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
Interfaces and surfaces of YBa_2Cu_3O_(7-x)(YBCO)-Ag have been studied by SEM-EDX and AES.No effect of Ag on 123 structure in X-ray diffraction pattern was observed for 0.4 mol Ag doped YBCO.AES analysis indicated tha...Interfaces and surfaces of YBa_2Cu_3O_(7-x)(YBCO)-Ag have been studied by SEM-EDX and AES.No effect of Ag on 123 structure in X-ray diffraction pattern was observed for 0.4 mol Ag doped YBCO.AES analysis indicated that Ag segregated on surface of YBCO and resulted in decrease of YBCO-metal lead resistance.In addition,solution and segregation of Ag as elemental state were often appeared on interfaces and surfaces of high temperature annealed YBCO,whether elemental Ag or compound Ag_2O and AgNO_3 adopted as doping material.展开更多
By means of X-ray diffraction investigations and electric resistivity measurements the tempera- ture dependence of phase structure and supercon- ductivity in YBa_2Cu_3O_(7_x) over the temperature range of 20℃-950℃ h...By means of X-ray diffraction investigations and electric resistivity measurements the tempera- ture dependence of phase structure and supercon- ductivity in YBa_2Cu_3O_(7_x) over the temperature range of 20℃-950℃ have been studied.The lattice parameters a,b and c as well as conductivity as a function of annealing temperatures can be roughly divided into three zones which are superconductive orthorhombic structure 1(a<b(?)c/3) at 20℃-500℃,normal conductive orthorhombic structure 2(a<b<c/3)from 550℃ to about 750℃ and semiconductive-like tetragonal structure (a=b<c/3)from about 800℃ to 950℃.However, the boundaries of the three zones is not much distinctive because there is a continuous transi- tion from the orthorhombic to tetragonal struc- ture.Furthermore,the processes of orthorhom- bic-tetragonal transition in the range of 350℃-950℃ are not only continuous but also reversible.The isothermal transition of orthorhombic 2 to orthorhombic 1 occurs at 350℃-500℃,while the maximum rate of transition and high T_c superconductivity can be obtained at about 460℃.This process of isothermal transition depends on the ordering of oxygen atoms or vacancies and the thermodynamic equilibrium to allow the oxygen diffusion.展开更多
It is significant for low-cost preparation of YBa2Cu3O7-δ（YBCO） coated conductors to make clear the mechanism of orientation, copper segregation, and nucleation density in BaF2-derived YBCO crystallization. In the ...It is significant for low-cost preparation of YBa2Cu3O7-δ（YBCO） coated conductors to make clear the mechanism of orientation, copper segregation, and nucleation density in BaF2-derived YBCO crystallization. In the present work,a distinct nucleation mechanism was proposed based on a transient liquid phase induced by the size effect as well as near-equilibrium assumption. With this scheme the nucleation of YBCO prepared by metal–organic deposition（MOD） or the physical vapor deposition BaF2 process was semi-quantitatively analyzed, revealing that the direct driving force for nucleation is YBCO supersaturation in the liquid phase. The theoretical analysis on the nucleation orientation portion is evidenced by the experimental result.展开更多
YBa2Cu3O7-x(YBCO) thin film has been epitaxially deposited on (1120) sapphire with Y2O3-stabilized ZrO2 (YSZ) buffer layer and shown a high critical current density Jc of 1. 6×106A/cm2 at 77 K in zero magnetic fi...YBa2Cu3O7-x(YBCO) thin film has been epitaxially deposited on (1120) sapphire with Y2O3-stabilized ZrO2 (YSZ) buffer layer and shown a high critical current density Jc of 1. 6×106A/cm2 at 77 K in zero magnetic field. The orientation relationship of the multilayer film superconductor has been determined. The(001) plane of the YBCO film is parallel to the(100) surface of the YSZ intermediate layer. YSZ buffer layer with(100) preferred orientation is about 20 nm thick and contains element Ba, due to out-diffusion of Ba from YBCO layer. The(100) preferred orientation of YSZ buffer permits the growth of high quality YBCO thin film. Y2BaCuO5 precipitates with small size distribute uniformly in the YBCO thin film and it is favourable to raise critical current density Jc.展开更多
