Flexible high-temperature superconductor and method for its production
20230034446 · 2023-02-02
Inventors
- Sergei R. LI (Moscow, RU)
- Anton V. MARKELOV (Moscow, RU)
- Alexandre A. MOLODYK (Moscow, RU)
- Valerii V. PETRYKIN (Moscow, RU)
- Sergei V. SAMOILENKOV (Moscow, RU)
Cpc classification
Y02E30/10
GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
International classification
Abstract
The invention relates to electrical engineering, in particular, to the manufacturing technology of flexible high-temperature superconductors (HTS) with high critical current density in external magnetic field and to the method of manufacturing of said superconductors (tapes). The invention is applicable to industrial manufacturing of HTS wires with very high values of critical current density in magnetic fields over 1 Tesla at temperatures below 50 Kelvin, in particular, to industrial manufacturing of HTS wires intended for application in compact fusion reactors. Flexible high temperature superconductor is comprised of a substrate and a superconductor layer with RE.sub.1+2xBa.sub.2Cu.sub.3O.sub.7+3x overall composition comprised of a superconductor matrix of REBa.sub.2Cu.sub.3O.sub.7 composition and non-superconducting nanoparticles of RE.sub.2O.sub.3 composition, where x=0.05-0.15, RE is a rare earth element from the Y, Dy, Ho, Er, Tm, Yb and Lu group, whereas the concentration density of the said nanoparticles is at least 10.sup.16 nanoparticles/cm.sup.3. Method of manufacturing of the superconductor is comprised of pulsed laser deposition of superconductor material with RE.sub.1+2xBa.sub.2Cu.sub.3O.sub.7+3x overall composition, where x=0.05-0.15, RE is rare earth element from the Y, Dy, Ho, Er, Tm, Yb and Lu group, onto a substrate moving through the deposition zone and heated to a temperature of at least 800° C., whereas the deposition is performed using an ablated target made from multiphase sintered ceramics comprised of chemical elements that compose the superconductor material, at a deposition rate greater than 100 nm/s and at a temperature gradient in the deposition zone that ensures the deposition of the superconductor material without the formation of liquid phase. The invention allows for improvement of the properties of flexible high temperature superconductor by increasing its critical current in high magnetic fields and ensures simple and economic large scale production of said HTS conductor with improved properties.
Claims
1. A flexible high temperature superconductor comprising: a substrate and a superconductor layer having an RE.sub.1+2xBa.sub.2Cu.sub.3O.sub.7+3x overall composition; the superconductor layer comprising a superconductor matrix having an REBa.sub.2Cu.sub.3O.sub.7 composition and non-superconducting nanoparticles of an RE.sub.2O.sub.3 composition; the nanoparticles having a concentration density of at least 10.sup.16 nanoparticles/cm.sup.3, wherein: x=0.05-0.15, RE is a rare earth element selected from the group consisting of Y, Dy, Ho, Er, Tm, Yb and Lu.
2. The superconductor of claim 1, wherein a thickness of the superconductor is from 1.5 to 3.5 microns.
3. The superconductor of claim 1, wherein the concentration density of the non-superconducting nanoparticles is from 10.sup.16 to 10.sup.18 nanoparticles/cm.sup.3.
4. The superconductor of claim 1, wherein the non-superconducting RE.sub.2O.sub.3 nanoparticles are essentially of an isotropic shape and of a size no larger than 10 nm and they are uniformly distributed within an entire volume of the superconductor matrix.
5. The superconductor of claim 4, wherein said non-superconducting nanoparticles have (110) RE.sub.2O.sub.3 axial texture with the following epitaxial relations with the superconductor matrix: [001](110)RE.sub.2O.sub.3//[010](001)REBa.sub.2Cu.sub.3O.sub.7.
6. The superconductor of claim 1, wherein a size of RE.sub.2O.sub.3 nanoparticles in a plane parallel to a (001) REBa.sub.2Cu.sub.3O.sub.7 crystallographic plane is no larger than 30 nm and no larger than 5 nm in a direction perpendicular to the (001) REBa.sub.2Cu.sub.3O.sub.7 crystallographic plane.
