen partial pressure in the deposition chamber is set to 0.4 Torr (53.3 Pa). Set. Sm Ba l + x 2-x
- the target was irradiated with an excimer laser to form a 2 m thick oxide-based superconducting layer 30 having various compositions.
- the c-axis of the crystal is perpendicular to the MgO substrate surface (ie, C-axis orientation).
- the SmZBa ratios in the oxide layer 20 were 0.2, 0.3, and 0.4, respectively. It was confirmed that the SmZBa ratios in the conductive layer 30 were 0, 0.04, and 0.08, respectively (in this example, the SmZBa ratio is represented by x in the composition formula SmBaCuO). L + x 2-x 3 6 + y
- the oxide layer 20 obtained by the PLD method and the oxide-based superconducting layer 30 had a perovskite structure having the same composition as the target using the force and c-axis oriented. confirmed. Furthermore, since the SmZBa ratio in the oxide layer 20 is 0.2 or more, it is estimated that the oxide layer 20 does not exhibit superconductivity at the liquid nitrogen temperature.
- the superconducting transition temperature Tc of the obtained superconducting thin film and the critical current density c when no magnetic field was applied at a liquid nitrogen temperature (77 K) were measured. Furthermore, Jc at a temperature of 77 K was measured when a magnetic field (5T and 9T) was applied in the direction parallel to the c-axis of the oxide-based superconducting layer 30 (that is, perpendicular to the surface of the substrate 10).
- the superconducting thin film of V and shear also had a Tc of 90K or more.
- Jc without magnetic field at 77K was 2 X 10 6 AZcm 2 or more for any superconducting thin film.
- the highest value of Jc 7.9 X 10 6 AZcm 2 is obtained. Obtained It was.
- the superconducting thin film can obtain Jc of 3 X 10 5 AZcm 2 at 5 T (Tesla) and 1 X 10 5 AZcm 2 at 9 T even when a magnetic field parallel to the c-axis is applied (temperature 77 K). It was confirmed.
- the substrate with MgO force was placed in a pulsed laser deposition (PLD) apparatus, the substrate temperature was set to 830 ° C, and the oxygen partial pressure in the deposition chamber was set to 0.4 Torr (53.3 Pa).
- PLD pulsed laser deposition
- the exciter laser was irradiated to the substrate to form oxide superconducting layers (thickness 1 ⁇ m) having various compositions.
- the c-axis of the crystal is perpendicular to the MgO substrate surface in any of the oxide-based superconducting layers of any composition (that is, c-axis orientation).
- Jc was measured when a magnetic field parallel to the c-axis was applied at a temperature of 77K.
- Jc decreased to 4 X 10 4 AZcm 2 .
- Jc was 10 3 AZcm 2 or less.
- the decrease in Jc at the time of application of the magnetic field is due to the fact that the peaking point due to the oxide layer 20 was not introduced.
- a substrate 10 made of MgO was placed in a pulsed laser deposition (PLD) apparatus, the substrate temperature was set to 830 ° C., and the oxygen partial pressure in the deposition chamber was set to 0.4 Torr (53.3 Pa).
- PLD pulsed laser deposition
- the target was irradiated with an excimer laser to form a first oxide superconducting layer 40 (film thickness 0.3 m) having various compositions.
- the obtained first oxide superconducting layer 40 was analyzed. As a result, it was confirmed that the first oxide-based superconducting layer 40 of any composition has a perovskite structure with c-axis orientation.
- the substrate 10 on which the first oxide superconducting layer 40 is formed is again placed in the PLD apparatus, the substrate temperature is set to 830 ° C., and the oxygen partial pressure in the film forming chamber is set to 0. It was set to 4 Torr (53.3 Pa).
- Gd Ba Cu O (x 0.1, 0.2, 0.3, 0.4; 0.6 ⁇ y ⁇ 1.2) target quasi l + x 2-x 3 6 + y
- each target was irradiated with an excimer laser to form an oxide layer 50 having various compositions.
- the oxide layer 50 having any composition also has a c-axis oriented perovskite structure.
- the oxide layer 50 has a size of 20 to 200 nm and a plurality of layers arranged at intervals of about 20 to 200 nm. It was confirmed that it was composed of islands!
- the substrate 10 on which the first oxide-based superconducting layer 40 and the oxide layer 50 are formed is placed again in the PLD apparatus, the substrate temperature is set to 780 ° C, and the oxygen partial pressure in the film formation chamber is It was set to 0.4 Torr (53.3 Pa).
- Gd Ba Cu O (x 0, 0.0.04, 0. 08; 0.6 ⁇ y ⁇ l. 2) l + x 2-x 3 6 + y
- Each target was irradiated with an excimer laser to form second oxide-based superconducting layers 60 (film thickness 0.8 m) having various compositions.
