The Experts below are selected from a list of 306519 Experts worldwide ranked by ideXlab platform
Enge Wang - One of the best experts on this subject based on the ideXlab platform.
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anisotropic lithium insertion behavior in silicon nanowires binding energy diffusion barrier and Strain Effect
Journal of Physical Chemistry C, 2011Co-Authors: Qianfan Zhang, Yi Cui, Enge WangAbstract:Silicon nanowires (SiNWs) have recently been shown to be promising as high capacity lithium battery anodes. SiNWs can be grown with their long axis along several different crystallographic directions. Due to distinct atomic configuration and electronic structure of SiNWs with different axial orientations, their lithium insertion behavior could be different. This paper focuses on the characteristics of single Li defects, including binding energy, diffusion barriers, and dependence on uniaxial Strain in [110], [100], [111], and [112] SiNWs. Our systematic ab initio study suggests that the Si–Li interaction is weaker when the Si–Li bond direction is aligned close to the SiNW long axis. This results in the [110] and [111] SiNWs having the highest and lowest Li binding energy, respectively, and it makes the diffusion barrier along the SiNW axis lower than other pathways. Under external Strain, it was found that [110] and [001] SiNWs are the most and least sensitive, respectively. For diffusion along the axial ...
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anisotropic lithium insertion behavior in silicon nanowires binding energy diffusion barrier and Strain Effect
Journal of Physical Chemistry C, 2011Co-Authors: Qianfan Zhang, Yi Cui, Enge WangAbstract:Silicon nanowires (SiNWs) have recently been shown to be promising as high capacity lithium battery anodes. SiNWs can be grown with their long axis along several different crystallographicdirections.Duetodistinctatomicconfiguration and electronic structure of SiNWs with different axial orienta- tions, their lithium insertion behavior could be different. This paper focuses on the characteristics of single Li defects, includ- ing binding energy, diffusion barriers, and dependence on uniaxial Strain in (110), (100), (111), and (112) SiNWs. Our systematic ab initio study suggests that the SiLi interaction is weaker when the SiLi bond direction is aligned close to the SiNW long axis. This results in the (110) and (111) SiNWs having the highest and lowest Li binding energy, respectively, and it makes the diffusionbarrieralongtheSiNWaxislowerthanotherpathways.UnderexternalStrain,itwasfoundthat(110)and(001)SiNWsare the most and least sensitive, respectively. For diffusion along the axial direction, the barrier increases (decreases) under tension (compression). This feature results in a considerable difference in the magnitude of the energy barrier along different diffusion pathways.
Marlon J Dedicatoria - One of the best experts on this subject based on the ideXlab platform.
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intrinsic Strain Effect on critical current in cu stabilized gdbco coated conductor tapes with different substrates
Superconductor Science and Technology, 2013Co-Authors: Hyung-seop Shin, Marlon J DedicatoriaAbstract:The intrinsic Strain Effect on critical current, Ic in Cu-stabilized GdBCO coated conductor (CC) tapes under bending and uniaxial tension has been investigated. The bending deformation tolerance of Ic in GdBCO CC tapes, fabricated by reactive co-evaporation by deposition and reaction (RCE-DR) with substrate materials of Hastelloy and stainless steel and fabricated by the metal organic chemical vapour deposition (MOCVD) process was evaluated. The intrinsic Strain response of Ic under bending was found to be independent of the fabrication process, the substrate material and the geometry of the sample. For samples with a Hastelloy substrate, the intrinsic Strain response of Ic/Icmax under bending was well correlated with those under uniaxial tension. However, for samples with a stainless steel substrate, these had a large Strain sensitivity for Ic under uniaxial tension even though this showed a much higher irreversible Strain limit up to 1.05%.
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variation of the Strain Effect on the critical current due to external lamination in rebco coated conductors
Superconductor Science and Technology, 2012Co-Authors: Hyung-seop Shin, Marlon J DedicatoriaAbstract:The Effect of additional brass laminate on the Strain tolerance of the critical current, Ic, in Cu-stabilized REBCO (RE standing for rare earth) coated conductor (CC) tapes was evaluated. The degradation behaviours of Ic under uniaxial tension at self-field and under a magnetic field, using a pair of permanent magnets, in REBCO CC tapes with different architectures, namely Cu-stabilized and externally laminated samples, have been investigated. The Strain dependence of Ic in differently processed samples of SmBCO and YBCO CC tapes under uniaxial tension testing was measured at 0 T (self-field), 0.2 T, 0.3 T, and 0.5 T. The measured Ic/Ic0–eten relation for Cu-stabilized and externally laminated REBCO samples under a magnetic field showed that additional brass laminate enhances the irreversible Strain limits from 0.5% to about 0.85% in REBCO CC tapes. The variation in the Strain Effect on Ic in brass laminated samples becomes minimal under a magnetic field in the range of 0–0.5 T for all REBCO CC tapes tested.
