The work investigates influence of the electrolyte conductivity on the onset of partial contact glow discharge electrolysis(CGDE)in a water electrolysis.Critical current density(CCD)and breakdown voltage were measured...The work investigates influence of the electrolyte conductivity on the onset of partial contact glow discharge electrolysis(CGDE)in a water electrolysis.Critical current density(CCD)and breakdown voltage were measured together with in situ observation of hydrogen bubble behavior,whose influence has not been focused on.For a fixed current during normal electrolysis,hydrogen coalescence adjacent to cathode surface was invigorated at a lower conductivity.Photographic analyses elucidated the hydrogen coalescence characteristics by quantifying size and population of detached hydrogen bubbles.The CCD increased about 104% within given range of conductivity(11.50-127.48 mS·cm^(-1))due to impaired bubble coalescence,which delays hydrogen film formation on the cathode.Meanwhile,decreasing trend of breakdown voltage was measured with increased conductivity showing maximum drop of 74%.It is concluded that onset of partial CGDE is directly affected by hydrodynamic bubble behaviors,whereas the electrolyte conductivity affects the bubble formation characteristics adjacent to cathode electrode.展开更多
Since Bi2Sr2Ca1Cu2O8＋x（Bi2212） wires are subject to mechanical loadings, degradation of critical current will occur. The effect of compressive loadings on the critical current of Bi2212 wire is studied by consideri...Since Bi2Sr2Ca1Cu2O8＋x（Bi2212） wires are subject to mechanical loadings, degradation of critical current will occur. The effect of compressive loadings on the critical current of Bi2212 wire is studied by considering micro-buckling of filament. A Bi2212 wire is regarded as a unidirectional filament-reinforced composite in the theoretical analysis. By considering the influence of inclusion, the micro-buckling wavelength can be derived by using a two-dimensional model. Based on the experimental results, the critical current is fitted as a function of buckling wavelength. It is found that the decrease of the critical current is directly proportional to the reciprocal of square of the buckling wavelength. Change of micro-buckling wavelength with material parameters is discussed. A critical strain in the wire with a filament bridge is analyzed using the finite element method.展开更多
Garnet-type solid-state batteries(SSBs)are considered to be one of the most promising candidates to realize next-generation lithium metal batteries with high energy density and safety.However,the dendrite-induced shor...Garnet-type solid-state batteries(SSBs)are considered to be one of the most promising candidates to realize next-generation lithium metal batteries with high energy density and safety.However,the dendrite-induced short-circuit and the poor interfacial contact impeded the practical application.Herein,interface engineering to achieve low interfacial resistance without high temperature calcination was developed,which Li_(6.4)La_(3)Zr_(1.4)Ta_(0.6)O_(12)(LLZTO)was simply coated with complex hydride(Li_(4)(BH_(4))_(3)I(3L1L))in various mass ratios n(Li_(4)(BH_(4))_(3)I)-(100−n)LLZTO(10≤n≤40).The interfacial conductivity increases by more than three orders of magnitude from 8.29×10^(−6)S·cm^(−1)to 1.10×10^(−2)S·cm^(−1).Symmetric Li cells exhibit a high critical current density(CCD)of 4.0 mA·cm^(−2) and an excellent cycling stability for 200 h at 4.0 mA·cm^(−2).SSBs with polymeric sulfur-polyacrylonitrile(SPAN)cathode achieve a high discharge capacity of 1149 mAh·g^(−1) with a capacity retention of 91%after 100 cycles(0.2 C).This attempt guides a simple yet efficient strategy for obtaining a stable Li/LLZTO interface,which would promote the development of solid-state batteries.展开更多
In this work,we discuss the origin of several anomalies present in the point-contact Andreev reflection spectra of（Li1-xFex）OHFeSe,LiTi2O4,and La2-xCexCuO4.While these features are similar to those stemming from int...In this work,we discuss the origin of several anomalies present in the point-contact Andreev reflection spectra of（Li1-xFex）OHFeSe,LiTi2O4,and La2-xCexCuO4.While these features are similar to those stemming from intrinsic superconducting properties,such as Andreev reflection,electron-boson coupling,multigap superconductivity,d-wave and p-wave pairing symmetry,they cannot be accounted for by the modified Blonder–Tinkham–Klapwijk（BTK） model,but require to consider critical current effects arising from the junction geometry.Our results point to the importance of tracking the evolution of the dips and peaks in the differential conductance as a function of the bias voltage,in order to correctly deduce the properties of the superconducting state.展开更多
Ag-sheathed BiPbSrCaO(2223)superconducting tapes prepared by the powder-in-tube technique were inVeSgated. The Mswt of M layCr and the Jc at 77 K are spengly dspendent on the amouDt of cold wotheg and annchg condition...Ag-sheathed BiPbSrCaO(2223)superconducting tapes prepared by the powder-in-tube technique were inVeSgated. The Mswt of M layCr and the Jc at 77 K are spengly dspendent on the amouDt of cold wotheg and annchg condition. The Jc bo by uhahal tw aha drawing and rolling. The OPbown annwtg theperawt, boe and coohag de tO madrihe Jc vaiueS were in the range 84()-- 850t, 1bo^2bo h and 50-- loot / h, nyhvejy. The mndum tuSPOrt Jt at 77 K under zero mopetic field was l.33 x l04 A / cm2.展开更多
YBCO bulk superconductors were prepared by the solid state reaction andtop-seed-melt-textured growth (TSMTG) process. By using the AC susceptibility measurement, thecritical transition temperature T_c of samples is 91...YBCO bulk superconductors were prepared by the solid state reaction andtop-seed-melt-textured growth (TSMTG) process. By using the AC susceptibility measurement, thecritical transition temperature T_c of samples is 91.5 K for the highest value, and the transitionwidth ΔT_c is less than 1 K. The highest magnetization critical current densities J_c achieved 10~6A/cm^2 under 5 T at 10 K and 1.35X10^4 A/cm^2 under 2 T at 70 K (H//c), respectively. The resultscombining the SEM observation indicate that doping of Y211 particles is more effective in improvingthe growth quality of melt-textured YBCO superconductor and in reducing the micro-cracks ofspecimens. Doping of Y_2O_3 powder forms the rod-shaped Y211 particles, but doping of Y211 particlesdirectly to matrix materials forms the spherical Y211 particles mainly. Combining themicrostructures with J_c measurements shows that the interfaces are most important on flux bundlepinning, in which the gradient of free energy is larger than that of other place between the Y211particles and the Y123 matrix materials.展开更多