7. The superconductor of claim 6, wherein non-superconducting RE.sub.2O.sub.3 nanoparticles with the size larger than 10 nm in the plane parallel to the (001) REBa.sub.2Cu.sub.3O.sub.7 crystallographic plane are distributed in the superconductor matrix as layers assembled parallel to said crystallographic plane.
8. The superconductor of claim 7, wherein a distance between said layers of non-superconducting RE.sub.2O.sub.3 nanoparticles is from 20 to 100 nm.
9. The superconductor of claim 7, wherein non-superconducting nanoparticles have (001) RE.sub.2O.sub.3 axial texture with the following epitaxial relations with the superconductor matrix: [100](001) RE.sub.2O.sub.3//[110](001) REBa.sub.2Cu.sub.3O.sub.7.
10. The superconductor of claim 1, wherein RE is yttrium.
11. The superconductor of claim 1 being a tape comprised of a substrate, at least one buffer layer and a superconductor layer, the superconductor being characterized by typical lift-factor values for such orientation of an external magnetic field that the orientation corresponds to a minimum value of critical current at a 20 T magnetic field strength, the minimum value being 2.55±0.27 at 4.2 K and 1.13±0.17 at 20 K.
12. The superconductor of claim 1 being a tape comprised of a substrate, at least one buffer layer and a superconductor layer, and for the superconductor are typical the following absolute values of critical current: at least 400 A/cm at 20 K and at least 875 A/cm at 4.2 K at a magnetic field strength of 20 T.
13. A method of manufacturing of flexible high temperature superconductor, the method comprising: pulsed laser depositing of a superconductor material onto a substrate moving through a deposition zone and heated to a temperature of at least 800° C.; and performing pulsed laser depositing using an ablated target made from multiphase sintered ceramics comprised of chemical elements that compose the superconductor material, at a deposition rate greater than 100 nm/s and at a temperature gradient in the deposition zone that ensures depositing of the superconductor material without forming a liquid phase; wherein RE.sub.1+2xBa.sub.2Cu.sub.3O.sub.7+3x is an overall composition of the superconductor material, x=0.05-0.15, and RE is a rare earth element selected from the group consisting of Y, Dy, Ho, Er, Tm, Yb and Lu.
14. The method of claim 13, wherein pulsed laser depositing is performed at a pulse repletion rate of up to 300 Hz and a pulse energy of from 500 to 1000 mJ.
15. The method of claim 13, wherein pulsed laser depositing is performed at a temperature gradient in the deposition zone of from 50 to 300° C./cm.
Description
BRIEF DESCRIPTION OF THE DRAWING FIGURES
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DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0055] The essence of the invention is as follows.
[0056] Claimed flexible high-temperature superconductor is the second-generation flexible high-temperature superconductor. Such superconductors are comprised of a metal substrate and a superconductor layer. Typically, between the substrate and the superconductor layer, there are located buffer layers, which, as was mentioned above, translate the biaxial texture to the superconductor layer. The biaxial texture can be formed either in the metal substrate or in one of the buffer layers.
[0057] The overall composition of the superconductor layer in present invention is RE.sub.1+2xBa.sub.2Cu.sub.3O.sub.7+3x, where x=0.05-0.15, and the structure of the superconductor layer is comprised of the superconductor matrix of REBa.sub.2Cu.sub.3O.sub.7 composition and non-superconducting RE.sub.2O.sub.3 nanoparticles. According to the invention, RE is a rare earth element from the Y, Dy, Ho, Er, Tm, Yb and Lu group. The choice of the RE elements is based on the values of their effective ionic radii r(R.sup.3+, CN 8) of from 0.0870 to 0.1027 nm, where r is the effective ionic radius, R.sup.3+ is the oxidation state of +3, CN 8 is the coordination number of 8. In other words, these elements have reasonably small ionic radii and, in contrast to such rare earth element as, for example, Gd, Eu and Sm cannot substitute barium in the superconductor structure, forming the RE.sub.1+xBa.sub.2−xCu.sub.3O.sub.7 solid solution.