Najib Cheggour - One of the best experts on this subject based on the ideXlab platform.
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reversible Effect of Strain on transport critical current in bi2sr2cacu2o8 x superconducting wires a modified descriptive Strain model
Superconductor Science and Technology, 2012Co-Authors: Najib Cheggour, T G Holesinger, Theodore C Stauffer, J Jiang, Loren F GoodrichAbstract:A reversible Strain Effect on transport critical current Ic was found in Bi2Sr2CaCu2O8 + x (Bi-2212) high-temperature superconducting round wires. Ic showed unambiguous reversibility at 4 K and 16 T up to an irreversible Strain limit of about 0.3 % in longitudinal tension, prompting hope that the Bi-2212 conductor has the potential to sustain mechanical Strains generated in high-field magnets. However, Ic was not reversible under longitudinal compression and buckling of Bi-2212 grain colonies was identified as the main reason. A two-component model was proposed, which suggests the presence of mechanically weak and strong Bi-2212 components within the wire filaments. Porosity embedded in the weak component renders it structurally unsupported and, therefore, makes it prone to cracking under Strain e. Ic(e) is irreversible in tension if the weak component contributes to the transport critical current but becomes reversible once connectivity of the weak component is broken through Strain increase or cycling. A modified descriptive Strain model was also developed, which illustrates the Effect of Strain in the Bi-2212 conductor and supersedes the existing descriptive model. Unlike the latter, the new model suggests that higher pre-compressive Strains should improve Ic if buckling of Bi-2212 grains does not occur, and should result in a wider Ic(e) plateau in the applied tensile regime without degradation of the initial Ic. The new model postulates that a reversible Strain Effect should exist even in the applied compressive Strain regime if buckling of Bi-2212 grains could be prevented through elimination of porosity and mechanical reinforcement of the wire.
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Reversible axial-Strain Effect in Y-Ba-Cu-O coated conductors*
Superconductor Science and Technology, 2005Co-Authors: Najib Cheggour, John W. Ekin, Cornelis Leo Hans Thieme, Y Y. Xie, Venkat Selvamanickam, Ron FeenstraAbstract:The recently discovered reversible Strain Effect in Y?Ba?Cu?O (YBCO) coated conductors contrasts with the general understanding that the Effect of Strain on the critical-current density Jc in practical high-temperature superconductors is determined only by crack formation in the ceramic component. Instead of having a constant Jc as a function of Strain before an irreversible drop when cracks form in the superconductor, Jc in YBCO coated conductors can decrease or increase reversibly with Strain over a significant Strain range up to an irreversible Strain limit. This reversible Effect is present in samples fabricated either with rolling-assisted biaxially textured Ni?W substrates or with ion-beam-assisted deposition on Hastalloy substrates. The reversibility of Jc with Strain is observed for thin as well as thick YBCO films, and at two very different temperatures (76 and 4?K). The reversible Effect is dependent on temperature and magnetic field, thus indicating its intrinsic nature. We also report an enhancement of the irreversible Strain limit ?irr where the reversible Strain Effect ends and YBCO cracking starts. The value of ?irr increases from about 0.4% to more than 0.5% when YBCO coated conductors are fabricated with an additional Cu protection layer.
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magnetic field dependence of the reversible axial Strain Effect in y ba cu o coated conductors
IEEE Transactions on Applied Superconductivity, 2005Co-Authors: Najib Cheggour, John W. Ekin, C L H ThiemeAbstract:The critical-current density J/sub c/ of an yttrium-barium-copper-oxide (YBCO) coated conductor deposited on a biaxially-textured Ni-5at.%W substrate was measured at 76.5 K as a function of axial tensile Strain /spl epsiv/ and magnetic field B applied parallel to the YBCO (a,b) plane. Reversibility of J/sub c/ with Strain was observed up to /spl epsiv//spl sime/0.6% over the entire field range studied (from 0.05 to 16.5 T), which confirms the existence of an intrinsic Strain Effect in YBCO coated conductors. J/sub c/ vs. /spl epsiv/ depends strongly on magnetic field. The decrease of J/sub c/(/spl epsiv/) grows systematically with magnetic field above 2-3 T, and, unexpectedly, the reverse happens below 2 T as this decrease shrinks with increasing field. The pinning force density F/sub p/=J/sub c//spl times/B scaled with field for all values of Strain applied, which shows that F/sub p/ can be written as K(T,/spl epsiv/)b/sup p/(1-b)/sup q/, where p and q are constants, K is a function of temperature and Strain, b=B/B/sub c2//sup */ is the reduced magnetic field, and B/sub c2//sup */ is the Effective upper critical field at which F/sub p/(B) extrapolates to zero.