The high-entropy alloy(HEA)superconductor,Ta_(1/6)Nb_(2/6)Hf_(1/6)Zr_(1/6)Ti_(1/6)(Ta-Nb-Hf-Zr-Ti),is systematically studied to examine changes in superconducting critical properties,critical temperature(T_(c)),critic...The high-entropy alloy(HEA)superconductor,Ta_(1/6)Nb_(2/6)Hf_(1/6)Zr_(1/6)Ti_(1/6)(Ta-Nb-Hf-Zr-Ti),is systematically studied to examine changes in superconducting critical properties,critical temperature(T_(c)),critical cur-rent density(J_(c)),and upper critical field(H_(c2)),concerning thermal treatment conditions.Annealing condi-tion affects Jc more significantly than T_(c)and H_(c2),with a large improvement of flux pinning force density(F_(p)).The Jc of bare sample is reduced to 10 A cm^(-2)at an applied magnetic field of approximately 1.5 T,whereas the sample annealed at 550℃for 12 h exhibits J_(c)>100 kA cm^(-2)up to around 4 T.Furthermore,the Vickers hardness(HVIT)of the Ta-Nb-Hf-Zr-Ti HEA superconductor notably increases from∼384 to 528 HVIT following a 24-h annealing at 500℃.These results demonstrate that thermal annealing is a powerful process to optimize both the superconducting and mechanical properties of high-entropy alloy superconductors.展开更多
The critical current density Jc is one of the most important parameters of high temperature superconducting films in superconducting applications, such as superconducting filter and superconducting Josephson devices. ...The critical current density Jc is one of the most important parameters of high temperature superconducting films in superconducting applications, such as superconducting filter and superconducting Josephson devices. This paper presents a new model to describe inhomogeneous current distribution throughout the thickness of superconducting films applying magnetic field by solving the differential equation derived from Maxwell equation and the second London equation. Using this model, it accurately calculates the inductive third-harmonic voltage when the film applying magnetic field with the inductive measurement for Jc. The theoretic curve is consistent with the experimental results about measuring superconducting film, especially when the third-harmonic voltage just exceeds zero. The Jc value of superconducting films determined by the inductive method is also compared with results raeasured by four-probe transport method. The agreements between inductive method and transport method are very good.展开更多
A promising method —“powder in tube”technique was used to fabricate Ag-sheathed Bi-2223 superconductive tapes with high critical current density.After a combination processing of pressing and subsequent heat treatm...A promising method —“powder in tube”technique was used to fabricate Ag-sheathed Bi-2223 superconductive tapes with high critical current density.After a combination processing of pressing and subsequent heat treatment,we obtained tapes with high degree of texture,good compaction and uniform properties.At 77 K in zero field,J_C was higher than 1×10~4 A/cm^2 while the highest J_C was 1.69×10~4 A/cm^2.SEM and XRD was used to detect the tapes texture,and the relationship be- tween J_C and the degree of texture is discussed.In addition,the reason for obstacling the improvement of J_C is also investigated.展开更多
Apparent critical current density(j_(Ac)^(a))of garnet all-solid-state lithium metal symmetric cells(ASSLSCs)is a fundamental parameter for designing all-solid-state lithium metal batteries.Nevertheless,how much the p...Apparent critical current density(j_(Ac)^(a))of garnet all-solid-state lithium metal symmetric cells(ASSLSCs)is a fundamental parameter for designing all-solid-state lithium metal batteries.Nevertheless,how much the possible maximum apparent current density that a given ASSLSC system can endure and how to reveal this potential still require study.Herein,a capacity perturbation strategy aiming to better measure the possible maximum j_(Ac)^(a)is proposed for the first time.With garnet-based plane-surface structure ASSLSCs as an exemplification,the j_(Ac)^(a)is quite small when the capacity is dramatically large.Under a perturbed capacity of 0.001 mA h cm^(-2),the j_(Ac)^(a)is determined to be as high as 2.35 mA cm^(-2)at room temperature.This investigation demonstrates that the capacity perturbation strategy is a feasible strategy for measuring the possible maximum j_(Ac)^(a)of Li/solid electrolyte interface,and hopefully provides good references to explore the critical current density of other types of electrochemical systems.展开更多
Temperature dependence of tbe pair-breaking critical current density of MgB2, jd（T）, is studied using a two-band Ginzburg-Landau theory. The results are shown to be in good agreement with experimental data for the s...Temperature dependence of tbe pair-breaking critical current density of MgB2, jd（T）, is studied using a two-band Ginzburg-Landau theory. The results are shown to be in good agreement with experimental data for the superconducting magnesium diboride MgB2.展开更多
High-temperature superconducting(HTS)rare-earth Ba_(2)Cu_(3)O_(7-x)(REBCO)coated conductors(CCs)have significant potential in high-current and high-field applications.However,owing to the weak interface strength of th...High-temperature superconducting(HTS)rare-earth Ba_(2)Cu_(3)O_(7-x)(REBCO)coated conductors(CCs)have significant potential in high-current and high-field applications.However,owing to the weak interface strength of the laminated composite REBCO CCs,the damage induced by the thermal mismatch stress under a combination of epoxy impregnation,cooling,and quenching can cause premature degradation of the critical current.In this study,a three-dimensional(3D)electromagnetic-thermal-mechanical model based on the H-formulation and cohesive zone model(CZM)is developed to study the critical current degradation characteristics in an epoxy-impregnated REBCO CC caused by the damage during a quench.The temperature variation,critical current degradation of the REBCO CC,and its degradation onset temperature calculated by the numerical model are in agreement with the experimental data taken from the literature.The delamination of the REBCO CC predicted by the numerical model is consistent with the experimental result.The numerical results also indicate that the shear stress is the main contributor to the damage propagation inside the REBCO CC.The premature degradation of the critical current during a quench is closely related to the interface shear strength inside the REBCO CC.Finally,the effects of the coefficient of thermal expansion(CTE)of the epoxy resin,thickness of the substrate,and substrate material on the critical current degradation characteristics of the epoxy-impregnated REBCO CC during a quench are also discussed.These results help us understand the relationship between the current-carrying degradation and damage in the HTS applications.展开更多