[0058] Because of that, REBa.sub.2Cu.sub.3O.sub.7 with the selected RE are “point” compounds on the phase diagram, that is they have very narrow cation homogeneity regions, and thus, when the conditions allow diffusion, excessive RE atoms cannot incorporate into the REBCO structure.
[0059] In this case, in the superconductor layer with RE.sub.1+xBa.sub.2−xCu.sub.3O.sub.7+3x overall composition, rare earth oxide is crystallized and thus it ensures the required structure of the superconductor matrix with non-superconducting RE.sub.2O.sub.3 nano-inclusions having the claimed density of such particles.
[0060] The low crystallographic lattice mismatch between RE.sub.2O.sub.3 and REBa.sub.2Cu.sub.3O.sub.7 (for example, for RE=Y the lattice mismatch is <3%) prevents significant mechanical strain in the superconductor layer and, therefore, is beneficial for the superconducting properties of the claimed superconductor and constitutes an essential difference of our method from the methods where the HTS layer contains nano-columns and where the superconductor crystallographic c-parameter increases with increasing content of the columnar nano-inclusions (see U.S. Pat. No. 8,034,745).
[0061] The concentration density of non-superconducting RE.sub.2O.sub.3 nanoparticles is at least 10.sup.16 nanoparticles/cm.sup.3. Such a high nanoparticle concentration density is an extremely important feature that enables high values of critical current density, because RE.sub.2O.sub.3 nanoparticles and associated structural defects surrounding them such as dislocations, point defects, antiphase boundaries and others, act a pinning centers that hold the magnetic field vortices. The upper boundary of the claimed nanoparticle concentration density is limited by thermodynamic and kinetic factors, in particular, by the diffusion mobility of the components of the growing film. We have obtained good results for the nanoparticle density of 10.sup.18 nanoparticles/cm.sup.3.
[0062] In the art, a nanoparticle is an isolated solid phase object that has a well-defined boundary with surrounding medium, and the size of that object in each of the three dimensions is from 1 to 100 nm.
[0063] In the present invention, RE.sub.2O.sub.3 non-superconducting particles meet this definition, including the size range. In the best embodiments, RE.sub.2O.sub.3 nanoparticle size in the plane parallel to the (001) REBa.sub.2Cu.sub.3O.sub.7 crystallographic plane is no greater than 30 nm, and in the direction perpendicular to the (001) REBa.sub.2Cu.sub.3O.sub.7 crystallographic plane is no greater than 5 nm. The shape of the non-superconducting particles can be isotropic and non-isotropic, that is the particles can be of an approximately cubic shape or they can also be elongated in the plane parallel to the (001) REBa.sub.2Cu.sub.3O.sub.7 crystallographic plane.
[0064] RE.sub.2O.sub.3 nanoparticles can be uniformly distributed in the REBa.sub.2Cu.sub.3O.sub.7 matrix, or, in addition to that, they can assemble in the matrix into layers parallel to the (001) REBa.sub.2Cu.sub.3O.sub.7 crystallographic plane. The first arrangement (uniform distribution) is more typical when the nanoparticle size, at the claimed concentration density, is no greater than 10 nm in the plane parallel to the (001) REBa.sub.2Cu.sub.3O.sub.7 crystallographic plane, whereas the second arrangement (in layers) is more typical when the nanoparticle size, at the claimed concentration density, is greater than 10 nm in the plane parallel to the (001) REBa.sub.2Cu.sub.3O.sub.7 crystallographic plane. In the first arrangement (uniform distribution) the non-superconducting nanoparticles have (110) RE.sub.2O.sub.3 axial texture, and in the second arrangement (in layers) the non-superconducting nanoparticles have (001) RE.sub.2O.sub.3 axial texture. It should be noted that the superconductor in which RE.sub.2O.sub.3 nanoparticles are assembled in layers in the REBa.sub.2Cu.sub.3O.sub.7 matrix has no clear advantages in the performance in magnetic field comparing to the superconductor without such assembly.