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reversible axial Strain Effect and extended Strain limits in y ba cu o coatings on deformation textured substrates
Applied Physics Letters, 2003Co-Authors: Najib Cheggour, John W. Ekin, C C Clickner, D T Verebelyi, C L H Thieme, R Feenstra, A GoyalAbstract:The dependence of transport critical-current density Jc on axial tensile Strain e was measured at 76 K and self-magnetic field for YBa2Cu3O7−δ (YBCO) coatings on buffered, deformation-textured substrates of pure Ni, Ni–5-at. %-W, and Ni–10-at. %-Cr–2-at. %-W. Expectations have been that the Strain tolerance of these composites would be limited by the relatively low yield Strains of the deformation-textured substrates, typically less than 0.2%. However, results show that the irreversible degradation of Jc(e) occurs at a Strain equal to about twice the yield Strain of the substrate. Therefore, YBCO/Ni-alloy composites may satisfy axial-Strain performance requirements for electric devices, including the most demanding applications, motors and generators in which a Strain tolerance exceeding 0.25% is needed. Furthermore, the YBCO/Ni–5-at. %-W conductors showed a reversible Strain Effect, which may be induced by a reversible Strain-field broadening around mismatch dislocations at the grain boundaries. This eff...
Hyung-seop Shin - One of the best experts on this subject based on the ideXlab platform.
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intrinsic Strain Effect on critical current in cu stabilized gdbco coated conductor tapes with different substrates
Superconductor Science and Technology, 2013Co-Authors: Hyung-seop Shin, Marlon J DedicatoriaAbstract:The intrinsic Strain Effect on critical current, Ic in Cu-stabilized GdBCO coated conductor (CC) tapes under bending and uniaxial tension has been investigated. The bending deformation tolerance of Ic in GdBCO CC tapes, fabricated by reactive co-evaporation by deposition and reaction (RCE-DR) with substrate materials of Hastelloy and stainless steel and fabricated by the metal organic chemical vapour deposition (MOCVD) process was evaluated. The intrinsic Strain response of Ic under bending was found to be independent of the fabrication process, the substrate material and the geometry of the sample. For samples with a Hastelloy substrate, the intrinsic Strain response of Ic/Icmax under bending was well correlated with those under uniaxial tension. However, for samples with a stainless steel substrate, these had a large Strain sensitivity for Ic under uniaxial tension even though this showed a much higher irreversible Strain limit up to 1.05%.
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variation of the Strain Effect on the critical current due to external lamination in rebco coated conductors
Superconductor Science and Technology, 2012Co-Authors: Hyung-seop Shin, Marlon J DedicatoriaAbstract:The Effect of additional brass laminate on the Strain tolerance of the critical current, Ic, in Cu-stabilized REBCO (RE standing for rare earth) coated conductor (CC) tapes was evaluated. The degradation behaviours of Ic under uniaxial tension at self-field and under a magnetic field, using a pair of permanent magnets, in REBCO CC tapes with different architectures, namely Cu-stabilized and externally laminated samples, have been investigated. The Strain dependence of Ic in differently processed samples of SmBCO and YBCO CC tapes under uniaxial tension testing was measured at 0 T (self-field), 0.2 T, 0.3 T, and 0.5 T. The measured Ic/Ic0–eten relation for Cu-stabilized and externally laminated REBCO samples under a magnetic field showed that additional brass laminate enhances the irreversible Strain limits from 0.5% to about 0.85% in REBCO CC tapes. The variation in the Strain Effect on Ic in brass laminated samples becomes minimal under a magnetic field in the range of 0–0.5 T for all REBCO CC tapes tested.
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the Strain Effect on critical current in ybco coated conductors with different stabilizing layers
Superconductor Science and Technology, 2005Co-Authors: Hyung-seop Shin, Kihyun Kim, John Ryan C Dizon, Taeyoung KimAbstract:The tensile Strain dependences of the critical current (Ic) in YBa2Cu3O7−δ (YBCO) coated conductors fabricated by using the rolling-assisted biaxially textured Ni–W substrates (RABiTS)–pulsed laser deposition (PLD) method were examined at 77 K and in self magnetic field. Cu and stainless steel layers were used as stabilizers to the YBCO coated conductor, and the Effects of stabilizing layers on the Strain tolerance of Ic were investigated, compared with the case without a stabilizing layer. The lamination of stabilizer produced an increase in the yield strength and Strain tolerance of Ic in coated conductors. All YBCO coated conductors tested showed a reversible Strain Effect and a peak in the relation between Ic and applied Strain. The peak Strain of Ic and the irreversible Strains for Ic degradation were enhanced when the YBCO coated conductor was laminated with a stabilizing layer. For the case laminated with a stainless steel layer, Ic recovered reversibly until the applied Strain reached to about 0.5% and showed its peak at a Strain of 0.42%, comparing to the case without a stabilizing layer, which were 0.21% and 0.18%, respectively. It can be predicted that the lamination of a stabilizing layer produced a significant residual compressive Strain to the YBCO film during cooling to 77 K, which influenced the axial Strain tolerance of YBCO coated conductors. Therefore, the Ic–tensile Strain relation in YBCO coated conductors could be explained by a two-stage deformation; stage I is the region where YBCO film behaves elastically and Ic recovers when the stress is released. Stage II is the region where Ic decreases irreversibly attributable to the cracking induced in the YBCO film due to the significant plastic deformation of the substrate or the stabilizing layer.