The patterning technologies and process order of high Tc(86K) super-conducting film bolometers have been studied. After the deposition, a conventional lithographic process was used to pattern the films with aqueous so...The patterning technologies and process order of high Tc(86K) super-conducting film bolometers have been studied. After the deposition, a conventional lithographic process was used to pattern the films with aqueous solution of HCl, and then the films were transferred into a tube furnace for annealing to form superconducting film. It eliminates the degradation of patterning process. The bolometric responsivity of approximately 34. 32 V/W is measured, and the detectivity is greater than 1. 62× 108cm · Hz1/2 · W-1, the noise equivalent powers NEP is 2. 1×10-9W.展开更多
Y_(1-x)Ho_xBa_2Cu_3O_(7-δ)(0<x<1) sinsle crystal thin films oriented with the caxis perpendicular to the sur-face were grown by DC magnetron sputtering technique. Target was pieced together with half of YBa_2Cu...Y_(1-x)Ho_xBa_2Cu_3O_(7-δ)(0<x<1) sinsle crystal thin films oriented with the caxis perpendicular to the sur-face were grown by DC magnetron sputtering technique. Target was pieced together with half of YBa_2Cu_3O_(7-δ)(YBCO) and half of HoBa_2Cu_3O_(7-δ)(HBCO) superconducting materials. As the distance between HBCO targetmaterial and substrate is varied , the Ho content in material is changed respectively. When the content of Ho is0. 7 (atom ratio) , the T_c>83K.展开更多
Developing suitable anode materials for potassium-ion batteries(PIBs)remains a great challenge owing to the limited theoretical capacity of active materials and large radius of K+ion(1.38?).To solve these obstacles,by...Developing suitable anode materials for potassium-ion batteries(PIBs)remains a great challenge owing to the limited theoretical capacity of active materials and large radius of K+ion(1.38?).To solve these obstacles,by integrating the principles of multielectron transfer and rational porous crystal framework,we creatively propose the monoclinic Cu_(3)(OH)_(2)V_(2)O_(7)·2H_(2)O(CVO)as a novel anode for PIBs.Furthermore,inspired by the metastable nature of CVO under high temperature/pressure,we skillfully design a facile hydrothermal recrystallization strategy without the phase change and surfactants addition.Thus,for the first time,the porous composite of Cu_(3)(OH)_(2)V_(2)O_(7)·2H_(2)O nanobelts covered in situ by reduced graphene oxide(CVO NBs/r GO)was assembled,greatly improving the deficiencies of CVO.When used as a novel anode for PIBs,CVO NBs/r GO delivers large specific capacity(up to 551.4 m Ah g^(-1)at 50 m A g^(-1)),high-rate capability(215.3 m Ah g^(-1)at 2.5 A g^(-1))and super durability(203.6 m Ah g^(-1)at 500 m A g^(-1)even after 1000 cycles).The outstanding performance can be ascribed to the synergistic merits of desirable structural features of monoclinic CVO nanobelts and the highly conductive graphene 3D network,thus promoting the composite material stability and electrical/ionic conductivity.This work reveals a novel metal vanadate-based anode material for PIBs,would further motivate the subsequent batteries research on M_(3)(OH)_(2)V_(2)O_(7)-n H_(2)O(M;Co,Ni,Cu,Zn),and ultimately expands valuable fundamental understanding on designing other high-performance electrode materials,including the combined strategies of multielectron transfer with rational porous crystal framework,and the composite fabrication of 1D electrode nanostructure with conductive carbon matrix.展开更多
Thin films of superconductors HoBa_2Cu_3O_(7-δ)(HBCO) were prepared by DC-sputtering technique. The epi-taxial growth was controlled by the ratio of the oxygen pressure and Ar pressure (O_2/Ar) , the subetrate temper...Thin films of superconductors HoBa_2Cu_3O_(7-δ)(HBCO) were prepared by DC-sputtering technique. The epi-taxial growth was controlled by the ratio of the oxygen pressure and Ar pressure (O_2/Ar) , the subetrate temperature T_s and the distance of the target to subetrate. Thin films deposited under the optimum conditions (Po_2/P_(Ar)= 1:2 ; T_s=730℃) show a critical temlierature clase to 87K and a transition width less than 1K. X-raydiffraction analysis shows that the films are highiy c-axis oriented. Auger electron spectroscopy depth profilingdemonstrates Ho diffusion into the Zr(Y)O_2 subetrate owing to the Ho subetitution for Y.展开更多
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.
