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
The structural characteristics of different alkoxides of Y. Ba and Cu are studied with quantum chemi-cal CNDO /2 calculations. The relative hydrolysis rate coefficients k_M of them are obtained according tothe relati...The structural characteristics of different alkoxides of Y. Ba and Cu are studied with quantum chemi-cal CNDO /2 calculations. The relative hydrolysis rate coefficients k_M of them are obtained according tothe relationship between frontier orbitals and organic chemical reactions. Based on the above results. properexperimental conditions for the preparation of homogeneous ultra-purity. submicro high-T_cYBa_2Cu_3O_(7-δ) superconducting powders are proposed.展开更多
This paper reports the experimental results of the investigation on elemental substitution effects in YBa_2Cu_3O_(7-δ) and the new physical ideas deduced comprehensively. It is shown that all the orthorhombic crystal...This paper reports the experimental results of the investigation on elemental substitution effects in YBa_2Cu_3O_(7-δ) and the new physical ideas deduced comprehensively. It is shown that all the orthorhombic crystalline structure, oxygen content, oxidation valence of Cu atoms, and metal-semiconductor (insulator) transition are only the extrinsic factors deter mining the T_c of the systems, and there are two mechanisms of substitution effects, namely the mechanism of the substitution effects outside the CuO_2 planes and that within the CuO_2 planes. We suggest that the mobile carrier concentration and the dynamic, short-range antiferromagnetic correlation between Cu(2) atoms on the CuO_2 planes are the two intrinsic factors determining the high T_c superconductivity.展开更多
LaMnO_(3)(LMO) cap layers with different surface roughness were prepared on epi-MgO/ion-beam-assisted deposition (IBAD) MgO/solution deposition planarized (SDP) Y<sub>2</sub>O<sub>3</sub>/Haste...LaMnO_(3)(LMO) cap layers with different surface roughness were prepared on epi-MgO/ion-beam-assisted deposition (IBAD) MgO/solution deposition planarized (SDP) Y<sub>2</sub>O<sub>3</sub>/Hastelloy tape. The effects of the surface roughness of LMO on the crystallization, texture and superconducting properties of Yba<sub>2</sub>Cu<sub>3</sub>O<sub>7?δ </sub> (YBCO) films were systematically investigated. The crystallization and epitaxial texture of resulting YBCO film are significantly improved with the surface roughness of LMO decreasing from 7.0 to 1.3nm. High-performance YBCO-coated conductors could be achieved if surface roughness of LMO cap layer is well controlled.展开更多
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The structural characteristics of different alkoxides of Y. Ba and Cu are studied with quantum chemi-cal CNDO /2 calculations. The relative hydrolysis rate coefficients k_M of them are obtained according tothe relationship between frontier orbitals and organic chemical reactions. Based on the above results. properexperimental conditions for the preparation of homogeneous ultra-purity. submicro high-T_cYBa_2Cu_3O_(7-δ) superconducting powders are proposed.
基金Project supported by the Combined Centre of Research and Development of Superconduction Technology and the National Natural Science Foundation of China.
文摘This paper reports the experimental results of the investigation on elemental substitution effects in YBa_2Cu_3O_(7-δ) and the new physical ideas deduced comprehensively. It is shown that all the orthorhombic crystalline structure, oxygen content, oxidation valence of Cu atoms, and metal-semiconductor (insulator) transition are only the extrinsic factors deter mining the T_c of the systems, and there are two mechanisms of substitution effects, namely the mechanism of the substitution effects outside the CuO_2 planes and that within the CuO_2 planes. We suggest that the mobile carrier concentration and the dynamic, short-range antiferromagnetic correlation between Cu(2) atoms on the CuO_2 planes are the two intrinsic factors determining the high T_c superconductivity.
基金financially supported by the National Science Foundation of China(No.91421110)the National High Technology Research and Development Program of China(No.2014AA032702)+2 种基金the National Basic Research Program of China(No.2015CB358600)Sichuan Youth Science and Technology Innovation Research Team Fund(No.2011JTD0006)Sichuan Provincial Fund for Distinguished Young Academic and Technology Leaders(No.2014JQ0011)
文摘LaMnO_(3)(LMO) cap layers with different surface roughness were prepared on epi-MgO/ion-beam-assisted deposition (IBAD) MgO/solution deposition planarized (SDP) Y<sub>2</sub>O<sub>3</sub>/Hastelloy tape. The effects of the surface roughness of LMO on the crystallization, texture and superconducting properties of Yba<sub>2</sub>Cu<sub>3</sub>O<sub>7?δ </sub> (YBCO) films were systematically investigated. The crystallization and epitaxial texture of resulting YBCO film are significantly improved with the surface roughness of LMO decreasing from 7.0 to 1.3nm. High-performance YBCO-coated conductors could be achieved if surface roughness of LMO cap layer is well controlled.