Shigeo Nagaya - One of the best experts on this subject based on the ideXlab platform.
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the reversible Strain Effect on critical current over a wide range of temperatures and magnetic fields for ybco coated conductors
Superconductor Science and Technology, 2010Co-Authors: M Sugano, K. Shikimachi, Naoki Hirano, Shigeo NagayaAbstract:The Strain Effect on critical current (Ic(?)) in Y Ba2Cu3O7 ? ? (YBCO) coated conductors was evaluated at temperatures in the range 20?83?K under magnetic fields parallel to the c-axis up to 10?T. The peaked reversible variation of Ic with applied uniaxial Strain was confirmed in the self-field at all tested temperatures. The Strain sensitivity increases with increasing temperature, resulting in a more pronounced reversible suppression with Strain at higher temperature. Interestingly, it was found that the peak Strain corresponding to the maximum of Ic shifts to the compressive side with decreasing temperature. Such a peak shift cannot be explained by a change in the thermal residual Strain of the YBCO film, suggesting that the peak Strain of the Ic(?) in YBCO coated conductors is not determined only by relaxation of the residual Strain. The Strain sensitivity of Ic(?) at 60?K becomes greater with increasing magnetic field, while the influence of the magnetic field is much less pronounced at 20?K. The in-field Ic(?), including the compressive Strain region as well as the tensile region, shows a double peak behavior at low magnetic field at 77 and 83?K. The temperature and magnetic field Effect on Ic(?) in YBCO coated conductors is discussed considering flux pinning within the grains and on grain boundaries.
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reversible Strain limit of critical currents and universality of intrinsic Strain Effect for rebco coated conductors
Superconductor Science and Technology, 2009Co-Authors: Kozo Osamura, Shigeo Nagaya, M Sugano, Kohichi Nakao, Yuh Shiohara, A Ibi, Yutaka Yamada, Naoji Nakashima, Takashi Saitoh, Yasuhiro IijimaAbstract:Intensive research work has been carried out in order to develop industrially available HTS REBCO-coated conductors under the NEDO project in Japan. Recently, several groups in the project succeeded in the development of high performance coated conductors. Their characteristic features have been evaluated in terms of mechanical properties and their influence on critical currents. The mechanical properties at RT and 77 K were analyzed on the basis of the rule of mixtures. The force-free Strain (Aff) was analytically deduced, which indicates the Strain at which the residual stress exerted on the superconducting layer becomes zero. Tensile Strain dependence on critical currents could be divided into elastic and brittle regions. The reversible Strain limit (Arev) was defined as a Strain at which the critical current recovers elastically to the level of 99% Ico. Within the elastic region, the critical current showed a convex Strain dependence, which is explained as Ekin's intrinsic Strain Effect. The degradation beyond the reversible Strain limit was attributed to a fracture of the superconducting layer. As a whole, the present study made clear quantitatively the tensile Strain behavior of critical currents and proposed a reasonable definition for the reversible Strain limit.
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Simultaneously bending and tensile Strain Effect on critical current in YBCO coated conductors
Physica C-superconductivity and Its Applications, 2007Co-Authors: Michinaka Sugano, K. Shikimachi, Naoki Hirano, Shigeo NagayaAbstract:YBCO coated conductors have been expected for the application to a coil for superconducting magnetic energy storage (SMES). In the application to a superconducting coil, the coated conductors experience bending, uniaxial tensile Strain and their combined Strain. Therefore, the influence of simultaneous bending and tensile Strain on critical current should be revealed. In this work, we developed the test method of critical current under such combined Strain state. As a result, it was confirmed that compressive pre-bending can improve the stress tolerance of the YBCO coated conductors. On the other hand, compressive bending Strain suppresses the initial critical current by the intrinsic Strain Effect. These results indicate that optimal bending radius should be selected in order to realize superior stress tolerance and high current capacity simultaneously.