文摘Interfaces and surfaces of YBa_2Cu_3O_(7-x)(YBCO)-Ag have been studied by SEM-EDX and AES.No effect of Ag on 123 structure in X-ray diffraction pattern was observed for 0.4 mol Ag doped YBCO.AES analysis indicated that Ag segregated on surface of YBCO and resulted in decrease of YBCO-metal lead resistance.In addition,solution and segregation of Ag as elemental state were often appeared on interfaces and surfaces of high temperature annealed YBCO,whether elemental Ag or compound Ag_2O and AgNO_3 adopted as doping material.
文摘By means of X-ray diffraction investigations and electric resistivity measurements the tempera- ture dependence of phase structure and supercon- ductivity in YBa_2Cu_3O_(7_x) over the temperature range of 20℃-950℃ have been studied.The lattice parameters a,b and c as well as conductivity as a function of annealing temperatures can be roughly divided into three zones which are superconductive orthorhombic structure 1(a<b(?)c/3) at 20℃-500℃,normal conductive orthorhombic structure 2(a<b<c/3)from 550℃ to about 750℃ and semiconductive-like tetragonal structure (a=b<c/3)from about 800℃ to 950℃.However, the boundaries of the three zones is not much distinctive because there is a continuous transi- tion from the orthorhombic to tetragonal struc- ture.Furthermore,the processes of orthorhom- bic-tetragonal transition in the range of 350℃-950℃ are not only continuous but also reversible.The isothermal transition of orthorhombic 2 to orthorhombic 1 occurs at 350℃-500℃,while the maximum rate of transition and high T_c superconductivity can be obtained at about 460℃.This process of isothermal transition depends on the ordering of oxygen atoms or vacancies and the thermodynamic equilibrium to allow the oxygen diffusion.
基金Project supported by the Science and Technology Commission of Shanghai Municipality,China(Grant Nos.13111102300 and 11dz1100302)the National Natural Science Foundation of China(Grant Nos.11174193 and 51202141)+1 种基金the National Basic Research Program of China(Grant Nos.2011CBA00105)the Science and Technology Commission of Shanghai Municipality,China(Grant No.14DZ2260700)
文摘It is significant for low-cost preparation of YBa2Cu3O7-δ（YBCO） coated conductors to make clear the mechanism of orientation, copper segregation, and nucleation density in BaF2-derived YBCO crystallization. In the present work,a distinct nucleation mechanism was proposed based on a transient liquid phase induced by the size effect as well as near-equilibrium assumption. With this scheme the nucleation of YBCO prepared by metal–organic deposition（MOD） or the physical vapor deposition BaF2 process was semi-quantitatively analyzed, revealing that the direct driving force for nucleation is YBCO supersaturation in the liquid phase. The theoretical analysis on the nucleation orientation portion is evidenced by the experimental result.
文摘YBa2Cu3O7-x(YBCO) thin film has been epitaxially deposited on (1120) sapphire with Y2O3-stabilized ZrO2 (YSZ) buffer layer and shown a high critical current density Jc of 1. 6×106A/cm2 at 77 K in zero magnetic field. The orientation relationship of the multilayer film superconductor has been determined. The(001) plane of the YBCO film is parallel to the(100) surface of the YSZ intermediate layer. YSZ buffer layer with(100) preferred orientation is about 20 nm thick and contains element Ba, due to out-diffusion of Ba from YBCO layer. The(100) preferred orientation of YSZ buffer permits the growth of high quality YBCO thin film. Y2BaCuO5 precipitates with small size distribute uniformly in the YBCO thin film and it is favourable to raise critical current density Jc.