The strain effect on the critical current is one of the most important properties for polycrystalline YBa2 Cu3O7-δ （REBCO, RE： rare earth） films, in which the reversible effect is intrinsic in the range of strain ...The strain effect on the critical current is one of the most important properties for polycrystalline YBa2 Cu3O7-δ （REBCO, RE： rare earth） films, in which the reversible effect is intrinsic in the range of strain 0 and the irreversible strain εirr. By introducing the applied strain, a modified grain boundaries （GBs） in the REBCO film is developed. lattice model combining the strain and misorientation of A good agreement of the calculation on the lattice model with the experimental data shows that the lattice model is able to well describe the reversible effect of axial strain on the critical current of the REBCO film, and provides a good understanding of the mechanism of the reversible effect of the strain. Moreover, the effects of the crystallographic texture of the REBCO film and the residual strain εr on the variation of the critical current with the applied strain are extensively investigated. Furthermore by using the developed lattice model, the irreversible strain εirr of the REBCO film can be theoretically determined by comparing the calculation of the critical current-strain curve with the experimental data.展开更多
The empirically reported values of the critical current density (j<sub>c</sub>) of Bi-2212 as 2.4 × 10<sup>5</sup> (j<sub>c</sub><sub>1</sub>;Sample 1) and 1.0 ...The empirically reported values of the critical current density (j<sub>c</sub>) of Bi-2212 as 2.4 × 10<sup>5</sup> (j<sub>c</sub><sub>1</sub>;Sample 1) and 1.0 × 10<sup>6</sup> A/cm<sup>2</sup> (j<sub>c</sub><sub>2</sub>;Sample 2) are intriguing because both of them correspond to the same values of the temperature T = 4.2 K and the applied magnetic field H = 12 × 10<sup>4</sup> G. This difference is conventionally attributed to such factors—not all of which are quantifiable—as the geometry, dimensions and the nature of dopants and the manners of preparation of the samples which cause their granular structures, grain boundaries, alignment of the grains and so on to differ. Based on the premise that the chemical potential μ subsumes most of these features, given herein is a novel explanation of the said results in terms of the values of μ of the two samples. This paper revisits the problem that was originally addressed in [Malik G.P., Varma V.S. (2020) WJCMP, 10, 53-70] in the more accurate framework of a subsequent paper [Malik G.P., Varma V.S. (2021) JSNM, 34, 1551-1561]. Besides, it distinguishes between the contributions of the electro-electron (e-e) and the hole-hole (h-h) pairs to j<sub>c</sub>—a feature to which no heed was paid earlier. The essence of our findings is that the j<sub>c</sub>s of the two samples differ because they are characterized by different values of the primary variables μ<sub>i</sub><sub> </sub>and <img src="Edit_e1b831e9-dc51-4c3b-bd84-fa905e3e62b5.png" alt="" />, where <img src="Edit_1f775a80-30ab-447d-861f-afb4ba8fba6a.png" alt="" /> is the effective mass of a charge-carrier and m<sub>e</sub><sub> </sub>is the free-electron mass and i = 1 and 2 denote Sample 1 and Sample 2, respectively. In the scenario of the charge-carriers being predominantly h-h pairs, the values of these parameters are estimated to be: μ<sub>1</sub> ≈ 12.3 meV, η<sub>1</sub> ≈ 0.58;μ<sub>2</sub> ≈ 22.7 meV, η<sub>2</sub> ≈ 0.94. Following from these and similar estimates when the charge-carriers are e-e pairs, given below for each sample are the detailed results for the values of the secondary variables viz. the number density of the charge-carriers and their critical velocity, the number of occupied Landau levels and the magnetic interaction parameter.展开更多
It is very important for high temperature superconducting electronic devices to increase the grain size of YBCO epitaxial films because it can effectively reduce the defects and improve the probability of successful p...It is very important for high temperature superconducting electronic devices to increase the grain size of YBCO epitaxial films because it can effectively reduce the defects and improve the probability of successful preparation of Josephson junction.In this study,YBa_(2)Cu_(3)O_(7-δ)(YBCO)films with grain size in excess of 1.5μm were successfully prepared by the directly heating SrTiO_(3)substrates coated by Si C on their back.Interestingly,the grain size of YBCO film is enhanced greatly by this directly heating method,and the critical temperature TCand critical current density JCof YBCO films are as high as 91.5 K and 3.5 MA/cm^(2),respectively.Compared with the traditional indirect heating method,which involves applying silver paste and then using a heat soaking block(e.g.Inconel 600),this direct heating method effectively enhances the grain size of YBCO film and the possibility of successful preparation of Josephson junction.展开更多
The fabrication of high-quality YBa_(2)Cu_(3)O_(7)−δ(YBCO)nanowires has garnered significant attention in the field of high-temperature superconductivity due to their potential applications in quantum communication,d...The fabrication of high-quality YBa_(2)Cu_(3)O_(7)−δ(YBCO)nanowires has garnered significant attention in the field of high-temperature superconductivity due to their potential applications in quantum communication,deep space exploration,and various other fields.Cl_(2)-assisted reactive ion etching(RIE)stands out as a more effective and efficient method for patterning scalable thin films.However,neither RIE nor high-density RIE has achieved superconducting YBCO nanowires with a width smaller than 3μm.Here,we delve into the factors that limit the line width of Cl_(2)-assisted inductively coupled plasma reactive ion etching(ICP-RIE)processing and the method to elimiate them.Our approach involves utilizing Cl_(2)/Ar as etching gas and incorporating a specialized vacuum heating process after etching.Our experimental results demonstrate the successful realization of 10 nm-thick YBCO nanowires with widths as small as 0.15μm,exhibiting excellent performance in terms of their intrinsic superconducting properties.The mechanism is evidenced by X-ray photoelectron spectroscopy(XPS)analysis in comparison of nanowires with and without heating treatment,in which the residual Cl_(2) on the sidewall of nanowires evaporates and oxidizes Cu^(+)back into Cu^(2+)in an unetched state.展开更多