[0065] Above we presented our analysis of the requirements to rare earth elements suitable for this method and of the particular group of elements that meet the requirements. Yttrium stands out among the elements in this group. It has the lowest atomic weight and hence the highest diffusion coefficient in the group. This results in a faster formation of non-superconducting nanoparticles. In addition, the yttrium price is reasonable because of its good natural availability, and there are other advantages to yttrium such as the very low neutron cross-section, which is an added advantage to the use of yttrium-based HTS wires in fusion reactors.
[0066] Essential for our invention is also the thickness of the superconductor layer. Naturally, with a thicker superconductor layer and a thinner substrate, enhanced performance of the second-generation HTS wire can be attained, in particular, a higher engineering current density; however, it is difficult to manufacture such superconductors economically and with a high production yield.
[0067] We industrially manufacture, using pulsed laser deposition, flexible superconductors with the thickness of the superconductor layer of at least 1.5 microns and even up to 3.5 microns, on the average of 2.4±0.3 microns.
[0068] The method to manufacture claimed flexible superconductor includes pulsed laser deposition of the superconductor material with RE.sub.1+2xBa.sub.2Cu.sub.3O.sub.7+3x overall composition onto a moving substrate heated to a temperature of at least 800° C. The deposition is performed using an ablated target made of a multiphase sintered ceramics of the elements that compose the superconductor material. The deposition rate is greater than 100 nm/second and a temperature gradient in the deposition zone between the substrate and other equipment parts is such that it will ensure the deposition of the superconductor material without the formation of liquid phase.
[0069] The substrate temperature is set at a relatively high value (at least 800° C.) so that it will promote high diffusion mobility of the components of the film being grown on the substrate. The maximum temperature is limited by the thermodynamic stability of REBa.sub.2Cu.sub.3O.sub.7.
[0070] The film growth is performed at a temperature gradient that differentiates our method from known methods (hot wall PLD) in which the tape is kept at temperature equilibrium (is surrounded by hot environment). Our requirement to the temperature gradient is such that no liquid phase is formed when the superconductor material is deposited. This ensures that the deposition conditions (oxygen partial pressure and temperature) at the substrate surface are within the superconductor (REBa.sub.2Cu.sub.3O.sub.7-y) thermodynamic stability range, while the diffusion rate of the deposited material species favors the formation of non-superconducting particle inclusions. The presence of liquid phase would result in large crystallites thus impeding or preventing the formation of the required micro- and nano-structure in the superconductor layer.
[0071] The film is grown in a pulsed mode at a very high local deposition rate (over 100 nm/s). The maximum of the deposition rate range is limited by the diffusion mobility of the film growth medium; however, at the state of the art, the achievable maximum deposition rate is limited by the technical specifications of pulsed laser deposition equipment. The high film growth rate is possible due to the absence of diffusion-limiting factors such as, for example, counter-diffusion of oxidized components of metal-organic compounds from the film growth region or high CO.sub.2 concentration that are typical for chemical vapor deposition (WO2020117369 A). Indeed, in MOCVD the film growth rate is constant and insignificant, being 5-20 nm/s, which is many times lower than in our method.
[0072] For HTS layer deposition, only the HTS components are used: RE, barium and copper. The composition and concentration of defects, the dominant defects being RE.sub.2O.sub.3 nanoparticles, are mainly controlled by the composition of the PLD target.
[0073] The PLD target is a sintered multi-phase ceramics containing the RE.sub.2BaCuO.sub.5, CuO and REBa.sub.2Cu.sub.3O.sub.7-y phases. The cation ratio is determined by the following: the amount of RE oxide inclusions is a function of the [RE]/[Ba] ratio in the target, and the amount of copper in the target is selected so that the resulting film will not contain copper oxide inclusions, according to the data of x-ray diffraction and electron microscopy.
[0074] All of the above ensures the fabrication of high temperature superconductor with unique high superconducting performance in magnetic field.
[0075] Pulsed laser deposition can be performed under various conditions, depending on the equipment used. In particular, in our embodiments under industrial manufacturing conditions, it is appropriate to perform pulsed laser deposition at a pulse repetition rate of up to 300 Hz and a pulse energy of 500-1000 mJ. Not only do such parameters ensure the claimed technical result, but also they allow for the most productive industrial operation. All of the above does not mean that it is impossible to perform pulsed laser deposition at other pulse repetition rates and/or other pulse energy values.
