Application of a near coincidence site lattice theory to the orientations of YBa2Cu3O7−<i>x</i> grains on (001) MgO substrates

Hwang, D. M.; Ravi, T. S.; Ramesh, R.; Chan, Siu‐Wai; Chen, C. Y.; Nazar, L.; Wu, Xin; Inam, A.; Venkatesan, T.

doi:10.1063/1.104138

Cited by 150 publications

(30 citation statements)

References 14 publications

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“…Earlier, it was reported that the values of d~ in bicrystal-thin-films of YBa2CuaOT_, increase with a decrease in the misorientation angle of the grain boundary [1,2]. However, it was demonstrated later that some large-angle grain boundaries in bicrystals and in thin films transport high currents [3][4][5]. Since very many of the important future applications of the bulk materials inevitably in-*Present address: REM Electron Power Inc., 221 West Industry Court, Deer Park, NY 11729. volve polycrystals, it seems imperative to have an understanding of the structural features of grain boundaries that determine their properties.…”

Section: Introductionmentioning

confidence: 99%

Grain boundary chemistry and grain boundary dislocations in bulk YBa2Cu3O7-?

1994

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We report the results of our microchemical analyses of low-Z large-angle grain boundaries in bulk YBa2Cu307-~ using nanoprobe energy-dispersive-X-ray spectroscopy (EDX) and electronenergy-loss spectroscopy (EELS). We observed periodic variation in the concentration of Cu along the boundaries, and oxygen depletion at the boundaries. We found that the chemistry of the grain boundary is very sensitive to grain boundary dislocations (GBDs), while, in turn, the configuration of the GBDs is very sensitive to the boundary misorientation and the boundary plane normal. The strain field associated with closely spaced GBDs reduced the density of mobile holes at the boundary, which is expected to be detrimental to the superconducting properties of the boundary. The possible structural transition of the grain boundaries from an oxygen-deficient state to a fully oxygenated state near a coincidence orientation is discussed, based on the reduction of the elastic strain energy of the boundaries.

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Section: Introductionmentioning

confidence: 99%

Grain boundary chemistry and grain boundary dislocations in bulk YBa2Cu3O7-?

1994

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“…This is mostly due to the lower deposition temperature involved in the nucleation of a-axis grains compared with c-axis grains [5], which leads to films with a generally lower critical transition temperature and poorer crystallinity [6]. While (110) NdGaO 3 substrates [7] have been successfully employed to grow a-axis films, the most reproducible results have been obtained by using a buffer layer technique.…”

Section: Introductionmentioning

confidence: 93%

Study of in-plane electrical transport anisotropy of a -axis oriented YBa2Cu3O7−δ nanodevices

et al. 2017

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In the present work, we report the growth of fully untwinned high-quality a-axis-oriented YBa 2 Cu 3 O 7−δ films on (100) SrLaGaO 4 substrates by using PrBa 2 Cu 3 O 7−δ as a buffer layer. We also fabricated nanowires at different angles γ with respect to the [0,1,0] direction of the substrate and studied the in-plane anisotropy of the critical current density, which we explained by considering the anisotropy in the coherence length ξ and London penetration depth λ L . Finally, half-integer Shapiro-like steps measured in slightly underdoped c-axis oriented (γ = 90• ) nanowires point towards a different transport regime, which could shed light on intriguing issues of high-critical-temperature superconductors.

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“…It was reported that the values of J~ in thin films of Y123 are quite sensitive to the misorientation between the adjacent grains and decrease drastically if the misorientation angle exceeds 10 ~ [12][13][14]. However, it was demonstrated recently that in polycrystaUine thin films (with a- (-b), and e-axis oriented grains) [15,16] and bulk bicrystals [17,18] of Y123, some large-angle (90~ GBs transport high currents. Thus the properties of the grain boundaries might be affected by both the atomic structure and chemical composition.…”

Section: Introductionmentioning

confidence: 99%

Interface and grain boundary structures in YBa2Cu3O7-x and YBa2Cu4O8 materials

et al. 1994

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Y2BaCuOsYBa2CuaOT-~ (Y211/Y123) interfaces in melt-processed YBa2Cu3OT-~ were studied by high-resolution transmission electron microscopy and energy dispersive X-ray spectroscopy. Yttrium enrichment and barium depletion were observed locally at the Y211/Y123 interfaces where Y123 (001) facets were present. This effect may be interpreted as the result of lattice substitution of Ba by Y near these interfaces. Cation nonstoichiometry was found near Y211/Y123 interfaces where liquid phases (Cu-Ba-O) were present. This chemical disorder introduces numerous point defects in the Y123, and these defects may act as additional pinning sites alongwith stacking faults. A comparison of grain boundary (GB) chemical composition in polycrystalline YBa2Cu307-~ and YBa2CuaOs(Y124), studied using nanoprobe parallel-detection electron energy-loss spectroscopy (EELS), is presented. The studies of Y124 show that stoichiometric grain boundaries can also form weak links between superconducting grains. It is suggested that weak-link behavior is determined largely by misorientation at grain boundaries.

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Application of a near coincidence site lattice theory to the orientations of YBa2Cu3O7−x grains on (001) MgO substrates

Cited by 150 publications

References 14 publications

Grain boundary chemistry and grain boundary dislocations in bulk YBa2Cu3O7-?

Grain boundary chemistry and grain boundary dislocations in bulk YBa2Cu3O7-?

Study of in-plane electrical transport anisotropy of a -axis oriented YBa2Cu3O7−δ nanodevices

Interface and grain boundary structures in YBa2Cu3O7-x and YBa2Cu4O8 materials

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