The Josephson effect,an important quantum supercurrent phenomenon,has been extensively studied in superconductors and superfluids.In this paper,we investigate the rich physics of one-dimensional Josephson junctions in...The Josephson effect,an important quantum supercurrent phenomenon,has been extensively studied in superconductors and superfluids.In this paper,we investigate the rich physics of one-dimensional Josephson junctions in a red-detuned optical lattice with sodium(Na)quantum gas.A one-dimensional Josephson array is formed by setting up an optical lattice using a red-detuned laser.By characterizing the dependence of Josephson oscillations of the lattice depth,we experimentally demonstrate the Josephson current.The lattice depth is controlled by altering the lattice power,and our observations are consistent with theoretical predictions.These findings offer valuable insights into quantum coherent transport and the intricate dynamics inherent to superfluidity.展开更多
Magnetic levitation of the fusion target by coating a thin MgB_(2)superconducting shell on its outer surface has recently been proposed in inertial confinement fusion(ICF)to realize a noncontact support of the target ...Magnetic levitation of the fusion target by coating a thin MgB_(2)superconducting shell on its outer surface has recently been proposed in inertial confinement fusion(ICF)to realize a noncontact support of the target at~20 K to boost the implosion performance and fusion yield.To avoid possible effects on target ablation,the coated MgB_(2)shell is anticipated to be as thin as possible while fulfilling the target levitation requirements.Under this circumstance,the fabrication of an MgB_(2)shell with reduced thickness has been explored using a hybrid physical-chemical vapour deposition method.By gradually decreasing the deposition time,a set of MgB_(2)shells were grown on 1 mm diameter Si_(3)N_(4)spheres with the thickness reducing from 720 nm to 200 nm.The spherical shells all have a polycrystalline structure characterized by closely packed hexagonal grains,with both the grain size and thickness diminishing as the shell thickness decreases.The superconducting transition temperature Tcof the shells,as determined by both resistance and magnetization measurements,is in the range of 38-40 K and all shells exhibit ideal diamagnetism at low temperatures.For the thinnest shell of 200 nm,the superconducting critical current density Jcat 20 K reaches 8.0×10^(6)A/cm^(2)and 2.1×10^(5)A/cm^(2)under zero and 2 T applied field,respectively.The results indicate that it is experimentally feasible to fabricate MgB_(2)spherical shells with a thickness as low as 200 nm while maintaining the high Tcand Jc,thereby taking a further step towards the application of the shell in superconducting magnetic levitation for ICF.展开更多
In this work,bulk-Nb_(3)Sn superconductors were prepared by the powder metallurgy route under the heat treatment conditions of rapid-heating and short-holding and the effect of Cu content and rapid-heating process on ...In this work,bulk-Nb_(3)Sn superconductors were prepared by the powder metallurgy route under the heat treatment conditions of rapid-heating and short-holding and the effect of Cu content and rapid-heating process on the microstructure and superconducting properties of bulk-Nb_(3)Sn superconductors were systematically investigated.The results showed that both of critical temperature(Tc)and critical current density(Jc)of bulk samples got decreased with increasing Cu content.The rapid-heating and short-holding process exhibited a'healing'effect on the holes in Nb_(3)Sn layers,significantly improving the compactness of the bulk samples.Moreover,the bulk sample,which was heat treated at 600℃for 50 h,then induction heated to 1000℃and isothermally held for 20 s,exhibited the highest Jc,non-Cu values of 2.38×10^(9)A/m^(2)(at 4.2 K&6 T).And this could be attributed to the small average grain size,high content of Nb_(3)Sn superconducting phase,and the Cu(Sn)artificial pinning centers in the Nb_(3)Sn layer.Besides,Nb_(3)Sn wire by internal-tin method was processed using the same heat treatment schedule to validate the effectiveness of the rapid-heating process.The critical current(Ic)of the wire sample,measured via V-I characteristic curve at 4.2 K&6 T,was determined to be 96 A,corresponding to a Jc,layer value of 4593 A/mm^(2).Moreover,a Jc,non-Cu model(J_(c,non-Cu)=4985·x^(3.5)+0.466[-10-30 exp(0.00348/y)+577y]^(0.5)+45·e-z/175)⎠concerning with the microstructural parameters(x:superconducting phase content,y:average Sn content in Nb_(3)Sn layer,and z:grain size of Nb_(3)Sn)was proposed,providing a semi-quantitative reference to describe the Jc,non-Cu of bulk-Nb_(3)Sn superconductors.Finally,it should be noted that the relevant conclusions in this work regarding the kinetics of rapid-heating and microstructural evolution of bulk samples may require adjustment or further validation when applied to the structure of wires.展开更多
After discovering high temperature superconducting materials 20 years ago, the preparation of applicable HTS materials has been pursued along with HTS mechanism and characteristic study. At present, the focus on the a...After discovering high temperature superconducting materials 20 years ago, the preparation of applicable HTS materials has been pursued along with HTS mechanism and characteristic study. At present, the focus on the applied HTS technology has been moving to the industrial preparations from the laboratory research stage, and the technology has been well verified for practical applications from small to large scales. The fabrication techniques of engineering HTS materials are being industrialized; and various HTS devices are also on the way towards practical applications. This paper provides a comprehensive summary on the applied high temperature superconductivity with regard to various applicable HTS materials, their preparation techniques and charac- terization, and applications in a wide range.展开更多
基金sponsored by the Korean Ministry of Science and ICT(MSIT)supported by nuclear Research&Development program grant funded by the National Research Foundation(NRF)(2021M2D1A1084838)。
文摘The work investigates influence of the electrolyte conductivity on the onset of partial contact glow discharge electrolysis(CGDE)in a water electrolysis.Critical current density(CCD)and breakdown voltage were measured together with in situ observation of hydrogen bubble behavior,whose influence has not been focused on.For a fixed current during normal electrolysis,hydrogen coalescence adjacent to cathode surface was invigorated at a lower conductivity.Photographic analyses elucidated the hydrogen coalescence characteristics by quantifying size and population of detached hydrogen bubbles.The CCD increased about 104% within given range of conductivity(11.50-127.48 mS·cm^(-1))due to impaired bubble coalescence,which delays hydrogen film formation on the cathode.Meanwhile,decreasing trend of breakdown voltage was measured with increased conductivity showing maximum drop of 74%.It is concluded that onset of partial CGDE is directly affected by hydrodynamic bubble behaviors,whereas the electrolyte conductivity affects the bubble formation characteristics adjacent to cathode electrode.