- second oxide superconducting layer 60 As a result of analyzing the obtained second oxide superconducting layer 60, it was confirmed that the second oxide superconducting layer 60 of any composition has a perovskite structure with c-axis orientation.
- the GdZBa ratios in the oxide layer 50 are 0.1, 0.2, 0.3, and 0.4, respectively. It was confirmed that the GdZBa ratios in the dioxide superconducting layer 60 were 0, 0.04, and 0.08, respectively (in this example, the GdZBa ratio is l + x 2 in the composition formula GdBaCuO). -x 3 6 + y
- the oxide layer 50 does not exhibit superconductivity at the liquid nitrogen temperature.
- the superconducting transition temperature Tc of the obtained superconducting thin film and the critical current density c when no magnetic field was applied at a liquid nitrogen temperature (77 K) were measured. Furthermore, Jc at a temperature of 77 K was measured when a magnetic field (5T and 9T) was applied in the direction parallel to the c-axis of the oxide-based superconducting layer 30 (that is, perpendicular to the surface of the substrate 10). As a result, the superconducting thin film of V and shear also had Tc of 90K or more. In addition, Jc at a temperature of 77K with no magnetic field applied was 1 X 10 6 AZcm 2 or higher for any superconducting thin film.
- the highest Jc 5.0 X 10 6 A / A value of cm 2 was obtained. Furthermore, superconducting thin film, even when the application of a magnetic field parallel to the c-axis (temperature 77K), at 5T (Tesla) 2. 3 X 10 5 A / cm 2, 9T in 0. 5 X 10 5 A / It was confirmed that cm 2 of Jc was obtained.
- a substrate 10 made of SrTiO is placed in a metal organic chemical vapor deposition (MOCVD) apparatus, and the substrate
- Nd (DPM), Ba (DPM), Cu (DPM) (where DPM is dipivalol methane) with the temperature set to 830 ° C and the oxygen partial pressure in the deposition chamber set to 3 Torr (400 Pa) Represents an anion
- An oxide layer 20 was formed as a raw material. Nd (DPM) raw material holding temperature of 125 ° C,
- Holding temperature of Ba (DPM) raw material is 240 ° C, and holding temperature of Cu (DPM) raw material is 120
- the film was formed at 10 ° C. for 10 seconds.
- the oxide layer 20 has a size of 20 to 200 nm and a plurality of islands arranged at intervals of about 20 to 200 nm. It was confirmed that the striated part force was also constructed.
- an oxide layer 20 having a composition with an NdZBa ratio of 0.4 was formed by controlling the carrier gas flow rate of the raw material (in this example, the NdZBa ratio is represented by the composition formula Nd Ba
- the substrate 10 on which the oxide layer 20 is formed is placed again in the PLD apparatus, the substrate temperature is set to 830 ° C, and the oxygen partial pressure in the deposition chamber is set to 0.4 Torr (53.3 Pa).
- Nd Ba Cu O (x 0.04; 0.6 ⁇ yl + x 2-x 3 6) by MOCVD method with changed carrier gas flow rate of raw material
- the NdZBa ratio in the oxide layer 20 is 0.4
- the NdZ in the oxide superconducting layer 30 is It was confirmed that the Ba ratio was 0.04 respectively.
- the obtained superconducting thin film also had a Tc of 90K or more.
- Jc without a magnetic field was greater than or equal to l X 10 6 AZcm 2 at a temperature of 77K.
- Jc of 1.4 X 10 5 AZcm 2 was obtained at 5T (Tesla) even when a magnetic field parallel to the c-axis was applied (temperature 77K).
- the superconducting thin film of the present invention exhibited a critical temperature Tc equivalent to that of the conventional superconducting thin film, and had a critical current density equal to or higher than that of the conventional film in the absence of a magnetic field. Furthermore, the superconducting thin film of the present invention exhibited a significantly higher critical current density than the conventional superconducting thin film under application of a magnetic field. Therefore, the superconducting thin film of the present invention can pass a larger amount of current when operating under the influence of a magnetic field, and is not limited to a device that should operate in such an environment. It is suitable for use in conductive wires and superconducting devices such as cables, magnets, shields, current limiters, microwave devices, superconducting filters, and intermediate products used for their production.
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JP2003008090A (ja) * | 2001-06-19 | 2003-01-10 | National Institute Of Advanced Industrial & Technology | ナノドットを利用した柱状ピン止め中心を有する超伝導薄膜及びその製造方法 |
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JP2003008090A (ja) * | 2001-06-19 | 2003-01-10 | National Institute Of Advanced Industrial & Technology | ナノドットを利用した柱状ピン止め中心を有する超伝導薄膜及びその製造方法 |
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