[0076] As stated above, one of the technical requirements is to create a temperature gradient in the deposition zone, so that no liquid phase will form during the superconductor material deposition.
[0077] The required gradient is created by heating the substrate onto which the superconductor layer is being deposited. The deposition chamber walls are either heated insignificantly due to the heat transfer from the substrate or remain cold. The calculation of the temperature gradient that prevents the formation of liquid phase is performed using the pulsed laser deposition equipment parameters (see below). In our equipment, pulsed laser deposition is performed at a temperature gradient of 50-300° C./cm.
Examples of the Embodiments of Invention
[0078] The following embodiment example makes it easier to understand the pulsed laser deposition process.
[0079] Superconductor was fabricated on a strong substrate tape made of Hastelloy C276. The substrate thickness was 40 microns and the substrate width was 12 mm After the deposition of the HTS layer and the protective silver layer the tape was slit from 12 mm width to three strips of 4 mm width each; after that, a protective copper layer of the overall thickness of 10 microns (5 microns per side) was electroplated onto the strips. Prior to the HTS layer deposition, buffer layer architecture based on IBAD-MgO with the LaMnO.sub.3 top layer was deposited onto the substrate. The HTS layer was grown by pulsed laser deposition.
[0080] According to the schematic in
[0081] HTS layer deposition was performed by the condensation of the constituent elements, yttrium, barium, copper and oxygen, from plasma plume 3 formed during ablation of ceramic target 4 with focused laser beam 2 of an excimer laser with a wavelength of 308 nm. Coherent LEAP 130C (200 Hz) and LEAP 300C (300 Hz) excimer lasers were used. Pulse energy was in the 500-1000 mJ range.
[0082] To ensure the formation of the Y.sub.2O.sub.3 phase in the YBCO matrix, ceramic targets were used that were enriched with yttrium oxide comparing to the YBa.sub.2Cu.sub.3O.sub.7 stoichiometric composition. The target composition was chosen so that the superconductor layer of RE.sub.1+2xBa.sub.2Cu.sub.3O.sub.7+3x overall composition, where x=0.05 and x=0.15 would be obtained.
[0083] The deposition zone was confined by substrate 1, target 4 and shields 6 that protect the equipment from the material ablated from the target. In this regard, “temperature gradient in the deposition zone” means the temperature gradient between substrate 1 and target 4, and between substrate 1 and shields 6.
[0084] The substrate tape was moved helically through the deposition zone in several parallel lanes (4-6), in order to increase the utilization of the ablated material onto the tape and obtain a HTS film of a sufficient thickness; however, this is not a required condition for fabricating the superconductor layer.
[0085] Uniform multiphase sintered ceramic target 4 was cooled at the side opposite to the side irradiated with excimer laser beam 2, to a temperature in the 20-200° C. range. The temperature of shields 6 was in the 200-400° C. range. The distance from the shields to the metal tape was from 4 to 8 cm. Thus, average temperature gradient was from (800−400)/8=50° C./cm to (1100−200)/4=225° C./cm. The target ablation takes place under the continuous scanning of the focused laser beam over the target surface, to ensure the uniform distribution of the material in the deposition zone. The local deposition rate onto the substrate was at least 100 nm/s.
[0086] Pulsed laser deposition was performed to reach the pre-determined thickness of the superconductor layer. To achieve that, we adjusted the required number of tape passes through the deposition zone and the tape motion speed.
[0087] Table 1 lists the composition of superconductor layers and processing conditions used to fabricate the layers, as well as corresponding values of critical current at 77 K in self-field and at 4.2 and 20 K in 20 T magnetic field, and the values of lift-factors at 4.2 and 20 K in 20 T magnetic field.
[0088]
[0089] The following two orientations were established by the fast Fourier transform analysis of the transmission electron microscopy (TEM) images: [100](001)Y.sub.2O.sub.3//[110](001)YBCO and (110)Y.sub.2O.sub.3//[010](001)YBCO; this agrees with the x-ray diffraction results.