基金Project supported by the National Natural Science Foundation of China(Nos.11327802,11472120,and 11421062)the National Key Project of Magneto-Constrained Fusion Energy Development Program(No.2013GB110002)the Fundamental Research Funds for the Central Universities(No.lzujbky-2017-k18)
文摘Since Bi2Sr2Ca1Cu2O8＋x（Bi2212） wires are subject to mechanical loadings, degradation of critical current will occur. The effect of compressive loadings on the critical current of Bi2212 wire is studied by considering micro-buckling of filament. A Bi2212 wire is regarded as a unidirectional filament-reinforced composite in the theoretical analysis. By considering the influence of inclusion, the micro-buckling wavelength can be derived by using a two-dimensional model. Based on the experimental results, the critical current is fitted as a function of buckling wavelength. It is found that the decrease of the critical current is directly proportional to the reciprocal of square of the buckling wavelength. Change of micro-buckling wavelength with material parameters is discussed. A critical strain in the wire with a filament bridge is analyzed using the finite element method.
基金This study was financially supported by the National Natural Science Foundation of China(Nos.52171180,51802154,and 51971065)the National Science Fund for Distinguished Young Scholars(No.51625102)+3 种基金the Innovation Program of Shanghai Municipal Education Commission(No.2019-01-07-00-07-E00028)the Fundamental Research Funds for the Central Universities(No.NG2022005)the Open Fund for Graduate Innovation Base in Nanjing University of Aeronautics and Astronautics(No.xcxjh20210612)partially supported by the Fundamental Research Funds for the Central Universities,NS2021043.
文摘Garnet-type solid-state batteries(SSBs)are considered to be one of the most promising candidates to realize next-generation lithium metal batteries with high energy density and safety.However,the dendrite-induced short-circuit and the poor interfacial contact impeded the practical application.Herein,interface engineering to achieve low interfacial resistance without high temperature calcination was developed,which Li_(6.4)La_(3)Zr_(1.4)Ta_(0.6)O_(12)(LLZTO)was simply coated with complex hydride(Li_(4)(BH_(4))_(3)I(3L1L))in various mass ratios n(Li_(4)(BH_(4))_(3)I)-(100−n)LLZTO(10≤n≤40).The interfacial conductivity increases by more than three orders of magnitude from 8.29×10^(−6)S·cm^(−1)to 1.10×10^(−2)S·cm^(−1).Symmetric Li cells exhibit a high critical current density(CCD)of 4.0 mA·cm^(−2) and an excellent cycling stability for 200 h at 4.0 mA·cm^(−2).SSBs with polymeric sulfur-polyacrylonitrile(SPAN)cathode achieve a high discharge capacity of 1149 mAh·g^(−1) with a capacity retention of 91%after 100 cycles(0.2 C).This attempt guides a simple yet efficient strategy for obtaining a stable Li/LLZTO interface,which would promote the development of solid-state batteries.
基金Project supported by the National Key Basic Research Program of China(Grant Nos.2015CB921000,2016YFA0300301,and 2017YFA0302902)the National Natural Science Foundation of China(Grant Nos.11674374 and 1474338)+5 种基金the Key Research Program of Frontier Sciences,Chinese Academy of Sciences(Grant No.QYZDB-SSW-SLH008)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant Nos.XDB07020100 and XDB07030200)the Beijing Municipal Science and Technology Project(Grant No.Z161100002116011)the Fonds de la Recherche Scientifique–FNRS and the ARC Grant 13/18-08 for Concerted Research Actions,financed by the French Community of Belgium(Wallonia-Brussels Federation)Jérémy Brisbois acknowledges the support from F.R.S.–FNRS(Research Fellowship)The work of Alejandro V Silhanek is partially supported by PDR T.0106.16 of the F.R.S.–FNRS
文摘In this work,we discuss the origin of several anomalies present in the point-contact Andreev reflection spectra of（Li1-xFex）OHFeSe,LiTi2O4,and La2-xCexCuO4.While these features are similar to those stemming from intrinsic superconducting properties,such as Andreev reflection,electron-boson coupling,multigap superconductivity,d-wave and p-wave pairing symmetry,they cannot be accounted for by the modified Blonder–Tinkham–Klapwijk（BTK） model,but require to consider critical current effects arising from the junction geometry.Our results point to the importance of tracking the evolution of the dips and peaks in the differential conductance as a function of the bias voltage,in order to correctly deduce the properties of the superconducting state.
文摘Ag-sheathed BiPbSrCaO(2223)superconducting tapes prepared by the powder-in-tube technique were inVeSgated. The Mswt of M layCr and the Jc at 77 K are spengly dspendent on the amouDt of cold wotheg and annchg condition. The Jc bo by uhahal tw aha drawing and rolling. The OPbown annwtg theperawt, boe and coohag de tO madrihe Jc vaiueS were in the range 84()-- 850t, 1bo^2bo h and 50-- loot / h, nyhvejy. The mndum tuSPOrt Jt at 77 K under zero mopetic field was l.33 x l04 A / cm2.