文摘The patterning technologies and process order of high Tc(86K) super-conducting film bolometers have been studied. After the deposition, a conventional lithographic process was used to pattern the films with aqueous solution of HCl, and then the films were transferred into a tube furnace for annealing to form superconducting film. It eliminates the degradation of patterning process. The bolometric responsivity of approximately 34. 32 V/W is measured, and the detectivity is greater than 1. 62× 108cm · Hz1/2 · W-1, the noise equivalent powers NEP is 2. 1×10-9W.
文摘Y_(1-x)Ho_xBa_2Cu_3O_(7-δ)(0<x<1) sinsle crystal thin films oriented with the caxis perpendicular to the sur-face were grown by DC magnetron sputtering technique. Target was pieced together with half of YBa_2Cu_3O_(7-δ)(YBCO) and half of HoBa_2Cu_3O_(7-δ)(HBCO) superconducting materials. As the distance between HBCO targetmaterial and substrate is varied , the Ho content in material is changed respectively. When the content of Ho is0. 7 (atom ratio) , the T_c>83K.
基金supported by the National Natural Science Foundation of China(52072118,51772089)the Youth 1000 Talent Program of China+3 种基金the Research and Development Plan of Key Areas in Hunan Province(2019GK2235)the Key Research and Development Program of Ningxia(2020BDE03007)the China Postdoctoral Science Foundation(2019M653649)the Guangdong Basic and Applied Basic Research Fund(2019A1515110518,2019A1515111188,2020B0909030004)。
文摘Developing suitable anode materials for potassium-ion batteries(PIBs)remains a great challenge owing to the limited theoretical capacity of active materials and large radius of K+ion(1.38?).To solve these obstacles,by integrating the principles of multielectron transfer and rational porous crystal framework,we creatively propose the monoclinic Cu_(3)(OH)_(2)V_(2)O_(7)·2H_(2)O(CVO)as a novel anode for PIBs.Furthermore,inspired by the metastable nature of CVO under high temperature/pressure,we skillfully design a facile hydrothermal recrystallization strategy without the phase change and surfactants addition.Thus,for the first time,the porous composite of Cu_(3)(OH)_(2)V_(2)O_(7)·2H_(2)O nanobelts covered in situ by reduced graphene oxide(CVO NBs/r GO)was assembled,greatly improving the deficiencies of CVO.When used as a novel anode for PIBs,CVO NBs/r GO delivers large specific capacity(up to 551.4 m Ah g^(-1)at 50 m A g^(-1)),high-rate capability(215.3 m Ah g^(-1)at 2.5 A g^(-1))and super durability(203.6 m Ah g^(-1)at 500 m A g^(-1)even after 1000 cycles).The outstanding performance can be ascribed to the synergistic merits of desirable structural features of monoclinic CVO nanobelts and the highly conductive graphene 3D network,thus promoting the composite material stability and electrical/ionic conductivity.This work reveals a novel metal vanadate-based anode material for PIBs,would further motivate the subsequent batteries research on M_(3)(OH)_(2)V_(2)O_(7)-n H_(2)O(M;Co,Ni,Cu,Zn),and ultimately expands valuable fundamental understanding on designing other high-performance electrode materials,including the combined strategies of multielectron transfer with rational porous crystal framework,and the composite fabrication of 1D electrode nanostructure with conductive carbon matrix.
文摘Thin films of superconductors HoBa_2Cu_3O_(7-δ)(HBCO) were prepared by DC-sputtering technique. The epi-taxial growth was controlled by the ratio of the oxygen pressure and Ar pressure (O_2/Ar) , the subetrate temperature T_s and the distance of the target to subetrate. Thin films deposited under the optimum conditions (Po_2/P_(Ar)= 1:2 ; T_s=730℃) show a critical temlierature clase to 87K and a transition width less than 1K. X-raydiffraction analysis shows that the films are highiy c-axis oriented. Auger electron spectroscopy depth profilingdemonstrates Ho diffusion into the Zr(Y)O_2 subetrate owing to the Ho subetitution for Y.