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[0091] (001)-oriented Y.sub.2O.sub.3 nanoparticles are usually of anisotropic shape but are elongated along the (001)YBCO plane.
[0092] In some cases, at a lower magnification (
[0093] Average concentration density of the nanoparticles throughout the entire film thickness is 2.5*10.sup.17 nanoparticles/cm.sup.3.
[0094] We tested the claimed technology in pilot production of flexible HTS. Pulsed laser deposition of the superconductor layer was performed according to the present invention. We fabricated over 600 km of HTS conductor based on YBCO using this technology; this allowed us to perform a comprehensive statistical study of the fabricated flexible HTS.
[0095]
[0096] Due to the structural anisotropy of YBCO, I.sub.c depends on the magnetic field direction.
[0097] Table 2 shows magnetic field dependences (B//c) of average lift-factor values for 4.2 and 20 K, for a set of 200 samples from industrially fabricated conductor based on YBCO with Y.sub.2O.sub.3 nanoparticles.
[0098]
[0099] It is the embodiment of this invention in pilot production that made practically possible the creation in 5-10 years of compact fusion reactors with plasma confinement by magnetic fields over 10 T.
[0100] All measurements were performed according to the following procedures.
[0101] Positional non-contact measurements of critical current at 77 K in self-field were performed along the entire length of each wire with a TapeStar XL machine, with a longitudinal resolution of 2 mm. As-measured non-contact I.sub.c data for each wire were calibrated by the standard 4-contact transport DC measurements, using a 1 μV/cm criterion for I.sub.c. The critical current at 77 K in self-field was 175 A (437 A/cm), averaged over the entire wire lot. The best 10% of wires had an I.sub.c of over 200 A (500 A/cm).
[0102] YBCO film thickness was determined gravimetrically by weighing three 30 cm long pieces of 12 mm wide wire before and after dissolving the HTS layer in 5% nitric acid, according to patent RU 2687312.
[0103] Transmission electron microscopy (TEM) images were taken in an Osiris TEM/STEM (Thermo Fisher Scientific, USA) equipped with a high angle annular dark field (HAADF) electron detector (Fischione, USA) and Bruker energy-dispersive X-ray microanalysis (ERA) system (Bruker, USA) at an accelerating voltage of 200 kV. Image processing was performed using Digital Micrograph (Gatan, USA) and TIA (ThermoFisher Scientific, USA) software.
[0104] The measurements of critical current in high magnetic field were performed in independent laboratories equipped with appropriate facilities: National High Magnetic Field Laboratory (NHMFL), Tallahassee, USA; University of Geneva, Switzerland, and Tohoku University, Japan.
[0105] High-field measurements at NHMFL were performed on full 4 mm width samples in two magnets. For in-field experiments up to 15 T, used the Oxford Instruments 15 T/17 T magnet system with a 52 mm cold bore was used. Samples were immersed in liquid helium during experiments at 4.2 K. Samples were in helium gas during experiments at 20 K. In experiments up to 31.2 T used the NHMFL resistive magnet system (cell 7) was used with a 50 mm bore magnet; 38 mm in Janis cryostat.
[0106] The experimental setup at the University of Geneva allows measuring I.sub.c up to 2 kA at 4.2 K in liquid He and up to 1 kA in He gas flow by standard four-probe measurement. A 19 T (at 4.2 K)/21 T (at 2.2 K) superconducting solenoid magnet from Bruker BioSpin completes the system. A temperature precision down to ±0.01 K is achieved in He gas flow up to 50 K using an active temperature stabilization system which compensates the heating during current runs with PID controlled heaters.
[0107] The I.sub.c(B, T, θ) data collection in High Field Laboratory for Superconducting Materials at Tohoku University was carried out using 30 um and 40 um bridges of 1 mm length fabricated by picosecond laser micromachining from the 4 mm tapes with the top Ag layer. The measurements were performed at 77, 65, 40, 20 and 4.2 K using 20T-CSM and 25T-CSM cryogen-free superconducting magnets. The angular dependence I.sub.c(θ) data were collected in the range from −45° to 120°.