文摘YBCO bulk superconductors were prepared by the solid state reaction andtop-seed-melt-textured growth (TSMTG) process. By using the AC susceptibility measurement, thecritical transition temperature T_c of samples is 91.5 K for the highest value, and the transitionwidth ΔT_c is less than 1 K. The highest magnetization critical current densities J_c achieved 10~6A/cm^2 under 5 T at 10 K and 1.35X10^4 A/cm^2 under 2 T at 70 K (H//c), respectively. The resultscombining the SEM observation indicate that doping of Y211 particles is more effective in improvingthe growth quality of melt-textured YBCO superconductor and in reducing the micro-cracks ofspecimens. Doping of Y_2O_3 powder forms the rod-shaped Y211 particles, but doping of Y211 particlesdirectly to matrix materials forms the spherical Y211 particles mainly. Combining themicrostructures with J_c measurements shows that the interfaces are most important on flux bundlepinning, in which the gradient of free energy is larger than that of other place between the Y211particles and the Y123 matrix materials.
基金supported by the National Research Foundation of Korea(NRF)grant funded by the Korean government(MIST)(Nos.2021R1A2C2010925,RS-2023-00240326,and RS-2023-00220471)Basic Science Research Program through the NRF of Korea funded by the Ministry of Education(Nos.NRF-2019R1F1A1055284 and NRF-2021R1I1A1A01043885).
文摘The high-entropy alloy(HEA)superconductor,Ta_(1/6)Nb_(2/6)Hf_(1/6)Zr_(1/6)Ti_(1/6)(Ta-Nb-Hf-Zr-Ti),is systematically studied to examine changes in superconducting critical properties,critical temperature(T_(c)),critical cur-rent density(J_(c)),and upper critical field(H_(c2)),concerning thermal treatment conditions.Annealing condi-tion affects Jc more significantly than T_(c)and H_(c2),with a large improvement of flux pinning force density(F_(p)).The Jc of bare sample is reduced to 10 A cm^(-2)at an applied magnetic field of approximately 1.5 T,whereas the sample annealed at 550℃for 12 h exhibits J_(c)>100 kA cm^(-2)up to around 4 T.Furthermore,the Vickers hardness(HVIT)of the Ta-Nb-Hf-Zr-Ti HEA superconductor notably increases from∼384 to 528 HVIT following a 24-h annealing at 500℃.These results demonstrate that thermal annealing is a powerful process to optimize both the superconducting and mechanical properties of high-entropy alloy superconductors.
基金supported by the National High Technology Research and Development Program ('863' Program) of China (Grant No. 2006AA03Z213)
文摘The critical current density Jc is one of the most important parameters of high temperature superconducting films in superconducting applications, such as superconducting filter and superconducting Josephson devices. This paper presents a new model to describe inhomogeneous current distribution throughout the thickness of superconducting films applying magnetic field by solving the differential equation derived from Maxwell equation and the second London equation. Using this model, it accurately calculates the inductive third-harmonic voltage when the film applying magnetic field with the inductive measurement for Jc. The theoretic curve is consistent with the experimental results about measuring superconducting film, especially when the third-harmonic voltage just exceeds zero. The Jc value of superconducting films determined by the inductive method is also compared with results raeasured by four-probe transport method. The agreements between inductive method and transport method are very good.
文摘A promising method —“powder in tube”technique was used to fabricate Ag-sheathed Bi-2223 superconductive tapes with high critical current density.After a combination processing of pressing and subsequent heat treatment,we obtained tapes with high degree of texture,good compaction and uniform properties.At 77 K in zero field,J_C was higher than 1×10~4 A/cm^2 while the highest J_C was 1.69×10~4 A/cm^2.SEM and XRD was used to detect the tapes texture,and the relationship be- tween J_C and the degree of texture is discussed.In addition,the reason for obstacling the improvement of J_C is also investigated.
基金the financial support from the Natural Science Foundation for Distinguished Young Scholars of Hunan Province(2020JJ2047)the science and technology innovation Program of Hunan Province(2022RC3048)+2 种基金the Program of Huxiang Young Talents(2019RS2002)the Innovation-Driven Project of Central South University(2020CX027)the Fundamental Research Funds for the Central Universities of Central South University(2021zzts0125)。
文摘Apparent critical current density(j_(Ac)^(a))of garnet all-solid-state lithium metal symmetric cells(ASSLSCs)is a fundamental parameter for designing all-solid-state lithium metal batteries.Nevertheless,how much the possible maximum apparent current density that a given ASSLSC system can endure and how to reveal this potential still require study.Herein,a capacity perturbation strategy aiming to better measure the possible maximum j_(Ac)^(a)is proposed for the first time.With garnet-based plane-surface structure ASSLSCs as an exemplification,the j_(Ac)^(a)is quite small when the capacity is dramatically large.Under a perturbed capacity of 0.001 mA h cm^(-2),the j_(Ac)^(a)is determined to be as high as 2.35 mA cm^(-2)at room temperature.This investigation demonstrates that the capacity perturbation strategy is a feasible strategy for measuring the possible maximum j_(Ac)^(a)of Li/solid electrolyte interface,and hopefully provides good references to explore the critical current density of other types of electrochemical systems.
基金NATO reintegration grant，TUBITAK research Foundation
文摘Temperature dependence of tbe pair-breaking critical current density of MgB2, jd（T）, is studied using a two-band Ginzburg-Landau theory. The results are shown to be in good agreement with experimental data for the superconducting magnesium diboride MgB2.