[0108] We used the so-called “lift-factor” methodology in our result analysis. Lift-factor is a simple empirical I.sub.c scaling parameter: it is defined as the ratio of a sample's I.sub.c at a specific temperature and magnetic field to the I.sub.c of the same sample at 77 K in self-field.
[0109] The above data show that flexible superconductor according to the invention demonstrates extremely high values of critical current in high magnetic fields. Moreover, claimed technology proved excellent in pilot industrial manufacturing of flexible superconductors with robust and stable properties. We attribute the great stability of our commercial production to our choice of native RE.sub.2O.sub.3 nanoparticles as dominant pinning centers. They do not increase the chemical complexity of REBCO and they impart a simple, uniform nanostructure, amenable to reproducible fabrication.
[0110] Especially important is that we obtain these extraordinarily high values not in select champion samples but in hundreds of kilometers of routinely manufactured, commercially available flexible high temperature superconductor.
TABLE-US-00001 TABLE 1 Sample # 1 2 Superconductor Overall composition of x = 0.05 x = 0.15 HTS layer Y.sub.1+2xBa.sub.2Cu.sub.3O.sub.7+3x HTS layer thickness (microns) 2.3 2.4 Texture of Y.sub.2O.sub.3 nanoparticles (001) and (110) (001) and (110) Concentration density of Y.sub.2O.sub.3 0.7*10.sup.17-3.2*10.sup.17 1.9*10.sup.17-5.9*10.sup.17 nanoparticles (nanoparticles/cm.sup.3) Size of Y.sub.2O.sub.3 nanoparticles (nm) (110) Y.sub.2O.sub.3:~5 (110) Y.sub.2O.sub.3:~5 (001) Y.sub.2O.sub.3: (001) Y.sub.2O.sub.3: (10-30)*5 (10-30)*5 Distribution of Y.sub.2O.sub.3 (110) Y.sub.2O.sub.3: (110) Y.sub.2O.sub.3: nanoparticles in the matrix uniform uniform (001) Y.sub.2O.sub.3: partly (001) Y.sub.2O.sub.3: partly uniform, partly uniform, partly assembled in layers assembled in layers parallel to the (001) parallel to the (001) YBCO plane YBCO plane Superconductor Substrate temperature (° C.) 800 850 fabrication Temperature gradient (° C./cm) 75 200 parameters Laser pulse repletion rate (Hz) 200 300 Pulse energy (mJ) 500 1000 Deposition rate (nm/s) 100 300 Properties Critical current at 77K 430 440 in self-field (A/cm width) Critical current at 20K, 20 T 495 585 (A/cm width) Lift-factor at 20K, 20 T 1.15 1.33 Critical current at 4.2K, 20 T 1054 1170 (A/cm width) Lift-factor at 4.2K, 20 T 2.45 2.66
TABLE-US-00002 TABLE 2 Average lift-factor Average lift-factor B//c value at 4.2K ± value at 20K ± (T) standard deviation standard deviation 0 17.50 ± 2.13 13.23 ± 1.72 1 11.69 ± 1.63 6.96 ± 1.19 2 8.79 ± 1.24 4.93 ± 0.86 3 7.32 ± 1.04 4.14 ± 0.76 4 6.52 ± 0.91 3.61 ± 0.66 5 5.76 ± 0.80 3.21 ± 0.59 6 5.27 ± 0.73 2.92 ± 0.54 7 4.93 ± 0.67 2.67 ± 0.49 8 4.60 ± 0.60 2.45 ± 0.44 9 4.32 ± 0.56 2.21 ± 0.38 10 4.07 ± 0.51 2.05 ± 0.35 11 3.85 ± 0.48 1.92 ± 0.32 12 3.64 ± 0.45 1.79 ± 0.30 13 3.46 ± 0.43 1.68 ± 0.27 14 3.29 ± 0.39 1.57 ± 0.26 15 3.13 ± 0.36 1.48 ± 0.24 16 3.00 ± 0.34 1.40 ± 0.22 17 2.86 ± 0.31 1.32 ± 0.21 18 2.75 ± 0.31 1.25 ± 0.20 19 2.64 ± 0.28 1.19 ± 0.16 20 2.55 ± 0.27 1.13 ± 0.17