基金Project supported by the National Natural Science Foundation of China(Nos.12302278,U2241267,12172155,and 11932008)the Fundamental Research Funds for the Central Universities of China(No.lzujbky-2022-48)the Natural Science Foundation of Gansu Province of China(No.24JRRA473)。
文摘High-temperature superconducting(HTS)rare-earth Ba_(2)Cu_(3)O_(7-x)(REBCO)coated conductors(CCs)have significant potential in high-current and high-field applications.However,owing to the weak interface strength of the laminated composite REBCO CCs,the damage induced by the thermal mismatch stress under a combination of epoxy impregnation,cooling,and quenching can cause premature degradation of the critical current.In this study,a three-dimensional(3D)electromagnetic-thermal-mechanical model based on the H-formulation and cohesive zone model(CZM)is developed to study the critical current degradation characteristics in an epoxy-impregnated REBCO CC caused by the damage during a quench.The temperature variation,critical current degradation of the REBCO CC,and its degradation onset temperature calculated by the numerical model are in agreement with the experimental data taken from the literature.The delamination of the REBCO CC predicted by the numerical model is consistent with the experimental result.The numerical results also indicate that the shear stress is the main contributor to the damage propagation inside the REBCO CC.The premature degradation of the critical current during a quench is closely related to the interface shear strength inside the REBCO CC.Finally,the effects of the coefficient of thermal expansion(CTE)of the epoxy resin,thickness of the substrate,and substrate material on the critical current degradation characteristics of the epoxy-impregnated REBCO CC during a quench are also discussed.These results help us understand the relationship between the current-carrying degradation and damage in the HTS applications.
基金Supported by the National Natural Science Foundation of China under Grant No 11372096the Research Fund for the Doctoral Program of Higher Education of China
文摘The strain effect on the critical current is one of the most important properties for polycrystalline YBa2 Cu3O7-δ （REBCO, RE： rare earth） films, in which the reversible effect is intrinsic in the range of strain 0 and the irreversible strain εirr. By introducing the applied strain, a modified grain boundaries （GBs） in the REBCO film is developed. lattice model combining the strain and misorientation of A good agreement of the calculation on the lattice model with the experimental data shows that the lattice model is able to well describe the reversible effect of axial strain on the critical current of the REBCO film, and provides a good understanding of the mechanism of the reversible effect of the strain. Moreover, the effects of the crystallographic texture of the REBCO film and the residual strain εr on the variation of the critical current with the applied strain are extensively investigated. Furthermore by using the developed lattice model, the irreversible strain εirr of the REBCO film can be theoretically determined by comparing the calculation of the critical current-strain curve with the experimental data.
文摘The empirically reported values of the critical current density (j<sub>c</sub>) of Bi-2212 as 2.4 × 10<sup>5</sup> (j<sub>c</sub><sub>1</sub>;Sample 1) and 1.0 × 10<sup>6</sup> A/cm<sup>2</sup> (j<sub>c</sub><sub>2</sub>;Sample 2) are intriguing because both of them correspond to the same values of the temperature T = 4.2 K and the applied magnetic field H = 12 × 10<sup>4</sup> G. This difference is conventionally attributed to such factors—not all of which are quantifiable—as the geometry, dimensions and the nature of dopants and the manners of preparation of the samples which cause their granular structures, grain boundaries, alignment of the grains and so on to differ. Based on the premise that the chemical potential μ subsumes most of these features, given herein is a novel explanation of the said results in terms of the values of μ of the two samples. This paper revisits the problem that was originally addressed in [Malik G.P., Varma V.S. (2020) WJCMP, 10, 53-70] in the more accurate framework of a subsequent paper [Malik G.P., Varma V.S. (2021) JSNM, 34, 1551-1561]. Besides, it distinguishes between the contributions of the electro-electron (e-e) and the hole-hole (h-h) pairs to j<sub>c</sub>—a feature to which no heed was paid earlier. The essence of our findings is that the j<sub>c</sub>s of the two samples differ because they are characterized by different values of the primary variables μ<sub>i</sub><sub> </sub>and <img src="Edit_e1b831e9-dc51-4c3b-bd84-fa905e3e62b5.png" alt="" />, where <img src="Edit_1f775a80-30ab-447d-861f-afb4ba8fba6a.png" alt="" /> is the effective mass of a charge-carrier and m<sub>e</sub><sub> </sub>is the free-electron mass and i = 1 and 2 denote Sample 1 and Sample 2, respectively. In the scenario of the charge-carriers being predominantly h-h pairs, the values of these parameters are estimated to be: μ<sub>1</sub> ≈ 12.3 meV, η<sub>1</sub> ≈ 0.58;μ<sub>2</sub> ≈ 22.7 meV, η<sub>2</sub> ≈ 0.94. Following from these and similar estimates when the charge-carriers are e-e pairs, given below for each sample are the detailed results for the values of the secondary variables viz. the number density of the charge-carriers and their critical velocity, the number of occupied Landau levels and the magnetic interaction parameter.
基金Project supported by the National Key Research and Development Program of China(Grant No.2023YFF0720500)the State Key Program of the National Natural Science Foundation of China(Grant No.U22A2019)the National Key Project(Grant No.22-05-CXZX-04-03-15)。
文摘It is very important for high temperature superconducting electronic devices to increase the grain size of YBCO epitaxial films because it can effectively reduce the defects and improve the probability of successful preparation of Josephson junction.In this study,YBa_(2)Cu_(3)O_(7-δ)(YBCO)films with grain size in excess of 1.5μm were successfully prepared by the directly heating SrTiO_(3)substrates coated by Si C on their back.Interestingly,the grain size of YBCO film is enhanced greatly by this directly heating method,and the critical temperature TCand critical current density JCof YBCO films are as high as 91.5 K and 3.5 MA/cm^(2),respectively.Compared with the traditional indirect heating method,which involves applying silver paste and then using a heat soaking block(e.g.Inconel 600),this direct heating method effectively enhances the grain size of YBCO film and the possibility of successful preparation of Josephson junction.
基金supported by the National Key Research and Development Program of China(No.2021YFA0718800)the Natural Science Foundation of Sichuan Province(No.2023NSFSC0993)+1 种基金the National Natural Science Foundation of China(Nos.52021001,U22A20132 and 12074056)Sichuan Science and Technology Program(No.2021JDTD0010).
文摘The fabrication of high-quality YBa_(2)Cu_(3)O_(7)−δ(YBCO)nanowires has garnered significant attention in the field of high-temperature superconductivity due to their potential applications in quantum communication,deep space exploration,and various other fields.Cl_(2)-assisted reactive ion etching(RIE)stands out as a more effective and efficient method for patterning scalable thin films.However,neither RIE nor high-density RIE has achieved superconducting YBCO nanowires with a width smaller than 3μm.Here,we delve into the factors that limit the line width of Cl_(2)-assisted inductively coupled plasma reactive ion etching(ICP-RIE)processing and the method to elimiate them.Our approach involves utilizing Cl_(2)/Ar as etching gas and incorporating a specialized vacuum heating process after etching.Our experimental results demonstrate the successful realization of 10 nm-thick YBCO nanowires with widths as small as 0.15μm,exhibiting excellent performance in terms of their intrinsic superconducting properties.The mechanism is evidenced by X-ray photoelectron spectroscopy(XPS)analysis in comparison of nanowires with and without heating treatment,in which the residual Cl_(2) on the sidewall of nanowires evaporates and oxidizes Cu^(+)back into Cu^(2+)in an unetched state.
基金Project supported by the Innovation Program for Quantum Science and Technology(Grant No.2021ZD0302103)the National Natural Science Foundation of China(Grant Nos.62325505,62020106014,62175140,62475138,92165106,12104276)the Shanxi Province Graduate Student Research Innovation Project(Grant No.2024KY105)。
文摘The Josephson effect,an important quantum supercurrent phenomenon,has been extensively studied in superconductors and superfluids.In this paper,we investigate the rich physics of one-dimensional Josephson junctions in a red-detuned optical lattice with sodium(Na)quantum gas.A one-dimensional Josephson array is formed by setting up an optical lattice using a red-detuned laser.By characterizing the dependence of Josephson oscillations of the lattice depth,we experimentally demonstrate the Josephson current.The lattice depth is controlled by altering the lattice power,and our observations are consistent with theoretical predictions.These findings offer valuable insights into quantum coherent transport and the intricate dynamics inherent to superfluidity.
文摘Magnetic levitation of the fusion target by coating a thin MgB_(2)superconducting shell on its outer surface has recently been proposed in inertial confinement fusion(ICF)to realize a noncontact support of the target at~20 K to boost the implosion performance and fusion yield.To avoid possible effects on target ablation,the coated MgB_(2)shell is anticipated to be as thin as possible while fulfilling the target levitation requirements.Under this circumstance,the fabrication of an MgB_(2)shell with reduced thickness has been explored using a hybrid physical-chemical vapour deposition method.By gradually decreasing the deposition time,a set of MgB_(2)shells were grown on 1 mm diameter Si_(3)N_(4)spheres with the thickness reducing from 720 nm to 200 nm.The spherical shells all have a polycrystalline structure characterized by closely packed hexagonal grains,with both the grain size and thickness diminishing as the shell thickness decreases.The superconducting transition temperature Tcof the shells,as determined by both resistance and magnetization measurements,is in the range of 38-40 K and all shells exhibit ideal diamagnetism at low temperatures.For the thinnest shell of 200 nm,the superconducting critical current density Jcat 20 K reaches 8.0×10^(6)A/cm^(2)and 2.1×10^(5)A/cm^(2)under zero and 2 T applied field,respectively.The results indicate that it is experimentally feasible to fabricate MgB_(2)spherical shells with a thickness as low as 200 nm while maintaining the high Tcand Jc,thereby taking a further step towards the application of the shell in superconducting magnetic levitation for ICF.
基金supported by National Key R&D Program of China(No.2022YFB3804004)the Research Project of Ganjiang Innovation Academy,Chinese Academy of Sciences(E355E003).
文摘In this work,bulk-Nb_(3)Sn superconductors were prepared by the powder metallurgy route under the heat treatment conditions of rapid-heating and short-holding and the effect of Cu content and rapid-heating process on the microstructure and superconducting properties of bulk-Nb_(3)Sn superconductors were systematically investigated.The results showed that both of critical temperature(Tc)and critical current density(Jc)of bulk samples got decreased with increasing Cu content.The rapid-heating and short-holding process exhibited a'healing'effect on the holes in Nb_(3)Sn layers,significantly improving the compactness of the bulk samples.Moreover,the bulk sample,which was heat treated at 600℃for 50 h,then induction heated to 1000℃and isothermally held for 20 s,exhibited the highest Jc,non-Cu values of 2.38×10^(9)A/m^(2)(at 4.2 K&6 T).And this could be attributed to the small average grain size,high content of Nb_(3)Sn superconducting phase,and the Cu(Sn)artificial pinning centers in the Nb_(3)Sn layer.Besides,Nb_(3)Sn wire by internal-tin method was processed using the same heat treatment schedule to validate the effectiveness of the rapid-heating process.The critical current(Ic)of the wire sample,measured via V-I characteristic curve at 4.2 K&6 T,was determined to be 96 A,corresponding to a Jc,layer value of 4593 A/mm^(2).Moreover,a Jc,non-Cu model(J_(c,non-Cu)=4985·x^(3.5)+0.466[-10-30 exp(0.00348/y)+577y]^(0.5)+45·e-z/175)⎠concerning with the microstructural parameters(x:superconducting phase content,y:average Sn content in Nb_(3)Sn layer,and z:grain size of Nb_(3)Sn)was proposed,providing a semi-quantitative reference to describe the Jc,non-Cu of bulk-Nb_(3)Sn superconductors.Finally,it should be noted that the relevant conclusions in this work regarding the kinetics of rapid-heating and microstructural evolution of bulk samples may require adjustment or further validation when applied to the structure of wires.
文摘After discovering high temperature superconducting materials 20 years ago, the preparation of applicable HTS materials has been pursued along with HTS mechanism and characteristic study. At present, the focus on the applied HTS technology has been moving to the industrial preparations from the laboratory research stage, and the technology has been well verified for practical applications from small to large scales. The fabrication techniques of engineering HTS materials are being industrialized; and various HTS devices are also on the way towards practical applications. This paper provides a comprehensive summary on the applied high temperature superconductivity with regard to various applicable HTS materials, their preparation techniques and charac- terization, and applications in a wide range.
